JP2007121568A - Cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently remove powder of a toner containing external additives with relatively low resistance from a surface of a powder carrier. <P>SOLUTION: Disclosed are a cleaning brush (2) which is applied with an electric field for cleaning to electrostatically remove powder sticking on the surface of the powder carrier (B) carrying the powder on the surface, and a cleaning device (CL2) having the cleaning brush (2) of ≥10 logΩcm in volume resistivity of bristles of a brush and ≥0.3 gf/mm in brush tip force. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning device for cleaning the surface of a powder carrier on which powder such as toner or paper powder is carried. The present invention can be suitably used for a cleaning device of an image forming apparatus such as an electrophotographic copying machine, a FAX, a printer, and a multifunction machine in which the toner as the powder is used.

In the electrophotographic image forming apparatus, a toner image carried on the surface of a powder carrier including an intermediate transfer belt and a photoreceptor is electrostatically transferred onto a transfer material (paper, intermediate transfer belt, etc.). In such an image forming system, there is a case where the image is not transferred to the transfer material but remains on the surface of the powder carrier, or the paper powder is reversely transferred from the transfer material. Since powder such as residual toner and paper powder on the surface of the powder carrier causes deterioration of image quality, it is necessary to remove the powder from the surface of the powder carrier.
In order to remove the powder from the surface of the powder carrier, a technique of sliding a cleaning brush (brush roller) on the surface of the powder carrier is conventionally known. In the technique using such a cleaning brush, the technique described in the following documents (1) and (2) is a technique in which the brush tip force for scraping residual toner from the surface of the powder carrier is set within a suitable range. This technique is conventionally known.
(1) Technology described in Patent Document 1 (Japanese Patent Laid-Open No. 8-115031) In Patent Document 1, the tip force of the brush as a force for scraping the residual toner on the photosensitive member is set to 0.05 gf / mm or more. A brush is described.
(2) Technology described in Patent Document 2 (Japanese Patent Application Laid-Open No. 6-236134) Patent Document 2 describes a brush tip force as a force for scraping off residual toner on a photoconductor from 0.3 g / mm to 1.6 g. A cleaning brush set in the range of / mm is described.

In recent years, in order to improve image quality, toner diameters and spheres have been reduced. For this reason, in the techniques described in Patent Documents 1 and 2, when toner having a reduced diameter or a spherical shape is used, residual toner attached to the surface of the photoreceptor may not be sufficiently removed.
Further, by applying a bias to the cleaning brush, the residual toner scraped off from the surface of the photoconductor is electrostatically adsorbed to the cleaning brush, and the adsorbed residual toner is removed from the cleaning brush to thereby remove the surface of the photoconductor. There is a cleaning technique. As such a technique, techniques described in the following documents (3) to (5) are conventionally known.
(3) Technology described in Patent Document 3 (Japanese Patent Application Laid-Open No. 6-130875) Patent Document 3 describes a technique for cleaning the surface of a photoreceptor with a cleaning brush having fibers having a volume resistivity of 10 ² Ωcm to 10 ⁸ Ωcm. Is described.
(4) Technology described in Patent Document 4 (Japanese Patent Application Laid-Open No. 2004-170534) Patent Document 4 describes a residual toner on the surface of a photoreceptor by a brush roller having a brush portion having a volume resistivity of 20 Ωcm or more and 10 ⁸ Ωcm or less. A technique for removing (transfer residual toner) is described.
(5) Technology described in Patent Document 5 (Japanese Patent Laid-Open No. 5-19670) Patent Document 5 describes that the surface of a photoreceptor is cleaned by a cleaning brush having a brush having a volume resistivity of 10 ⁵ Ωcm or more, preferably about 10 logΩcm. The technology to do is described.

JP-A-8-115031 (paragraph numbers “0016” to “0023”) JP-A-6-236134 (paragraph number “0007”) JP-A-6-130875 (paragraph number “0026”) JP 2004-170534 A (paragraph number “0049”) Japanese Patent Laid-Open No. 5-19670 (paragraph numbers “0045” to “0048”)

(Problems of the techniques described in Patent Documents 3 to 5)
Various external additives are added to the toner in order to obtain chargeability, transferability, fluidity, or maintainability thereof. As the external additive, one having a resistance value of about 15 log Ωcm is generally used. For this reason, generally, a cleaning brush having a brush hair volume resistivity of about 10 ⁸ Ωcm has been used.
However, an external additive having a relatively low resistance (about 11 log Ωcm) may be added to the toner as the diameter of the toner becomes smaller or spherical. When such a toner is used, electric charge is easily injected into the toner by the cleaning brush. When electric charge is injected into the toner, a cohesive force is generated between the toners and the cleaning performance is deteriorated. Therefore, in the techniques described in Patent Documents 3 to 5, when using a toner to which an external additive having a relatively low resistance of about 11 log Ωcm is used, the residual toner on the surface of the photoreceptor may not be sufficiently removed. .

As a result of diligent experiments and researches, the present inventors have found that it is sufficient to simply use a cleaning brush having a high volume resistivity of the brush hair when using a toner to which a relatively low resistance external additive is added. It was found that the cleaning ability could not be obtained and the tip force also had a great influence.
In Patent Documents 1 to 5, there is no document that has been sufficiently studied about both the volume resistivity and the tip force of the brush hair, and the toner to which a relatively low resistance external additive is added should be sufficiently removed. There is a problem that can not be.

In view of the above circumstances, the present invention has the following description (O01) as a technical problem.
(O01) To sufficiently remove powder such as toner containing an external additive having a relatively low resistance from the surface of the powder carrier.

Next, the present invention devised to solve the above problems will be described. In order to facilitate correspondence with the constituent elements of the embodiments described later, the constituent elements of the present invention are not described. Add the code enclosed in parentheses.
The reason why the present invention is described in correspondence with the reference numerals of the embodiments described later is to facilitate the understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(First invention)
In order to solve the above problems, the cleaning device (CL2) of the first invention is characterized by comprising the following structural requirements (A01) and (A02).
(A01) Powder carrier (B) carrying powder on the surface,
(A02) A cleaning brush (2) to which a cleaning electric field is applied to electrostatically remove the powder adhering to the surface of the powder carrier (B), and the volume resistivity of the brush hair is 10 logΩcm or more and The cleaning brush (2) having a brush tip force of 0.3 gf / mm or more.
(Operation of the first invention)
In the cleaning device (CL2) according to the first aspect of the present invention having the structural requirements (A01) and (A02), the powder carrier carries powder on its surface.
The cleaning brush (2) is applied with a cleaning electric field for electrostatically removing the powder adhering to the surface of the powder carrier (B). The cleaning brush (2) has a brush bristle volume resistivity of 10 log Ωcm or more and a brush tip force of 0.3 gf / mm or more.
Therefore, the cleaning brush (2) can sufficiently remove the powder adhering to the surface of the powder carrier (B) by combining the high resistance of the bristle and the high tip force.

(Embodiment 1 of the present invention)
The cleaning device (CL2) according to the first embodiment of the present invention is characterized in that, in the first invention, the following configuration requirement (A03) is provided.
(A03) The powder composed of toner.
(Operation of Form 1 of the Present Invention)
In the cleaning device (CL2) according to Embodiment 1 of the present invention including the component (A03), the powder is composed of toner. The cleaning brush (2), which combines high resistance of brush hair and high tip force, can sufficiently remove the toner adhering to the surface of the powder carrier (B).

(Embodiment 2 of the present invention)
The cleaning device (CL2) of Embodiment 2 of the present invention is characterized in that the following configuration requirement (A04) is provided in Embodiment 1 of the present invention.
(A04) The toner containing an external additive having a resistance value of 11 log Ωcm or less.
(Operation of Embodiment 2 of the present invention)
In the cleaning device (CL2) according to the second embodiment of the present invention having the component (A04), the toner contains an external additive having a resistance value of 11 log Ωcm or less. The cleaning brush (2), which combines high resistance of the brush hair and high tip strength, can be used even when the toner containing a relatively low resistance external additive of 11 log Ωcm or less is used. B) The toner adhering to the surface can be sufficiently removed.

(Embodiment 3 of the present invention)
The cleaning device (CL2) according to the third embodiment of the present invention is characterized in that the following constitutional requirements (A05) and (A06) are provided in the first invention or the first or second embodiment of the present invention.
(A05) An electrostatic adsorption member (3) disposed in contact with the cleaning brush (2) and electrostatically adsorbing and removing powder from the cleaning brush (2),
(A06) Applying the suction voltage (V3, V4) to the electrostatic chuck member (3) so that the potential difference between the cleaning brush (2) and the electrostatic chuck member (3) is 600V or more. Suction voltage application device (E3, E4).

(Operation of Form 3 of the Present Invention)
In the cleaning device (CL2) of the third embodiment of the present invention including the components (A05) and (A06), the electrostatic attraction member (3) is disposed in contact with the cleaning brush (2), and the cleaning device The powder is electrostatically adsorbed and removed from the brush (2).
The attracting voltage application device (E3, E4) is attracted to the electrostatic attracting member (3) so that a potential difference between the cleaning brush (2) and the electrostatic attracting member (3) is 600 V or more. Application voltages (V3, V4) are applied.
The powder removed from the surface of the powder carrier (B) by the cleaning brush (2) is temporarily held by the cleaning brush (2), and then rotates with the cleaning brush (2). It moves to a contact part (Q8) with the electrostatic adsorption member (3). In the contact portion (Q8), the powder temporarily held by the cleaning brush (2) is electrostatically moved and attracted to the electrostatic attracting member (3). Therefore, the cleaning brush (2) is cleaned by the electrostatic attraction member (3).

(Embodiment 4)
A cleaning device (CL2) according to a fourth embodiment of the present invention is characterized in that in any one of the first invention or the first to third embodiments of the present invention, the following structural requirements (A07) and (A08) are provided.
(A07) The powder carrier (B) constituted by the intermediate transfer belt (B),
(A08) A scraper (4) that abuts on the electrostatic adsorption member (3) and scrapes the powder adsorbed on the surface of the electrostatic adsorption member (3).
(Operation of Form 4 of the Present Invention)
In the cleaning device (CL2) according to the fourth embodiment of the present invention having the components (A07) and (A08), the powder carrier (B) is constituted by an intermediate transfer belt (B).
The scraper (4) contacts the electrostatic adsorption member (3) and scrapes the powder adsorbed on the surface of the electrostatic adsorption member (3).
The powder adhering to the intermediate transfer belt (B) is electrostatically moved and attracted to the electrostatic attraction member (3) via the cleaning brush (2). The powder adsorbed on the electrostatic adsorption member (3) moves to the contact portion with the scraper (4) as the electrostatic adsorption member (3) rotates. In the contact portion, the powder adsorbed on the electrostatic adsorption member (3) is scraped off by the scraper (4). Therefore, the electrostatic attraction member (3) is cleaned by the scraper (4).

The above-described cleaning device of the present invention has the following effect (E01).
(E01) Powders such as toner and paper powder containing an external additive having a relatively low resistance of 11 log Ωcm or less can be sufficiently removed from the surface of the powder carrier.

Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.

Example 1
FIG. 1 is an overall explanatory view of an image forming apparatus provided with a cleaning device of the present invention.
In FIG. 1, the image forming apparatus U has an image forming apparatus main body U1 and an automatic document feeder U2 placed on a platen glass PG on the upper surface of the image forming apparatus main body U1. The image forming apparatus main body U1 has a UI (user interface) through which a user inputs an operation command signal such as a copy start.
The automatic document feeder U2 conveys a document feed tray TG1 on which a plurality of documents Gi to be copied are stacked and a copy position P on the platen glass PG from the document feed tray TG1. And a document discharge tray TG2 from which the document Gi to be discharged is discharged.

Reflected light from the document Gi conveyed from the document feed tray TG1 to the copy position P or from the document Gi manually placed on the platen glass PG passes through the exposure optical system A and is a CCD (solid-state imaging device). Are converted into electrical signals of R (red), G (green), and B (blue).
The IPS (Image Processing System) converts the RGB electrical signals input from the CCD into Y (yellow), M (magenta), C (cyan), and K (black) image data and temporarily stores them. The image data is output to the laser drive circuit DL as image data for forming a latent image at a predetermined timing.
The laser drive circuit DL outputs a laser drive signal to the ROS (electrostatic latent image forming apparatus) according to the input image data.

The image carrier (photosensitive member, powder carrier) PR constituted by the photosensitive drum rotates in the direction of the arrow Ya, and the surface thereof is uniformly charged by the charging roll CR in the charging region Q0. At the latent image writing position Q1, exposure scanning is performed by the laser beam L of the ROS (electrostatic latent image forming apparatus) to form an electrostatic latent image. When forming a full color image, electrostatic latent images corresponding to four color images of Y (yellow), M (magenta), C (cyan), and K (black) are sequentially formed. Only the electrostatic latent image corresponding to the (black) image is formed.
In the latent image writing with the laser beam L on the surface of the image carrier PR, the belt position sensor SNb detects the reference mark Bm provided on the non-image portion of the intermediate transfer belt (powder carrier, transfer material) B. It starts after a predetermined time has elapsed. In the case of a full-color image, since the respective colors are superimposed, the time from the detection of the reference mark Bm by the belt position sensor SNb to the start of latent image writing by the laser beam L is the same for each color.
The surface of the image carrier PR on which the electrostatic latent image is formed rotates and moves sequentially through the development area Q2 and the primary transfer area (transfer position) Q3.

The rotary developing device D is a toner (powder) of each color of Y (yellow), M (magenta), C (cyan), and K (black) that sequentially rotates and moves to the developing area Q2 as the rotation axis Da rotates. Have developing units DY, DM, DC, and DK. Each of the developing devices DY, DM, DC, and DK of each color has a developing roll DR that conveys the developer to the developing area Q2, and the electrostatic latent image on the image carrier PR that passes through the developing area Q2. Is developed into a toner image Tn.
The toner image Tn developed on the surface of the image carrier PR is primarily transferred to the intermediate transfer belt B by a primary transfer roll (transfer device) T1 in the primary transfer region Q3. In the case of a full-color image, the toner images of the respective colors that are sequentially formed on the surface of the image carrier PR are primarily transferred to the surface of the intermediate transfer belt B in the primary transfer region Q3. The primary transfer roll T1 is supplied with a primary transfer voltage having a polarity opposite to the charging polarity of the toner in the developing device D from a power supply circuit E, and the power supply circuit E is controlled by a controller C.
After the primary transfer, on the surface of the image carrier PR, the residual toner (transfer residual toner) is cleaned by the image carrier cleaner (cleaning device) CL1 in a cleaning region (region facing the image carrier cleaner CL1) Q4. Static electricity is removed by JR.

Below the image carrier PR, a slide frame F1 (indicated by a two-dot chain line) is supported by a pair of left and right slide rails SR, SR so as to be slidable back and forth (in the X-axis direction). A belt frame F2 of the belt module BM is supported on the slide frame F1 so as to be rotatable around the hinge axis F2a.
The belt module F2 includes a belt support roll (Rd, Rt, Rw, Rf) including the intermediate transfer belt B, a belt drive roll Rd, a tension roll Rt, a walking roll Rw, an idler roll (free roll) Rf, and a backup roll T2a. , T2a) and a primary transfer roll T1. The intermediate transfer belt B is supported by the belt support rolls (Rd, Rt, Rw, Rf, T2a) so as to be rotatable in the arrow Yb direction.

The belt module BM rotates about the hinge axis F2a, and a use position where the intermediate transfer belt B contacts the image carrier PR (position where an image forming operation is performed at the position shown in FIG. 1) and a maintenance position. The intermediate transfer belt B can be moved up and down between the positions where the intermediate transfer belt B is separated from the image carrier PR and where maintenance work such as entering and leaving the image forming apparatus main body is performed (not shown).
When the belt module BM is rotated to the maintenance position, the slide frame F1 and the belt module F2 supported by the slide frame F1 are moved in and out of the image forming apparatus main body without being brought into frictional contact with the image carrier PR. It is comprised so that it can be made to.
Such a configuration for moving the slide frame F1 back and forth and a configuration for moving the belt module F2 up and down are conventionally known (see, for example, Japanese Patent Laid-Open No. 8-171248), and various conventionally known configurations are employed. Is possible.

  A secondary transfer roll T2b is disposed opposite to the surface of the intermediate transfer belt B in contact with the backup roll T2a, and a secondary transfer area Q5 is formed in an area where the intermediate transfer belt B and the secondary transfer roll T2b are opposed to each other. Is done. The contract roll T2c is in contact with the backup roll T2a. A secondary transfer voltage having the same polarity as the charging polarity of the toner is applied to the control roll T2c at a predetermined timing from the power supply circuit E controlled by the controller C. The backup roll T2a, the secondary transfer roll T2b, and the contact roll T2c constitute a secondary transfer device T2.

When forming a full-color image, an electrostatic latent image of the first color is formed at the latent image writing position Q1, and a toner image Tn of the first color is formed in the development region Q2. The toner image Tn is electrostatically primarily transferred onto the intermediate transfer belt B by the primary transfer roll T1 when passing through the primary transfer region Q3. Thereafter, similarly, the second, third, and fourth color toner images Tn are sequentially superimposed on the intermediate transfer belt B carrying the first color toner image Tn, and finally transferred to a full color. Are formed on the intermediate transfer belt B.
In the case of forming a monochromatic monochromatic image, only one developing device is used, and the monochromatic toner image is primarily transferred onto the intermediate transfer belt B.

The recording sheets (paper, transfer material) S accommodated in the paper feed tray TR1 are taken out by the pick-up roll Rp at a predetermined timing, separated one by one by the separating roll Rs, and conveyed to the registration roll Rr. The recording sheet S conveyed to the registration roll Rr is subjected to the secondary transfer from the pre-transfer sheet guide SG1 at the timing when the primary-transferred multiple toner image or single-color toner image moves to the secondary transfer area Q5. It is conveyed to area Q5.
In the secondary transfer area Q5, the secondary transfer unit T2 electrostatically secondary-transfers the toner image on the intermediate transfer belt B onto the recording sheet S. A belt cleaner (cleaning device) CL2 is disposed on the downstream side in the rotation direction of the intermediate transfer belt B from the secondary transfer region Q5. A belt cleaning region Q6 is formed at a contact portion between the belt cleaner CL2 and the intermediate transfer belt B. The toner remaining on the surface of the intermediate transfer belt B after the secondary transfer is conveyed to the belt cleaning area Q6 as the intermediate transfer belt B rotates. In the belt cleaning area Q6, the residual toner on the surface of the intermediate belt B is removed by the belt cleaner CL2. The secondary transfer roll T2b collects surface adhering toner by a secondary transfer roll cleaner CL3.

The secondary transfer roll T2b and the belt cleaner CL2 are disposed so as to be separated from (contacted with and separated from) the intermediate transfer belt B. When a color image is formed, an unfixed toner image of the final color is formed. Is separated from the intermediate transfer belt B until it is primarily transferred to the intermediate transfer belt B. The secondary transfer roll cleaner CL3 moves away from and in contact with the secondary transfer roll T2b.
The recording sheet S on which the toner image has been secondarily transferred is conveyed to the fixing region Q7 by the post-transfer sheet guide SG2 and the sheet conveying belt BH, and is heated and fixed by the fixing device F when passing through the fixing region Q7. The recording sheet S on which the toner image is fixed is discharged to the recording sheet discharge tray TRh.
A sheet conveying device SH is constituted by the elements indicated by the symbols Rp, Rs, Rr, SG1, SG2, and BH.

(Belt cleaner CL2)
FIG. 2 is an explanatory diagram of the belt cleaner according to the first embodiment.
In FIG. 2, the belt cleaner (cleaning device) CL2 has a toner recovery container (cleaning case) 1 having an opening formed at a position facing the intermediate transfer belt B. A first cleaning brush 2a and a second cleaning brush 2b are rotatably supported on the toner recovery container 1. The first cleaning brush 2a and the second cleaning brush 2b are in contact with the intermediate transfer belt B with a predetermined amount of biting. The second cleaning brush 2b is disposed downstream of the first cleaning brush 2a in the moving direction of the intermediate transfer belt B. The first cleaning brush 2a and the second cleaning brush 2b are rotated in opposite directions at a contact portion with the intermediate transfer belt B by a cleaning brush driving device (not shown).

A first belt cleaning region Q6a is formed by a contact portion between the first cleaning brush 2a and the intermediate transfer belt B. A contact portion between the second cleaning brush 2b and the intermediate transfer belt B forms a second belt cleaning region Q6b. The first belt cleaning region Q6a and the second belt cleaning region Q6b form the belt cleaning region Q6.
The first cleaning brush 2a is applied with a positive first cleaning brush bias V1 by a first cleaning brush voltage supply circuit E1 as a belt cleaning bias supply device. The second cleaning brush 2b is applied with a negative second cleaning brush bias V2 by a second cleaning brush voltage supply circuit E2 as a belt cleaning bias supply device.

  A first detoning roll (electrostatic attracting member) 3a contacts the first cleaning brush 2a with a predetermined biting amount on the downstream side of the first belt cleaning region Q6a in the brush rotation direction. A first brush cleaning region Q8a is formed by a contact portion between the first cleaning brush 2a and the first detoning roll 3a. The first detoning roll 3a is rotated in the same direction as the first cleaning brush 2a by a detoning roll driving device (not shown) in the first brush cleaning region Q8a. The first detoning roll 3a is a first detoning having the same polarity (positive polarity) as the first cleaning brush bias V1 by a first detoning roll voltage supply circuit E3 as a brush cleaning bias supply device. A roll bias V3 is applied. The first detoning roll bias V3 is set to be larger than the first cleaning brush bias V1 (V1 <V3).

The second detoning roll (electrostatic attracting member) 3b comes into contact with the second cleaning brush 2b with a predetermined biting amount on the downstream side of the second belt cleaning region Q6b in the brush rotation direction. A second brush cleaning region Q8b is formed by a contact portion between the second cleaning brush 2b and the second detoning roll 3b. The second detoning roll 3b is rotated in the same direction as the second cleaning brush 2b by a detoning roll driving device (not shown) in the second brush cleaning region Q8b. The second detoning roll 3b is a second detoning having the same polarity (negative polarity) as the second cleaning brush bias V2 by a second detoning roll voltage supply circuit E4 as a brush cleaning bias supply device. A roll bias V4 is applied. The absolute value of the second detoning roll bias V4 is set to be larger than the absolute value of the second cleaning brush bias V2 (| V2 | <| V4 |).
A brush cleaning region Q8 is formed by the first brush cleaning region Q8a and the second brush cleaning region Q8b.

The first scraper 4a is in contact with the first detoning roll 3a with a predetermined bite amount on the downstream side of the first brush cleaning region Q8a in the roll rotation direction. The first scraper 4 a is supported by a first scraper support member 6 a fixed at the left end (−Y direction end) to the toner recovery container 1.
The second scraper 4b is in contact with the second detoning roll 3b with a predetermined bite amount on the downstream side in the roll rotation direction with respect to the second brush cleaning region Q8b. The second scraper 4b is supported by a second scraper support member 6b fixed to the toner recovery container 1 at both front and rear ends (X-axis direction both ends).
The first scraper support member 6a and the second scraper support member 6b are arranged such that the first scraper 4a and the second scraper 4b abut on the first detoning roll 3a and the second detoning roll 3b at a set angle θ. It is supported by.
Below the first scraper 4a and the second scraper 4b, a toner conveying auger 7 is provided for carrying residual toner to a waste toner collecting device (not shown).

The first cleaning brush 2a and the second cleaning brush 2b constitute the cleaning brush 2 of the belt cleaner CL2 of the first embodiment.
The first detoning roll 3a and the second detoning roll 3b constitute a detoning roll (electrostatic attracting member) 3 of the belt cleaner CL2 of the first embodiment.
The first scraper 4a and the second scraper 4b constitute the scraper 4 of the belt cleaner CL2 of the first embodiment.
The belt cleaner (cleaning device) CL2 of Example 1 is constituted by the toner collecting container 1, the cleaning brush 2, the detoning roll 3, the scraper 4, the first scraper support member 6a, the second scraper support member 6b, and the toner transport auger 7. Is configured.

(Operation of Example 1)
In the image forming apparatus U of Embodiment 1 having the above-described configuration, the toner image on the intermediate transfer belt B is secondarily transferred to the recording sheet S by the secondary transfer unit T2 when passing through the secondary transfer region Q4. . Residual toner after secondary transfer adhering to the surface of the intermediate transfer belt B is conveyed to the belt cleaning region Q6 as the intermediate transfer belt B rotates.
The residual toner conveyed to the belt cleaning area Q6 is scraped off from the intermediate transfer belt B by the first cleaning brush 2a and the second cleaning brush 2b that come into contact with the intermediate transfer belt B with a predetermined amount of biting. At this time, since the positive first cleaning brush bias V1 is applied to the first cleaning brush 2a, the negatively charged residual toner is adsorbed. Further, since the second cleaning brush bias V2 having the negative polarity is applied to the second cleaning brush 2b, the residual toner charged to the positive polarity is adsorbed. Therefore, the residual toner adhering to the intermediate transfer belt B is adsorbed to the first cleaning brush 2a or the second cleaning brush 2b regardless of whether the toner is positively charged or negatively charged.

The negative residual toner adsorbed on the first cleaning brush 2a moves to the first brush cleaning region Q8a as the first cleaning brush 2a rotates. The negative residual toner is applied with a first detoning roll bias V3 having a positive polarity (V1 <V3) larger than the first cleaning brush bias V1 in the first brush cleaning region Q8a. It moves electrostatically to the detoning roll 3a. The residual toner moved to the first detoning roll 3a is removed from the surface of the first detoning roll 3a by receiving a mechanical scraping force by the first scraper 4a.
The positive residual toner adsorbed on the second cleaning brush 2b moves to the second brush cleaning region Q8b as the second cleaning brush 2b rotates. The positive residual toner is applied with a second detoning roll bias V4 having a negative polarity (| V2 | <| V4 |) greater than the second cleaning brush bias V2 in the second brush cleaning region Q8b. The second detoning roll 3b is moved electrostatically. The residual toner moved to the second detoning roll 3b is removed from the surface of the second detoning roll 3b by receiving a mechanical scraping force by the second scraper 4b.
The residual toner scraped off by the first scraper 4a and the second scraper 4b is transported by a toner transport auger 7 to a waste toner collecting device (not shown).
Thus, the residual toner on the surface of the intermediate transfer belt B after the secondary transfer is removed by the belt cleaner CL2. Therefore, when an image is recorded on the recording paper S, it is possible to prevent image quality degradation caused by the residual toner.

(Experimental Example 1: Residual toner scraping test on intermediate transfer belt surface)
Based on the configuration of Example 1, a residual toner scraping test on the surface of the intermediate transfer belt was performed as Experimental Example 1.
In Experimental Example 1, the Ti-based external additive (volume resistivity 11.3 log Ωcm) for improving the fluidity and chargeability of the toner is 1.0%, and the Ti-based external additive for improving the chargeability. A toner to which 0.4% of (volume resistivity 11.2 log Ωcm) is added is used.
(First cleaning brush 2a)
As the first cleaning brush 2a, one having an outer diameter of 14 mm, a shaft diameter of 6 mm, a pile height of 3.5 mm, and an amount of biting into the intermediate transfer belt of 1 mm was used.
The brush hair of the first cleaning brush 2a is made of nylon, and the brush bristle has a volume resistivity of 8, 10, 12 log Ωcm, and has a thickness of 2, 4, 6 denier. Any one of those having a density of 120,000, 240,000, 430,000 / inch ² was used. Further, 400 V as a first cleaning brush bias V1 was applied to the first cleaning brush 2a.
The combination of the thickness and density of the brush hair will be described later with reference to FIG. The volume resistivity of the bristle is a value calculated from a current value when a voltage of 150 V is applied to the bristle.

(Second cleaning brush 2b)
As the second cleaning brush 2b, one having an outer diameter of 10 mm, a shaft diameter of 5 mm, a pile height of 2 mm, and an amount of biting into the intermediate transfer belt of 1 mm is used.
Further, the brush hair of the second cleaning brush 2b is made of nylon, has a volume resistivity of 8, 10, 12 log Ωcm, and has a thickness of 2, 4, 6 denier. One having a density of 120,000, 240,000, 430,000 / inch ² was used.
Further, −400 V as the second cleaning brush bias V2 was applied to the second cleaning brush 2b.
(First detoning roll 3a)
As the first detoning roll 3a, a material whose surface is aluminum whose surface is subjected to a taffram treatment, an outer diameter of 14 mm, and an amount of biting into the first cleaning brush 2a is 1 mm.
Further, 1000 V as a first detoning roll bias V3 was applied to the first detoning roll 3a.

(Second detoning roll 3b)
The second detoning roll 3b is made of aluminum whose surface is subjected to a turfrum treatment, the outer diameter is 10 mm, and the amount of biting into the second cleaning brush 2b is 1 mm.
Further, −1000 V as a second detoning roll bias V4 was applied to the second detoning roll 3b.
(First scraper 4a)
The first scraper 4a has a thickness of 80 μm, a free length of 8 mm, a material of SUS plate (Stainless Used Steel, stainless steel), an amount of biting into the first detoning roll 2a, and a first detoning roll 2a. The contact angle θ with respect to is 32 degrees.
(Second scraper 4b)
The second scraper 4b has a thickness of 80 μm, a free length of 8 mm, a material of SUS plate, an amount of biting into the second detoning roll 2b of 1.3 mm, and a contact angle θ with the second detoning roll 2b. It is 32 degrees.

FIG. 3 is a diagram showing the tip force of the cleaning brush, and is a diagram showing the relationship between the thickness and density of the brush hair of the cleaning brush.
In FIG. 3, the tip force of the cleaning brush 2 is 0 when the bristle thickness is set to 2 denier and the brush bristle density is changed to 120,000, 240,000 and 430,000 / inch ^2. 0.08, 0.11, 0.36 gf / mm. Further, the tip force of the cleaning brush 2 was 0.2 gf / mm when the thickness of the bristle was set to 4 denier and the bristle density was set to 120,000 / inch ² . The tip force of the cleaning brush 2 was 0.32 gf / mm when the brush hair thickness was set to 6 denier and the brush hair density was set to 120,000 / inch ² Note that the intermediate transfer after the secondary transfer The tip force of the cleaning brush 2 as a force for scraping off the toner remaining on the surface of the belt B is 2 mm / sec with a cleaning brush 2 set to a 1 mm bite amount on a 2 mm wide contact attached to a load cell. This is the load when rotating.

FIG. 4 is a diagram showing the cleaning performance of the belt cleaner when a toner to which an external additive having a relatively low resistance is added. The horizontal axis indicates the cleaning brush tip force, and the vertical axis indicates the volume of the brush hair. It is the graph which took the resistivity.
As Experimental Example 1, using a toner to which an external additive having a relatively low resistance of about 11 log Ωcm was added under the above-described conditions, the volume resistance of the brush bristles with respect to the cleaning brush having each tip force shown in FIG. When the rate was 8, 10 and 12 log Ωcm, a test was performed to determine whether the residual toner was sufficiently scraped off from the intermediate transfer belt B.
In FIG. 4, in the residual toner scraping test on the surface of the intermediate transfer belt B, sufficient cleaning performance was exhibited under the following conditions (1) to (4).
(1) Tip force of cleaning brush 2 0.32 gf / mm, volume resistivity of brush hair 10 logΩcm
(2) Tip force of cleaning brush 2 0.32 gf / mm, volume resistivity of brush hair 12 logΩcm
(3) Tip force of cleaning brush 2 0.36 gf / mm, volume resistivity of brush hair 10 logΩcm
(4) Tip force of cleaning brush 2 0.36 gf / mm, volume resistivity of brush hair 12 logΩcm
From this result, by setting the tip force of the cleaning brush 2 to about 0.3 gf / mm or more and the volume resistivity of the brush hair to 10 logΩcm or more, the toner to which a relatively low resistance external additive of about 11 logΩcm is added is added. It can be seen that sufficient cleaning performance can be exhibited even when using.

(Experimental example 2: Toner transfer test from cleaning brush to detoning roll)
FIG. 5 is a diagram showing a bias applied to the cleaning brush and the detoning roll in the toner movement test from the cleaning brush to the detoning roll. The horizontal axis indicates the bias difference between the cleaning brush and the detoning roll. Is a graph in which the applied bias is taken on the vertical axis.
Based on the configuration of Example 1, a toner transfer test from the cleaning brush to the detoning roll was performed as Experimental Example 2. In Experimental Example 2, as in Experimental Example 1, a toner to which an external additive having a relatively low resistance of about 11 log Ωcm was added was used.
In FIG. 5, when the absolute values of the first cleaning brush bias V <b> 1 and the second cleaning brush bias V <b> 2 applied to the cleaning brush 2 are 400 V, the first detoning roll bias applied to the detoning roll 3. By setting the absolute value of V3 and the second detoning roll bias V4 to any of 600V, 800V, 1000V, and 1200V, the bias difference (| V3-V1 |, | V4-V2 |) is set to 200V, 400V, It was set to 600V and 800V.
When the absolute values of the first cleaning brush bias V1 and the second cleaning brush bias V2 applied to the cleaning brush 2 are 800 V, the first detoning roll bias V3 applied to the detoning roll 3 and By setting the absolute value of the second detoning roll bias V4 to any one of 1000V, 1200V, 1400V, and 1600V, the bias difference (| V3-V1 |, | V4-V2 |) is set to 200V, 400V, 600V, Set to 800V.

(Experimental example 2-1: When the volume resistivity of the brush hair is 10 logΩcm)
FIG. 6 is a graph showing the results of a toner transfer test from a cleaning brush having a brush hair volume resistivity of 10 log Ωcm to a detoning roll. The horizontal axis represents the bias difference between the cleaning brush and the detoning roll, and the vertical axis represents the result. 6 is a graph showing the amount of toner remaining in a cleaning brush.
In FIG. 6, Experimental Example 2-1 performed a toner transfer test from a cleaning brush having a brush hair volume resistivity of 10 log Ωcm to a detoning roll.
Experimental Example 2-1 was performed using the cleaning brush 2 under the following conditions (1) and (2).
(1) Thickness 2 denier, density 430,000 / inch ²
(2) Thickness 6 denier, density 120,000 / inch ²
In FIG. 6, in Example 2-1, the amount of toner remaining on the cleaning brush 2 was set to 0.02 g / m ² or less as a target value. As shown in FIG. 6, the bias difference (| V3-V1 |) between the first cleaning brush bias V1 and the first detoning roll bias V3, and the second cleaning brush bias V2 and the third detoning roll. An experimental result was obtained that cleared the target value when the bias difference (| V4−V2 |) with the bias V4 for use was 600V or more.

(Experimental example 2-2: When the volume resistivity of the brush hair is 12 log Ωcm)
FIG. 7 is a graph showing the results of a toner transfer test from a cleaning brush having a brush hair volume resistivity of 12 log Ωcm to a detoning roll. The horizontal axis represents the bias difference between the cleaning brush and the detoning roll, and the vertical axis represents the result. 6 is a graph showing the amount of toner remaining in a cleaning brush.
In FIG. 7, in Example 2-2, a toner transfer test from a cleaning brush having a brush hair volume resistivity of 12 log Ωcm to a detoning roll was performed.
Experimental Example 2-2 was performed using the cleaning brush 2 under the following conditions (1) and (2).
(1) Thickness 2 denier, density 430,000 / inch ²
(2) Thickness 6 denier, density 120,000 / inch ²
In FIG. 7, in Example 2-2, the amount of toner remaining on the cleaning brush 2 is set to 0.02 g / m ² or less as a target value. As shown in FIG. 7, the absolute value (| V3-V1 |) of the bias difference between the first cleaning brush bias V1 and the first detoning roll bias V3, and the second cleaning brush bias V2 and the third bias. When the absolute value (| V4-V2 |) of the bias difference from the detoning roll bias V4 is 600 V or more, an experimental result that clears the target value was obtained.

5 to 7, when the cleaning brush 2 having the bristle whose volume resistivity is 10 Ωcm or more is used from the result of the toner transfer test from the cleaning brush to the detoning roll as Experimental Example 2, If the bias difference (| V3-V1 |, | V4-V2 |) between the brush 2 and the detoning roll 3 is 600 V or more, the toner can be sufficiently moved from the cleaning brush 2 to the detoning roll 3. all right.
Further, it was found that when the bias difference between the cleaning brush 2 and the detoning roll 3 is insufficient (less than 600 V), toner remains between the brush hairs of the cleaning brush 2. In the state where the toner remains between the brush hairs, an electric field that attracts the residual toner scraped off from the intermediate transfer belt B is less likely to be generated, and at the same time, the amount of toner that can be included between the brush hairs is reduced. There is a problem that the cleaning property is lowered.

FIG. 8 is a graph showing the characteristics of the belt cleaner. FIG. 8A is a graph in which the horizontal axis indicates the tip force of the cleaning brush, and the vertical axis indicates the amount of toner scraped off. FIG. Fig. 8C is a graph in which the residual toner amount between the brush hairs is plotted on the vertical axis, and the residual toner amount between the brush hairs is plotted on the horizontal axis, and the cleaning performance of the cleaning brush is plotted on the vertical axis. It is a graph taken.
In FIG. 8A, the relationship between the tip force of the cleaning brush and the amount of toner scraped is generally that when the tip force of the cleaning brush 2 is increased, the amount of toner scraped off by the cleaning brush 2 increases. Are known.
In FIG. 8B, the relationship between the bias difference between the cleaning brush and the detoning roll and the residual toner amount between the brush hairs indicates that the residual toner between the brush hairs increases when the bias difference between the cleaning brush 2 and the detoning roll 3 is increased. It is generally known that the amount is reduced.
In FIG. 8C, the relationship between the residual toner amount between the brush hairs and the cleaning performance of the cleaning brush is that the cleaning brush 2 that removes the residual toner on the surface of the intermediate transfer belt B when the residual toner amount between the brush hairs increases. It is generally known that performance is reduced.

From the results of the experimental examples 1 and 2, the belt cleaner (cleaning device) CL2 of the present invention has a high cleaning brush resistance (volume resistivity of 10 log Ωcm or more) and a high brush tip force (tip force 0.3 gf / mm), the residual toner adhering to the surface of the intermediate transfer belt B after the secondary transfer is sufficiently removed even when a toner to which a relatively low resistance external additive of 11 log Ωcm or less is used is used. Can be removed.
Further, when a toner to which an external additive having a relatively low resistance of 11 log Ωcm or less is used, the bias difference between the cleaning brush 2 and the detoning roll 3 is set to 600 V or more, whereby the brush of the cleaning brush 2 is used. It is possible to prevent the toner from remaining more than 0.02 g / m ² between the hairs. Therefore, the belt cleaner CL2 of the present invention can maintain the cleaning performance for sufficiently cleaning the intermediate transfer belt B.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to each said Example 1, In the range of the summary of this invention described in the claim, various changes are made. Can be done. Modified examples (H01) to (H03) of the present invention are exemplified below.
(H01) In the first embodiment, it is desirable that the residual toner adsorbed on the cleaning brush 2 is electrostatically moved by the detoning roll 3, but a plate-like member (flicker bar or the like) is brought into contact with the cleaning brush. It is also possible to mechanically scrape off the toner between the brush hairs.
(H02) In the first embodiment, the belt cleaner CL2 is exemplified as the cleaning device. However, the present invention is not limited to this, and the cleaning device CL2 can also be applied to the image carrier cleaner CL1 and the secondary transfer roll cleaner CL3. . Further, the cleaning device CL2 can be applied to a member that cleans a document transport roll that transports the document Gi. In this case, paper dust generated from the edge of the original document Gi can be removed.
(H03) In the first embodiment, the voltage applied to the cleaning brush 2 can be either positive polarity or negative polarity according to the charging polarity of the toner to be used.

FIG. 1 is an overall explanatory view of an image forming apparatus provided with a cleaning device of the present invention. FIG. 2 is an explanatory diagram of the belt cleaner according to the first embodiment. FIG. 3 is a diagram showing the tip force of the cleaning brush, and is a diagram showing the relationship between the thickness and density of the brush hair of the cleaning brush. FIG. 4 is a diagram showing the cleaning performance of the belt cleaner when a toner to which an external additive having a relatively low resistance is added. The horizontal axis indicates the cleaning brush tip force, and the vertical axis indicates the volume of the brush hair. It is the graph which took the resistivity. FIG. 5 is a diagram showing a bias applied to the cleaning brush and the detoning roll in the toner movement test from the cleaning brush to the detoning roll. The horizontal axis indicates the bias difference between the cleaning brush and the detoning roll. Is a graph in which the applied bias is taken on the vertical axis. FIG. 6 is a graph showing the results of a toner transfer test from a cleaning brush having a brush hair volume resistivity of 10 log Ωcm to a detoning roll. The horizontal axis represents the bias difference between the cleaning brush and the detoning roll, and the vertical axis represents the result. 6 is a graph showing the amount of toner remaining in a cleaning brush. FIG. 7 is a graph showing the results of a toner transfer test from a cleaning brush having a brush hair volume resistivity of 12 log Ωcm to a detoning roll. The horizontal axis represents the bias difference between the cleaning brush and the detoning roll, and the vertical axis represents the result. 6 is a graph showing the amount of toner remaining in a cleaning brush. FIG. 8 is a graph showing the characteristics of the belt cleaner. FIG. 8A is a graph in which the horizontal axis indicates the tip force of the cleaning brush, and the vertical axis indicates the amount of toner scraped off. FIG. Fig. 8C is a graph in which the residual toner amount between the brush hairs is plotted on the vertical axis, and the residual toner amount between the brush hairs is plotted on the horizontal axis, and the cleaning performance of the cleaning brush is plotted on the vertical axis. It is a graph taken.

Explanation of symbols

2 ... Cleaning brush,
3 ... Electrostatic adsorption member,
4 ... scraper,
B: Powder carrier, intermediate transfer belt,
CL2 ... cleaning device,
E3, E4 ... voltage application device for adsorption,
Q8 ... contact part,
V3, V4 ... voltage for adsorption,

Claims (5)

A cleaning device comprising the following structural requirements (A01) and (A02):
(A01) a powder carrier that carries powder on its surface;
(A02) A cleaning brush to which a cleaning electric field is applied for electrostatically removing the powder adhering to the surface of the powder carrier, wherein the bristle resistance of the brush hair is 10 log Ωcm or more and the brush tip force is 0 The cleaning brush of 3 gf / mm or more. The cleaning device according to claim 1, comprising the following configuration requirements (A03):
(A03) The powder composed of toner. The cleaning device according to claim 2, comprising the following configuration requirement (A04):
(A04) The toner containing an external additive having a resistance value of 11 log Ωcm or less. The cleaning device according to any one of claims 1 to 3, further comprising the following constituent elements (A05) and (A06):
(A05) An electrostatic adsorption member disposed in contact with the cleaning brush and electrostatically adsorbing and removing powder from the cleaning brush;
(A06) An adsorption voltage applying device that applies an adsorption voltage to the electrostatic adsorption member so that a potential difference between the cleaning brush and the electrostatic adsorption member is 600 V or more. The cleaning device according to any one of claims 1 to 4, further comprising the following structural requirements (A07) and (A08):
(A07) the powder carrier constituted by an intermediate transfer belt;
(A08) A scraper that abuts on the electrostatic adsorption member and scrapes the powder adsorbed on the surface of the electrostatic adsorption member.

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