JP2006208762A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a brush fixed in contact with an image carrier, wherein the brush can easily be cleaned, resulting in satisfactory image formation. <P>SOLUTION: The image forming apparatus includes the brush 5 fixed in contact with an intermediate transfer belt 4 (an example of the image carrier). The image forming apparatus includes a brush cleaning member 54 which is movable in contact with the the brush 5 in the direction across the direction of the movement of the surface of the belt 4. The brush 5 is disposed on the upstream side of a rotary brush 501 that cleans and collects toner on the surface of the belt 4. The brush 5 serves as a charging member that pre-charges toner on the belt 4 prior to the collection of toner by the rotary brush. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is in contact with an image carrier such as an electrophotographic copying machine, a laser printer, a facsimile machine, or a combination machine combining two or more of these, which forms a monochrome image or a color image. The present invention relates to an image forming apparatus having a brush fixedly arranged.

  In an image forming apparatus having an image carrier, for example, (1) an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductor, and the latent image is developed into a toner image. (2) forming an electrostatic latent image on the electrostatic latent image carrier, developing the latent image into a toner image, and There are various types such as a color image forming apparatus that primarily transfers an image to an intermediate transfer member (a kind of image carrier) and secondarily transfers a toner image on the intermediate transfer member to a recording medium.

  In an image forming apparatus having such an image carrier, the surface of the electrostatic latent image carrier is uniformly set to a predetermined potential prior to forming an electrostatic latent image by image exposure or the like on the electrostatic latent image carrier. A charging brush may be employed for charging.

In addition, a rotary brush or a fixed brush may be disposed in contact with the image carrier for the purpose of cleaning toner or the like on the image carrier (such as an electrostatic latent image carrier or an intermediate transfer member).
For example, Japanese Patent Laid-Open No. 5-53489 discloses a rotating brush that is driven to rotate in contact with a photosensitive drum.

  Further, the image forming apparatus having the image carrier includes a member that faces the surface of the image carrier and cleans the toner on the image carrier, or collects the toner and the like together with the cleaning. An image carrier cleaning device; and a precharge brush disposed in contact with the surface of the image carrier upstream of the cleaning device in the surface movement direction of the image carrier, and the image carrier is supported by the precharge brush. There is also an image forming apparatus that pre-charges toner on the body to a predetermined charging polarity and uses the cleaning device to clean the pre-charged toner or the like or collect the toner that also serves as a cleaning.

  In any case, the brush that is fixed in contact with the image carrier has toner, toner external additives (toner fluidizing agent, etc.) that existed on the image carrier, and recording medium powder (transfer paper). Paper dust), recording medium filler (talc or the like in the case of transfer paper) and the like are gradually accumulated and accumulated. When toner or the like accumulates in the brush in this way, if the brush is a charging brush, its charging ability is reduced, and if it is a cleaning brush, its cleaning ability is reduced. The pre-charging ability is lowered, and as a result, an image defect occurs.

  The precharged brush will be described as an example. The recording medium powder in the longitudinal direction of the brush (in the direction crossing the surface movement direction of the image carrier with which the brush is in contact) corresponds to the recording medium supply roller. (Paper powder in the case of transfer paper), recording medium filler (talc in the case of transfer paper, etc.) and the like are likely to accumulate, and the pre-charging function of that portion tends to be reduced. Because of such a lowered pre-charging function, cleaning of the toner on the image carrier or collection of the toner that also serves as cleaning becomes insufficient, leading to the occurrence of image defects.

  In this regard, the above-mentioned Japanese Patent Laid-Open No. 5-53489 discloses that a flicker bar is arranged on a cleaning rotary brush which is arranged in contact with a photosensitive member and is driven to rotate, and a protrusion on the bar is bitten into the brush. It discloses that the rotary brush is cleaned by reciprocating the bar.

Japanese Patent Laid-Open No. 5-53489

  However, the electrostatic latent image carrier charging brush, the pre-charging brush arranged in contact with the surface of the image carrier, and the brush fixedly arranged in contact with the image carrier are accumulated in these. There is no means for easily removing toner or the like.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides an image forming apparatus having a brush fixedly disposed in contact with an image carrier, the image forming apparatus capable of easily cleaning the brush and thus forming a good image. Is an issue.

  In order to solve the above problems, the present invention is an image forming apparatus having a brush fixedly arranged in contact with the surface of an image carrier, and the surface movement direction of the image carrier along a brush holding member that holds the brush An image forming apparatus having a brush cleaning member movable in contact with the brush in a direction crossing the brush.

  In the image forming apparatus according to the present invention, toner (for example, toner charged to a polarity opposite to the normal toner charging polarity) and toner external additive (toner fluidization) are placed on a brush fixedly disposed in contact with the image carrier. Agent), recording medium powder (paper powder in the case of transfer paper), recording medium filler (talc in the case of transfer paper, etc.) By moving the cleaning member along the brush holding member and moving the brush cleaning member in contact with the brush, the brush can be easily detached from the brush.

  Furthermore, by moving the brush cleaning member along the brush holding member and thereby moving it in contact with the brush, the brush fibers constituting the brush can be rubbed with the brush cleaning member. The brush fibers can be bent sequentially and restored to the original brush fiber posture by the elasticity of the brush fibers as they pass through the brush cleaning member. In addition, the toner or the like to be collected can be removed from the brush, and the brush can be easily cleaned. As a result, a good image can be formed accordingly.

  When cleaning the brush with the brush cleaning member, the brush cleaning member may be reciprocated one or more times along the brush holding member to clean the brush multiple times, or the brush cleaning member may be moved along the brush holding member. The brush may be cleaned only once by moving in any direction, and in any case, the brush cleaning member may be moved in accordance with the contamination of the brush.

  The brush cleaning member may be moved manually, or a driving device for the brush cleaning member may be provided and moved by the driving device. Such a driving device may be formed using one or more of a gear mechanism such as a rack and pinion, a wire slider mechanism, a cam mechanism, and the like.

  In the image forming apparatus according to the present invention, the image carrier on which the brush to be cleaned by the brush cleaning member is contact-fixed is any of an electrostatic latent image carrier such as a photosensitive member, an intermediate transfer member, and the like. The image carrier may be one or more selected from image carriers that are fixedly placed in contact with a brush for a predetermined purpose such as charging.

  Regarding the positional relationship of the brush that can be cleaned by the brush cleaning member with other members or devices in the image forming apparatus and the purpose or function of the brush, the following cases can be exemplified.

(1) A recovery member facing the surface of the image carrier (for example, rotating in contact with the surface of the image carrier) for recovering toner on the image carrier on which a brush that can be cleaned by the brush cleaning member is fixed. A driven toner recovery rotating member), the contact-fixed brush is positioned on the upstream side of the recovery member in the moving direction of the image carrier surface to A pre-charging brush for pre-charging the toner before the toner is collected by the collecting member.

In this case, the image forming apparatus can include a bias applying device that applies a pre-charging bias to the pre-charging brush.
In addition to the toner, the collecting member may collect recording medium powder and the like.

(2) In the case where an image carrier cleaning device in which a brush that can be cleaned by the brush cleaning member is arranged in contact and fixed is provided, the brush in contact and arrangement is moved in the moving direction of the surface of the image carrier. Located upstream of the cleaning device.

In this case, the contact-fixed brush may have a function required for it. For example, prior to cleaning the image carrier with the cleaning device, the toner or toner on the image carrier is precharged so that the toner or toner on the image carrier can be smoothly cleaned with a cleaning device. It can be used as a pre-charging brush.
When used as a pre-charging brush, a bias applying device that applies a pre-charging bias to the pre-charging brush can be included in the image forming apparatus as in the case of (1).

  Various types of cleaning devices may be employed as the cleaning device. For example, a blade type cleaner or a cleaning rotating member that rotates in contact with the surface of the image carrier may be used. Furthermore, a rotating brush cleaner that employs a rotating brush as the cleaning rotating member may be used. When a cleaning rotating member is employed, it may function as the toner collecting member described in (1) above.

In any case, the image forming apparatus according to the present invention may be any one of an electrophotographic copying machine, a laser printer, a facsimile machine, a combination machine combining two or more of these, which forms a monochrome image or a color image.
In addition, either an intermediate transfer member or a non-transfer member may be used.

  As an example of an image forming apparatus according to the present invention, an electrostatic latent image formed on an electrostatic latent image carrier is developed into a toner image, the toner image is primarily transferred to an intermediate transfer member, and the intermediate transfer An image forming apparatus that secondarily transfers the toner image primarily transferred onto the body to another member (such as a recording medium) can be exemplified. Furthermore, in this image forming apparatus, the image carrier that is fixedly placed in contact with the brush can be exemplified as the intermediate transfer member.

  As an image forming apparatus that employs an intermediate transfer member, a plurality of image forming units are sequentially arranged along the intermediate transfer member, and each image forming unit receives a toner image of a color assigned to the image forming unit. An electrostatic latent image bearing member such as a photosensitive member to be formed on the surface, and a primary transfer member that primarily transfers a toner image on the electrostatic latent image bearing member to the intermediate transfer member. A so-called tandem type image in which a toner image formed by one or more image forming units among the image forming units and primarily transferred onto the intermediate transfer member is secondarily transferred to a recording medium by a secondary transfer member. A forming apparatus can be illustrated.

  In addition, a plurality of image forming units face an electrostatic latent image carrier such as a photoconductor, and each image forming unit places a toner image of a color assigned to the image forming unit on the electrostatic latent image carrier. A toner image that can be developed and formed on the electrostatic latent image carrier by each image forming unit is primarily transferred to an intermediate transfer member sequentially by a primary transfer member, and is primarily transferred onto the intermediate transfer member. A so-called four-cycle type image forming apparatus that secondarily transfers a toner image onto a recording medium by a secondary transfer member can also be exemplified.

  As described above, according to the present invention, an image forming apparatus having a brush fixedly arranged in contact with an image carrier, the image forming apparatus capable of easily cleaning the brush and thus forming a good image accordingly. An apparatus can be provided.

Embodiments of the present invention will be described below.
FIG. 1 shows a schematic configuration of an example A of an image forming apparatus according to the present invention, and FIG. 2 is an enlarged view showing a configuration of a toner cleaning device (an example of a cleaning device) 50 in the image forming apparatus A. FIG. 3 is a block diagram schematically showing a control circuit in the image forming apparatus A.

An image forming apparatus A in FIG. 1 is an electrophotographic image forming apparatus, which is a tandem type full color image forming apparatus.
This image forming apparatus includes an intermediate transfer body 4 that is wound around rollers (pulleys) 31, 32, and 33 and is driven to rotate counterclockwise in the figure (arrow direction in the figure). Here, the intermediate transfer member 4 is an intermediate transfer belt 4 in the form of an endless belt. A toner cleaning device 50 that cleans secondary transfer residual toner and the like on the intermediate transfer belt 4 faces the lower left roller 32 in the figure, and a secondary transfer member 6 faces the roller 31 on the right side in the figure. The secondary transfer member 6 is here a secondary transfer roller 6 in the form of a roller. A fixing device 7 is installed above the secondary transfer roller 6.

Between the rollers 32 and 31, the yellow image forming unit Y, the magenta image forming unit M, the cyan image forming unit C, and the black image forming unit K are arranged in this order along the intermediate transfer belt 4 from the rollers 32 to 31. Is arranged in.
Each image forming unit includes a drum-type photoconductor 11 as an electrostatic latent image carrier, and a charging device 12, an image exposure device 13, a developing device 14, a primary transfer member 2, and a photosensitive member are provided around the photoconductor. Cleaners 15 for removing primary transfer residual toner and the like on the body are arranged in this order. Here, the primary transfer member 2 is a primary transfer roller 2 in the form of a roller, and faces the photoreceptor 1 with the intermediate transfer belt 4 in between.

The developing device 14 in each image forming unit employs a negatively chargeable toner, and reversely develops the electrostatic latent image formed on the photoconductor 11.
In each image forming unit, the photoconductor 11, the charging device 12, the image exposure device 13, the developing device 14, and the cleaner 15 are attached and held in one case 1, and the photoconductor 11 faces the transfer belt 4 from within the case 1. In contact with the belt 4.

  Below the four image forming portions Y, M, C, and K, a supply cassette 8 for a recording medium (recording paper S in this example) is provided, and the recording paper S accommodated therein is fed to the paper feed roller 81. Are pulled out and supplied one by one.

  A predetermined high voltage for charging the photosensitive member is applied to the charging device 12 of each image forming unit from a power source (not shown) at a predetermined timing under the instruction of the control unit Cont (see FIG. 3). A predetermined developing bias from a developing bias power supply (not shown) is applied to the developing roller 141 of the developing device 14 of each image forming unit at a predetermined timing under the instruction of the control unit Cont.

  A primary transfer voltage is applied to the primary transfer roller 2 from an unillustrated primary transfer power source for the image forming unit, and the toner image on the photosensitive drum 11 is intermediately transferred to the primary transfer roller 2 under the instruction of the control unit Cont. It is applied at the timing of primary transfer to the belt 4.

  A secondary transfer voltage is applied to the secondary transfer roller 6 at the timing of secondary transfer of the toner image on the intermediate transfer belt 4 from the power supply (not shown) to the recording paper S under the instruction of the control unit Cont. The

  In each image forming unit, the photosensitive member 11, the primary transfer roller 2, the rotation member such as the rotation member in the developing device 14, the operation of the image exposure device 13, and the secondary transfer roller 6 and the intermediate transfer belt 4 are wound around. Among the rollers, the operation of the driving roller 31, the fixing device 7, the paper feed roller 81, the toner cleaning device 50, and the like are also operated at a predetermined timing under the instruction of the control unit CONT. The toner cleaning device 50 will be described in detail later.

According to this image forming apparatus A, image formation is performed as follows.
First, an image is formed in at least one of the image forming portions Y, M, C, and K according to an image to be finally formed.
Taking a case where a full color image is formed using all of the image forming portions Y, M, C and K as an example, first, a yellow toner image is formed in the yellow image forming portion Y, and this is formed on the intermediate transfer belt 4 as a primary. Transcribed.

  That is, in the yellow image forming portion Y, the photoconductor 11 is rotated in the clockwise direction in the drawing, and the surface of the photoconductor 11 is uniformly charged to a predetermined potential by the charging device 12, and the image exposure device 13 is placed in the charged area. Then, image exposure for yellow image is performed, and an electrostatic latent image for yellow is formed on the photoreceptor 11. The electrostatic latent image is developed by a developing roller 141 to which a developing bias of a developing device 14 having yellow toner is applied to become a visible yellow toner image, and the toner image is a primary transfer roller to which a primary transfer voltage is applied. 2 is transferred onto the intermediate transfer belt 4.

  Similarly, a magenta toner image is formed in the magenta image forming unit M and transferred to the intermediate transfer belt 4, and a cyan toner image is formed and transferred to the intermediate transfer belt 4 in the cyan image forming unit C. A black toner image is formed at K and transferred to the intermediate transfer belt 4.

The yellow, magenta, cyan, and black toner images are formed at the timing when they are transferred onto the intermediate transfer belt 4 in an overlapping manner.
Thus, the multiple toner image formed on the intermediate transfer belt 4 moves toward the secondary transfer roller 6 by the rotation of the intermediate transfer belt 4.

  On the other hand, the recording paper S is pulled out from the recording paper supply cassette 8 by the paper supply roller 81, and then, by the timing roller pair 91 and 92, the intermediate transfer belt 4 and the secondary transfer are synchronized with the multiple toner images on the belt 4. The multiple toner images are secondarily transferred onto the recording paper S by the secondary transfer roller 6 supplied between the rollers 6 and applied with a secondary transfer voltage. Thereafter, the recording paper S is passed through the fixing device 7 where the multiple toner images are fixed on the recording paper S under heat and pressure, and a predetermined color image is formed on the recording paper S. Thereafter, the recording paper S is discharged onto the paper discharge tray T by the paper discharge roller pair R.

In each image forming unit, the primary transfer residual toner and the like remaining on the photoconductor 11 after the primary transfer is cleaned and removed by the cleaner 15. Further, after the secondary transfer, the secondary transfer residual toner remaining on the intermediate transfer belt 4 is cleaned and collected by the toner cleaning device 50.
Most of the toner remaining on or adhering to the photoreceptor 11 after the primary transfer is the primary transfer residual toner, but in the belt 4 portion after the secondary transfer, the secondary transfer residual toner In addition, there are paper dust derived from the recording paper S, a filler (talc, etc.) of the recording paper, and the developing device 14 in the image forming unit adopts a two-component developer. The included carrier may be attached.

Next, the toner cleaning device 50 will be further described.
If the toner cleaning device 50 is provided between the secondary transfer member 6 and the primary transfer member 2 of the most upstream image forming portion (Y in this example) in the surface movement direction of the intermediate transfer belt 4, In the image forming apparatus A, as shown in FIG. 2, the image forming apparatus A is provided for the transfer belt portion positioned on the roller 32 around which the intermediate transfer belt 4 is wound. Thereby, the secondary transfer residual toner or the like on the belt 4 is cleaned and collected.
The toner cleaning device 50 includes a toner rotation collecting member 501 that also serves as a belt cleaning disposed in contact with the transfer belt 4. The collection rotating member 501 is a rotating brush 501 in this example.

  The toner cleaning device 50 is further scraped off by a fixed position blade 503 and a blade 503 that mechanically scrapes the collection roller 502 disposed in contact with the rotating brush 501 and the secondary transfer residual toner on the collection roller 502. The toner that may fly up in the form of dust when the toner is scraped off by the conveying screw 504 and the blade 503 for carrying out the toner is prevented from being reattached to the belt 4 in the air current generated by the rotation of the rotating brush 501. In order to do so, a seal member 505 is disposed in contact with the collection roller 502.

  These components are provided in the case 500 in a state of being incorporated in the case 500. However, a part of the rotating brush 501 is exposed from the case and is in contact with the belt 4.

  The image forming apparatus A also includes a pre-charging member 5 positioned on the upstream side of the rotating brush 501 in the moving direction of the surface of the belt 4 (the image carrying surface on the side on which the toner image is primarily transferred from the photoreceptor 11). Furthermore, it also has a pre-charging member cleaning device 5A having a compact structure that is simple in structure and inexpensive.

  The pre-charging member 5 may be any material that can inject electric charges upon contact with the toner or the like on the belt 4, and may be a conductive resin sheet or a metal sheet. Here, a brush is employed as one that can contact under low pressure.

  More specifically, as shown in FIGS. 1 and 2, the pre-charging member (pre-charging brush) 5 is composed of a conductive brush (brush body) 51 and a conductive plate-like member 52 to which this is attached. . In this example, the plate-like member 52 is held by an electrically insulating brush holding member 53, and the holding member 53 is supported by a case 500 of the toner cleaning device 50. Thus, the entire precharging member 5 is supported by the case 500, and the brush 51 is fixedly disposed in contact with the belt 4. Since the pre-charging member 5 is a fixed arrangement type, it can be manufactured at a lower cost than a movable member and contributes to space saving of parts.

  As shown in FIGS. 1 and 2, the cleaning device 5 </ b> A for the pre-charging member 5 includes a brush cleaning member 54 having a circular cross section and a slider 55 that cantilever-supports the cleaning member 54. The slider 55 is placed on the upper surface of the brush holding member 53 with the end of the cleaning member 54 that cantilever-supported engages the end 531 of the brush holding member 53 slidably. The opposite end of 55 is slidably engaged with a guide member 56 provided on the upper surface of the brush holding member 53.

Thus, the slider 55 can reciprocate along the brush holding member 53 in a direction substantially perpendicular to the surface movement direction of the transfer belt 4, and the brush cleaning member 54 contacts the brush 51 by the reciprocation of the slider 55. However, it can reciprocate in the same direction.
If the rod-shaped cleaning member 54 is too low in rigidity, not only the cleaning performance of the brush 51 is deteriorated but also there is a risk that the intermediate transfer belt 4 may be bent down and damaged. It shall have.

  Each rotating member in the toner cleaning device 50 is driven to rotate together with an instruction from the control unit Cont. At that time, the rotating brush 501 is able to sufficiently scrape and collect the toner and the like on the belt 4. It is rotationally driven around the counter direction (counterclockwise in FIG. 1) so that the brush fibers move against the moving direction of the surface. The collection roller 502 is driven to rotate clockwise in FIG.

The rotating brush 501, the collection roller 502, and the precharging member 5 are all conductive in this example.
The rotating brush 501 is made by weaving conductive brush fibers (raw yarn) into a conductive base fabric that is entirely conductive or (and) a conductive base fabric coated with a conductive agent on the back, and the conductive brush fibers. A base fabric is wound around a core and bonded so as to be conductive between the two (for example, bonded using a conductive adhesive). The core metal may be formed of, for example, a bar made of a conductive metal, a pipe, or the like.

Examples of the material of the conductive brush fiber include polyamide (nylon and the like) in which conductive carbon is dispersed, polyester, acrylic, rayon and the like.
As for the thickness and resistance of the brush fiber, the thickness can be exemplified as 1 decitex to 10 decitex as the yarn diameter, and the resistance can be exemplified as 10 ³ Ω / cm to 10 ¹⁵ Ω / cm as the yarn resistance. Examples of the brush fiber density in the base fabric include 50 kF / inch ^{2 to} 300 kF / inch ² (k is 10 ³ , and F is the number of fibers [lines]).

  In this example, a rotating brush 501 using such brush fibers is used, and the relationship between the surface moving speed of the belt 4 and the rotating brush peripheral speed is expressed by a peripheral speed ratio θ (rotating brush peripheral speed / belt surface moving speed). The peripheral speed ratio θ and the amount of biting were set to about 1 to 5 and the amount of biting of the belt 4 into the brush 51 was about 0.5 mm to 2 mm.

The brush 51 in the pre-charging member 5 is also the same brush fiber as that used for forming the rotating brush 501 (however, the resistance may be lower than that of the rotating brush 501 for smooth charge injection) and the base fabric. And the brush fiber is formed by weaving the base fabric at a fiber density of about 50 kF / inch ^{2 to} 300 kF / inch ^2. Thus, the pre-charging member 5 is bonded to be conductive (for example, bonded using a conductive adhesive). The amount of biting of the belt 4 into the brush 51 may be set to about 0.5 mm to 2 mm.

  As shown in FIG. 2, the toner cleaning device 50 and the precharging member 5 are provided with a power source PW1 for forming a cleaning electric field for cleaning and collecting secondary transfer residual toner and the like on the belt 4. The power source PW1 is connected to the core of the collecting roller 502 on the one hand and to the plate-like member 52 of the pre-charging member 5 via the open / close switch SW1 on the other hand.

  When forming the cleaning electric field, the switch SW1 is closed under the instruction of the control unit Cont. At the time of forming the cleaning electric field, the rotary brush 501 is set to a polarity [positive (+)] side opposite to the normal charging polarity [negative (−)] of the toner on the belt 4 via the collection roller 502. A current flows through the intermediate transfer belt 4 to the conductive pre-charging member 5 on the upstream side, and the pre-charging member 5 is set to the same polarity (−) side as the normal charging polarity (−) of the toner on the belt 4.

  The electric field formed by the power source PW1 may be either a constant voltage or a constant current. In the case of voltage, for example, it may be set to several kV or less, and in the case of current, for example, set to 100 μA or less.

According to the toner cleaning device 50 and the pre-charging member 5, the toner on the belt 4 can be cleaned and collected during image formation as follows.
That is, when the switch SW1 is closed under the instruction of the control unit Cont, a part of the toner on the belt 4 or further paper dust or the like is made negative by charge injection from the precharge member 5, and the precharge is performed. The charged toner or the like repels the polarity (−) of the precharging member 5, moves to the belt 4 without accumulating on the precharging member 5, and is conveyed to the rotating brush 501 by the rotation of the belt 4. The toner is scraped and collected from the belt 4 under a cleaning electric field by a rotating brush 501 set to the opposite polarity (+) side to the toner of normal charging polarity.

  Thus, the toner or the like collected on the rotary brush 501 after the transfer belt 4 is cleaned is further collected on a collection roller 502 that rotates in contact with the brush, and the toner on the collection roller 502 is scraped off by a blade 503. The conveying screw 504 is carried out to a container or the like (not shown).

As described above, while collecting the toner on the belt 4 by the cleaning electric field, the toner, the toner external additive, the paper powder, and the recording that are difficult to be charged with the normal charging polarity (−) existing on the traveling belt 4 are recorded. Paper filler or the like gradually accumulates on the brush 51 of the pre-charging member 5.
However, in this image forming apparatus A, in the cleaning device 5A for the pre-charging member 5, the slider 55 is moved in one direction along the brush holding member 53, or is reciprocated once or twice or more to clean the brush cleaning member. The brush 51 can be easily cleaned by moving the brush 54 in contact with the brush 51.

  That is, by moving the brush cleaning member 54 in contact with the brush 51 in this way, the brush fibers constituting the brush can be rubbed with the brush cleaning member 54, and the brush fibers are further bent sequentially. As the brush cleaning member 54 passes, the original brush fiber posture can be restored by the elasticity of the brush fibers, and the brush 51 is or will be accumulated by the brush fiber rubbing operation and the brush fiber bending and restoring operation. The toner or the like to be removed can be removed from the brush for easy brush cleaning.

The toner or the like released from the brush 51 onto the belt 4 by the brush cleaning is directed to the rotating brush 501 by the rotation of the belt 4 and is cleaned and collected by the rotating brush 501 under a cleaning electric field.
Thus, the pre-charging function of the pre-charging member 5 can be maintained normally over a long period of time, and a good image can be formed over that long period.

  The pre-charging brush 51 is preferably cleaned by the brush cleaning member 54 at the time of non-image formation so as not to affect the image formation. Here, at the time of non-image formation, a normal image is formed. Before the start of image formation (during pre-rotation), during that time (between images when continuously forming a plurality of images), after the end of image formation (during post-rotation), etc.

The driving of the brush cleaning member 54 by the slider 55 may be performed manually, or a driving device for the slider 55 and the cleaning member 54 may be provided and moved by the driving device under the instruction of the control unit Cont. Such a driving device may be formed using one or more of a gear mechanism such as a rack and pinion, a wire slider mechanism, a cam mechanism, and the like.
Examples of the cleaning timing when performing manual cleaning include before the start of image formation (during pre-rotation) and after completion of image formation (during post-rotation). The brush 51 may be cleaned while the intermediate transfer belt 4 is stopped. In this case, the toner or the like discharged from the brush 51 onto the belt 4 is collected by the rotating brush 501 by the next rotation of the belt 4 accompanied with the formation of the cleaning electric field.
These points are the same in other examples of the pre-charging member cleaning device described later.

  FIG. 4 shows the width of the belt 4 in the direction perpendicular to the surface movement direction of the intermediate transfer belt 4, the width of the image area on the belt 4, the width of the paper feed roller 81, and the width of the brush (brush body) 51 in the precharging member 5. And an example of the movement range of the brush cleaning member 54 is shown.

  As shown in FIG. 4, the cleaning of the brush 51 by the cleaning member 54 is preferably performed over the entire brush 51, but the cleaning device is required to be downsized for reasons such as an increase in the cleaning device. In this case, at least the portion of the brush 51 corresponding to the paper feed roller 81 may be cleaned. This is because paper dust or the like derived from the recording paper S is particularly likely to collect in the brush 51 portion corresponding to the paper feed roller 81.

Further, when the brush 51 is not cleaned by the cleaning member 54, it is desirable that the member 54 is retracted outside the image area and further outside the brush 51. However, because of the relationship of the movement range of the member 54 due to the balance with the paper feed roller 81, the member 54 may not be stored in the retracted position but may be placed at a position corresponding to the paper feed roller 81 in the center of the image area. . However, in that case, it is desirable to reduce the thickness of the cleaning member 54 so that the contact uniformity of the brush fibers to the belt 4 is not impaired.
These points are the same in other examples of the pre-charging member cleaning device to be described later.

  FIG. 5 shows another example of the pre-charging member cleaning device. In the cleaning device 5B shown in FIG. 5, the plate-like member 52 that supports the brush 51 of the pre-charging member 5 is held by a brush holding member 53 ′, and the holding member 53 ′ is erected on the upper surface (back surface) thereof. In addition, the toner cleaning device case 500 is attached via a member 532 that supports the member 531. Thus, the entire precharging member 5 is supported by the case 500, and the brush 51 is arranged in contact with and fixed to the belt 4.

  Sliders 571 are slidably engaged with both ends of the brush holding member 53 ′, both sliders 571 are connected by members 570, and a brush cleaning member 54 is stretched between these sliders 571. is there. A long through hole 570a is formed in the connecting member 570 in a direction crossing the surface moving direction of the belt 4, and a member 531 standing on the back surface of the brush holding member 53 'is loosely fitted in the hole 570a.

According to this cleaning device 5B, the brush 51 can be cleaned by moving the slider 571 along the brush holding member 53 ′.
Since the cleaning member 54 is stably stretched and supported between the pair of sliders 571 as compared with the case of the cantilever support by the slider 55 shown in FIG. 1, the brush cleaning can be performed more reliably. Further, there is an advantage that options such as the material and form of the member 54 are expanded. Furthermore, there is little risk of damaging the transfer belt 4.

  FIG. 6 shows still another example of the pre-charging member cleaning device. The cleaning device 5C shown in FIG. 6 employs a material made of a flexible material as the brush cleaning member 54 provided between the sliders 571 in the cleaning device 5B of FIG. Other points are the same as the cleaning device 5B.

  In the cleaning device 5C of FIG. 6, the brush cleaning member rigidity as required by the devices 5A and 5B is not necessary. The brush cleaning member 54 in the device 5C can be a flexible thin fiber, a wire, a metal wire, or the like that does not damage the belt as much as practically problematic even if it contacts the belt 4. For this reason, the freedom degree of design of the cleaning apparatus 5C is so much. Assuming that the brush cleaning member 54 comes into contact with the intermediate transfer belt 4, it is desirable to avoid a material such as rubber having a friction coefficient μ that is too large.

FIG. 7 shows still another example 5D of the pre-charging member cleaning device. FIG. 7A is a side view of the cleaning device 5D, and FIG. 7B is a plan view of the cleaning device 5D.
In the cleaning device 5D shown in FIG. 7, the plate-like member 52 that supports the brush 51 of the pre-charging member 5 is held by the brush holding member 53 ″, and the holding member 53 ″ is attached to the toner cleaning device case 500. Thus, the entire precharging member 5 is supported by the case 500, and the brush 51 is arranged in contact with the belt 4.

  An arm 58 that cantilever-supports the brush cleaning member 54 is supported on the upper surface of the brush holding member 53 "by a bearing 581 so as to be reciprocally rotatable. The arm 58 is reciprocally rotated along the brush holding member 53". Thus, the brush cleaning member 54 can rotate along the brush holding member 53 ″ while contacting the brush 51 to clean the brush 51.

  The cleaning of the brush 51 by the cleaning member 54 is preferably performed over the entire brush 51. However, when the cleaning device 5D needs to be downsized due to an increase in the size of the cleaning device 5D, the cleaning device 5A. Similarly to the above description, at least the portion of the brush 51 corresponding to the paper feed roller 81 may be cleaned. In any case, when the cleaning member 54 is not used, the member 54 can be stored outside the brush 51.

Regardless of which pre-charging member cleaning device described above is employed, when the brush 51 of the pre-charging member 5 is cleaned, an alternating electric field is applied to the pre-charging member 5 (brush 51) and the toner collected on the brush 51 is collected. The brush 51 may make it easier to discharge paper dust or the like.
FIG. 8 shows a part of an image forming apparatus to which such an alternating electric field can be applied.
In the example shown in FIG. 8 as well, the power source PW1 and the open / close switch SW1 for forming the cleaning electric field for cleaning the belt 4 employed in the image forming apparatus A of FIG. An AC power supply PW2 and a changeover switch SW2 are used for application.

The power source PW1 is connected to the core metal of the collecting roller 502 on the one hand and to the pre-charging member 5 via the switches SW1 and SW2 on the other hand. The power source PW2 is connected to the precharging member 5 via the switch SW2.
The cleaning electric field is formed by the power source PW1 by closing the switch SW1 and connecting the precharge member 5 to the power source PW1 by the switch SW2.
The application of an alternating electric field to the precharging member 5 at the time of cleaning the precharging brush is performed by a connection operation of the precharging member 5 to the power source PW2 by the switch SW2.

  INDUSTRIAL APPLICABILITY The present invention can be used in an image forming apparatus to clean an image carrier and form a good image for a long time.

1 is a diagram schematically illustrating a configuration of an example of an image forming apparatus according to the present invention. FIG. 2 is an enlarged view illustrating a toner cleaning device, a precharge member, and a precharge member cleaning device in the image forming apparatus of FIG. 1. FIG. 2 is a block diagram illustrating an outline of a control circuit of the image forming apparatus in FIG. 1. FIG. 6 is a diagram illustrating a relationship among an intermediate transfer belt width, an image area width, a paper feed roller width, a brush width of a pre-charging member, and a moving range example of a brush cleaning member. It is a figure which shows the other example of the pre-charging member cleaning apparatus. It is a figure which shows the further another example of the pre-charge member cleaning apparatus. It is a figure which shows the further another example of a pre-charge member cleaning apparatus, FIG. 7 (A) has shown the side surface, FIG.7 (B) has shown the plane. It is a figure which shows a part in the other example of the image forming apparatus concerning this invention.

Explanation of symbols

A Image forming apparatus Y Yellow image forming part M Magenta image forming part C Cyan image forming part K Black image forming part 1 Image forming part case 11 Photoconductor 12 Charging device 13 Image exposing device 14 Developing device 141 Developing roller 15 Cleaner 2 Primary Transfer roller 31, 32, 33 Belt winding roller (pulley)
4 Intermediate transfer belt 50 Toner cleaning device 500 Toner cleaning device case 501 Rotating brush 502 Recovery roller 503 Scraping blade 504 Conveying screw 505 Seal member 5 Pre-charging member 51 Brush (brush body)
52 Plate-like members 5A, 5B, 5C, 5D with brush 51 attached Pre-charging member cleaning device 53 Brush holding member 531 End 54 of holding member 53 Brush cleaning member 55 Slider 56 Guide member 53 ′ Brush holding members 531 and 532 Member 571 Slider 570 Slider connecting member 570a Through hole 53 "Brush holding member 58 Arm 581 Bearing portion 6 Secondary transfer roller 7 Fixing device 8 Recording paper supply cassette S Recording paper 81 Paper feed rollers 91, 92 Timing roller pair R Ejection Paper roller pair T Paper discharge tray PW1, PW2 Power supply SW1, SW2 Switch Cont Control section

Claims (6)

  An image forming apparatus having a brush fixedly disposed in contact with the surface of an image carrier, and in contact with the brush in a direction crossing the surface movement direction of the image carrier along a brush holding member that holds the brush. An image forming apparatus having a movable brush cleaning member.   A recovery member facing the surface of the image carrier for recovering the toner on the image carrier; and the brush is positioned upstream of the recovery member in the moving direction of the surface of the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is a pre-charging brush for pre-charging the toner on the image carrier prior to recovery by the recovery member.   The image forming apparatus according to claim 2, further comprising a bias applying device that applies a bias to the pre-charging brush.   The image forming apparatus according to claim 1, further comprising a cleaning device for the image carrier, wherein the brush is positioned upstream of the cleaning device in a moving direction of the surface of the image carrier.   The image forming apparatus according to claim 4, wherein the cleaning device is a rotary brush cleaner having a rotary brush that rotates in contact with the surface of the image carrier.   The electrostatic latent image formed on the electrostatic latent image carrier is developed into a toner image, the toner image is primarily transferred to the intermediate transfer member, and the toner image primarily transferred onto the intermediate transfer member is obtained. 6. The image forming apparatus according to claim 1, wherein the image carrier is secondarily transferred to another member, and the image carrier that is fixedly placed in contact with the brush is the intermediate transfer body.