JP2017049341A - Cleaning device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device that can maintain excellent cleaning performance for a long period.SOLUTION: There is used a cleaning device 200 comprising: a removal roller 201 that removes a residual toner and a foreign substance derived from a sheet from an image carrier 132; a recovery roller 202 that recovers the residual toner and foreign substance from the removal roller 201; a blade 204 that separates the residual toner and foreign substance from the recovery roller 202; a discharge part 205 that discharges the residual toner and foreign substance separated from the recovery roller 202; and a sheet 203 that is disposed between the removal roller 201 and discharge part 205 and has its one end in contact with a surface of the recovery roller 202. The amount of the removal roller 201 biting into the image carrier 132 and the surface roughness of the recovery roller 202 decrease as time for image formation increases.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cleaning device and an image forming apparatus.

  An image forming apparatus using an electrophotographic system, such as a copying machine, a printer, a facsimile machine, and a composite machine thereof, includes a photosensitive member, a charging device that uniformly charges the surface of the photosensitive member, and a charged photosensitive member. An exposure device that forms an electrostatic latent image on the surface of the photosensitive member by exposing the surface of the photosensitive member; and supplying toner to the surface of the photosensitive member on which the electrostatic latent image is formed. The image forming apparatus includes a developing device that develops an image as a toner image, a transfer device that transfers the image onto a sheet or the like, and a fixing device that fixes the transferred toner image on the sheet or the like.

  The image forming apparatus further includes a cleaning device that removes toner remaining on the image carrier, so-called residual toner, from the image carrier after transferring the toner image on the image carrier such as a photosensitive member or an intermediate transfer belt to paper or the like. ing. By doing so, it is possible to suppress deterioration in the image quality of the formed image due to the toner that remains on the image carrier without being transferred.

  As such a cleaning device, first, a so-called blade cleaning method in which a blade is directly applied to an image carrier and the toner is mechanically stopped. This type of cleaning device has been employed in cleaning devices for intermediate transfer belts that do not have an elastic layer, such as a photosensitive member or a polyimide intermediate transfer belt, for the reason that the configuration is simple and inexpensive. Further, for an image carrier having an elastic layer, a method of mechanically and electrically removing residual toner from the image carrier with a cleaning brush such as a fur brush has been employed. Examples of this type of cleaning device include a system in which residual toner removed by a cleaning brush is recovered by a recovery roller, and then a blade is applied to the recovery roller to recover the residual toner.

  As a cleaning device used in the image forming apparatus, for example, a cleaning device described in Patent Document 1 can be cited.

  In Patent Document 1, a plate-like elastic blade that comes into contact with a rotationally movable image carrier and removes residual toner on the surface of the image carrier, and residual toner that has been removed and taken into the cleaning device casing are predetermined. A cleaning device having a rotatable waste toner transfer means for transferring to a different location. In this cleaning device, a seal member is disposed in contact with the surface of the image carrier, on the upstream side in the rotation direction of the image carrier relative to a contact portion between the elastic blade and the image carrier, and the seal member includes: An end opposite to the contact portion with the image carrier is engaged with an inner wall of the cleaning device casing within a projection area range immediately below the waste toner transfer means in the cleaning device, and a flat portion of the seal member Is movable in the vertical direction.

JP 2008-96630 A

  According to Patent Document 1, it is disclosed that residual toner is prevented from leaking out of the cleaning device by a sealing member disposed in contact with the surface of the image carrier. Further, it is disclosed that there is no toner accumulation in the vicinity of the housing opening where the residual toner falls, and that the toner can be stably recovered.

  The cleaning device described in Patent Document 1 is a so-called blade cleaning type cleaning device. Even if the sealing member provided in this cleaning device is applied to a cleaning device that mechanically and electrically removes residual toner with a cleaning brush, the residual toner removed with the cleaning brush is not transferred to the image carrier side. In some cases, leakage could not be sufficiently suppressed.

  This is considered to be due to the following.

  First, not only residual toner but also foreign matters derived from paper such as paper dust are present on the image carrier. Accordingly, not only the residual toner but also foreign matters derived from the paper are removed by the cleaning device.

  When the foreign material derived from the paper is removed by the cleaning device, the foreign material derived from the paper enters between the seal member and the image carrier, and a gap is formed between the seal member and the image carrier. It is believed that there is. From this, even if there is a seal member, it is considered that the residual toner removed by the cleaning brush may not be sufficiently prevented from leaking to the image carrier side. In such a case, it is considered that excellent cleaning performance cannot be maintained over a long period of time.

  This invention is made | formed in view of this situation, Comprising: It aims at providing the cleaning apparatus which can maintain the outstanding cleaning performance over a long period of time. Another object of the present invention is to provide an image forming apparatus including the cleaning device.

  As a result of investigation by the present inventor, it was inferred that the reason why the residual toner removed by the cleaning brush cannot sufficiently be prevented from leaking to the image carrier side even if there is a seal member.

  Specifically, a cleaning device that mechanically and electrically removes residual toner with a cleaning brush, specifically, a removal roller such as a fur brush is brought into contact with the surface of the image carrier to leave the residual from the image carrier. Remove toner. The toner removed from the image carrier is collected on the collection roller by bringing the collection roller into contact with the surface of the removal roller. Then, the collected residual toner is separated from the collection roller by a blade brought into contact with the surface of the collection roller, and the separated residual toner is discharged by a discharge unit. At that time, in order to prevent the separated residual toner from returning to the image carrier side, a sheet is provided between the removal roller and the discharge portion so that one end thereof is in contact with the surface of the collection roller. May be placed.

  The image carrier transports not only residual toner but also foreign matters derived from paper such as paper dust. Paper dust, which is such foreign matter, is also removed from the image carrier by a removal roller, as with residual toner. At that time, the residual toner is considered to be charged from the paper powder. From this, it is considered that the power adhering to the collecting roller is weaker than that of the residual toner. Therefore, when the sheet is provided, it is considered that paper dust is less likely to pass between the sheet and the collection roller than the residual toner. And it is thought that such paper dust will be accumulate | stored gradually in the rotation direction upstream of the collection | recovery roller of a sheet | seat. When such accumulation proceeds, it is considered that paper dust enters between the sheet and the collection roller, and a gap is formed between the sheet and the collection roller. As described above, it is considered that the sheet in which the gap is formed between the collecting roller and the recovery roller cannot sufficiently suppress the leakage of the residual toner to the image carrier side. As described above, it was assumed that leakage of residual toner to the image carrier side may not be sufficiently suppressed by simply providing a sheet.

  Therefore, the present inventor considered that foreign matters such as paper dust can smoothly pass between the sheet and the collection roller by increasing the conveying force of foreign matters such as paper dust by the collection roller.

  However, it has been found that the blade may be damaged even if foreign matter can smoothly pass between the sheet and the collection roller only by using the collection roller that simply increases the conveyance force in this way. . In particular, it has been found that when image formation is performed over a long period of time, damage to the blade becomes more prominent and separation of residual toner from the collection roller by the blade may not be suitably performed.

  On the other hand, it has been found that foreign matters such as paper dust conveyed from the image carrier gradually decrease when image formation is performed over a long period of time, since the conveyance force of the image carrier gradually decreases. It was.

  From these facts, in view of the fact that the amount of foreign matter decreases with an increase in image formation time, the present inventor has the ability to remove residual toner from the image carrier by the removal roller as the image formation time increases. The inventors have arrived at the present invention as described below, in which the conveying force of the collection roller is reduced.

  A cleaning device according to an aspect of the present invention is a cleaning device provided in an image forming apparatus, and contacts a surface of an image carrier provided in the image forming apparatus so that a toner image on the image carrier is applied to a sheet. Residual toner remaining on the image carrier after being transferred and a removal roller for removing foreign matters derived from the paper from the image carrier, and residual toner removed by the removal roller in contact with the surface of the removal roller And a collection roller for collecting the foreign matter, a blade that contacts the surface of the collection roller and separates the residual toner and foreign matter collected by the collection roller from the collection roller, and a residual toner and foreign matter separated from the collection roller Between the removal roller and the discharge portion, with one end contacting the surface of the recovery roller A chromatography bets, the surface roughness of the amount and the recovery roller bite into the removing roller to said image bearing member, characterized in that it decreases with an increase in image forming time.

  According to such a configuration, it is possible to provide a cleaning device that can maintain excellent cleaning performance over a long period of time.

  This is considered as follows.

  First, foreign matters such as paper dust conveyed from the image carrier gradually decrease when the image is formed over a long period of time because the conveyance force of the image carrier gradually decreases. From this, it is possible to suitably remove foreign matters such as paper dust from the image carrier even if the amount of the removal roller biting into the image carrier is gradually reduced as the image formation time increases. . In addition, in order to ensure excellent cleaning performance, the recovery roller having a conveyance force that can sufficiently suppress leakage of residual toner to the image carrier side may damage the blade. In contrast, since the amount of residual toner removed by the removal roller decreases as the image formation time increases, the amount of residual toner remaining on the image carrier side even if the surface roughness of the collection roller is gradually reduced. It is considered that toner leakage can be sufficiently suppressed. As the image forming time increases, the surface roughness of the collection roller is gradually reduced, so that it is considered that damage to the blade is also suppressed. For this reason, it is considered that the removal of residual toner by the blade from the collection roller is also preferably performed over a long period of time. Therefore, it is considered that, according to the above configuration, excellent cleaning performance can be maintained over a long period of time.

  In the cleaning device, it is preferable that the surface roughness of the recovery roller is reduced from 3 to 6 μm to 1.5 to 3 μm in terms of 10-point average roughness.

  According to such a configuration, more excellent cleaning performance can be maintained over a long period of time. This is considered to be due to the following.

  At the beginning of image formation, the surface roughness of the collection roller is 3 to 6 μm in terms of 10-point average roughness, so the conveyance force of the collection roller is high, and leakage of residual toner to the image carrier side can be sufficiently suppressed. it is conceivable that. Further, as the image forming time increases, the surface roughness of the collection roller decreases to 1.5 μm or more and less than 3 μm in terms of 10-point average roughness, so that damage to the blade is sufficiently suppressed. Therefore, it is considered that, according to the above configuration, it is possible to maintain better cleaning performance over a long period of time.

  In the cleaning device, it is preferable that the rebound resilience of the blade is 45 ° or more in international rubber hardness. Further, it is preferable that the blade has a linear pressure with respect to the collection roller of 12 gf / cm or more and a cleaning angle of 12 ° or more.

  According to such a configuration, more excellent cleaning performance can be maintained over a long period of time. This is considered to be due to the following.

  It is considered that the surface roughness of the collecting roller can be suitably reduced as the image forming time increases. In addition, it is considered that residual toner is preferably removed from the recovery roller by a blade. Therefore, it is considered that, according to the above configuration, it is possible to maintain better cleaning performance over a long period of time.

  Further, in the cleaning device, the position of the removal roller in contact with the image carrier is reduced from 1 mm to 0.75 mm in distance from the position when the image carrier is not present. Is preferred.

  According to such a configuration, excellent cleaning performance can be maintained over a longer period. This is considered to be due to the following.

  As the image forming time increases, the amount of the removal roller biting into the image carrier can be suitably reduced as the amount of foreign matter such as paper dust conveyed by the image carrier decreases. . From this, it is considered that the removal roller can suitably remove the residual toner from the image carrier while suppressing the damage caused by the contact between the removal roller and the image carrier. Therefore, it is considered that excellent cleaning performance can be maintained over a longer period.

  Moreover, in the cleaning device, it is preferable that an average interval of the unevenness of the recovery roller is 50 to 150 μm.

  According to such a configuration, excellent cleaning performance can be maintained over a longer period. This is considered to be because the residual toner can be suitably conveyed by the collection roller while suppressing damage to the blade.

  In the cleaning device, it is preferable that the sheet includes a base material and powder disposed in an area of the base material that contacts at least the recovery roller.

  According to such a configuration, the cleaning performance can be further improved. This is considered to be due to the following.

  Such a sheet reduces the adhesion of foreign matter such as paper dust. For this reason, it is thought that foreign materials, such as paper dust, can enter between a collection roller and a sheet. Therefore, it is considered that leakage of residual toner to the image carrier side due to foreign matter such as paper dust entering between the collection roller and the sheet can be sufficiently suppressed. From this, it is considered that the cleaning performance can be further improved.

  In the cleaning device, the base material is preferably a thermoplastic polyurethane sheet.

  According to such a configuration, the cleaning performance can be further improved. This is considered to be due to the following. A sheet provided with such a base material allows foreign matters such as residual toner and paper dust to pass between the collection roller and the sheet, and can sufficiently suppress leakage of residual toner to the image carrier. it is conceivable that. From this, it is considered that the cleaning performance can be further improved.

  In the cleaning device, the removal roller is preferably a fur brush.

  According to such a configuration, it is possible to remove residual toner on the image carrier and foreign matters derived from paper such as paper dust from the image carrier while suppressing damage to the image carrier.

  In the cleaning device, it is preferable that the image carrier is an intermediate transfer member to which the toner image developed by the developing device is transferred and the transferred toner image is transferred to a sheet.

  According to such a configuration, it is possible to suitably remove foreign matters derived from paper such as residual toner and paper dust on the intermediate transfer member.

  An image forming apparatus according to another aspect of the present invention includes the cleaning device.

  According to such a configuration, a high-quality image can be formed over a long period of time. This is considered to be because image quality deterioration due to the presence of residual toner or paper-derived foreign matter can be suitably suppressed over a long period of time.

  ADVANTAGE OF THE INVENTION According to this invention, the cleaning apparatus which can maintain the outstanding cleaning performance over a long period of time can be provided. Further, according to the present invention, an image forming apparatus including the cleaning device is provided.

FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus to which a cleaning device according to an embodiment of the present invention is applied. FIG. 2 is a schematic cross-sectional view showing the configuration of the cleaning device according to the embodiment of the present invention. FIG. 3 is a schematic diagram showing the periphery of the image forming unit of the image forming apparatus to which the cleaning device according to the embodiment of the present invention is applied. FIG. 4 is a diagram for explaining the state of the blade. FIG. 5 is a graph showing the result of the paper dust adhesion of the sheet.

  Hereinafter, although the embodiment concerning the present invention is described, the present invention is not limited to these.

  An image forming apparatus 10 shown in FIG. 1 will be described as an example of an image forming apparatus to which a cleaning device according to an embodiment of the present invention is applied. FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus to which a cleaning device according to an embodiment of the present invention is applied. As an image forming apparatus 10 according to an embodiment of the present invention, an image forming process is performed based on image information transmitted from an external device such as a computer, and a so-called tandem image forming apparatus (color printer) 10 is provided. An example will be described.

  Here, a tandem image forming apparatus will be described as an example of the image forming apparatus. However, the image forming apparatus may be any image forming apparatus using an electrophotographic method, and is not limited to a tandem image forming apparatus. The type of image forming apparatus will be described by taking a color printer as an example, but it may be, for example, a copying machine, a facsimile machine, a multifunction machine, and the like, and is not limited to a color printer.

  As shown in FIG. 1, the image forming apparatus 10 includes a sheet feeding unit 12 that feeds a sheet P and is fed from the sheet feeding unit 12. While conveying the paper P, an image forming unit 13 that forms a toner image based on image information on the paper P, and an unfixed toner image formed on the paper P by the image forming unit 13 is fixed on the paper P. A fixing unit 14 for performing a fixing process is provided. Further, on the upper part of the apparatus main body 11, a paper discharge unit 15 for discharging the paper P subjected to the fixing process by the fixing unit 14 is formed.

  At an appropriate position on the upper surface of the apparatus main body 11, an unillustrated operation panel for inputting an output condition for the paper P is provided. This operation panel is provided with a power key and various keys for inputting output conditions.

  Further, a sheet conveyance path 111 extending in the vertical direction is formed in the apparatus main body 11 at a position on the right side of the image forming unit 13 shown in FIG. A pair of conveyance rollers 112 is provided at an appropriate position on the sheet conveyance path 111. The paper transport path 111 transports the paper P from the paper feed unit 12 to the paper discharge unit 15 by the transport roller pair 112, and the paper P being transported passes through the transfer unit and the fixing unit 14 of the image forming unit 13. It is formed to pass.

  The paper feed unit 12 includes a paper feed tray 121, a pickup roller 122, and a paper feed roller pair 123. The sheet feeding tray 121 is detachably mounted at a position below the image forming unit 13 in the apparatus main body 11 and stores a sheet bundle P1 in which a plurality of sheets P are stacked. The pickup roller 122 is provided at an upper position on the upstream side of the paper feed tray 121 in the conveyance direction of the paper P, specifically, at an upper right position shown in FIG. The top sheet P is taken out one by one. The paper feed roller pair 123 sends the paper P taken out by the pickup roller 122 to the paper transport path 111. By doing so, the paper feeding unit 12 feeds the paper P toward the image forming unit 13.

  The paper feed unit 12 further includes a manual feed tray 124, a pickup roller 125, and a paper feed roller pair 126 attached to the left side surface of the apparatus main body 11 shown in FIG. The manual feed tray 124 is for supplying the paper P toward the image forming unit 13 by manual feed operation. The manual feed tray 124 can be stored on the side surface of the apparatus main body 11, and when the paper P is manually fed, as shown in FIG. 1, the manual feed tray 124 is pulled out from the side surface of the apparatus main body 11 to be manually fed. The pickup roller 125 takes out the paper P placed on the manual feed tray 124. The paper P taken out by the pickup roller 125 is sent out to the paper transport path 111 by a pair of paper feed rollers 123 and 126. By doing so, the paper feeding unit 12 feeds the paper P toward the image forming unit 13.

  The image forming unit 13 forms an image such as a color image on the paper P fed from the paper feeding unit 12 by predetermined image processing. The image forming unit 13 includes a plurality of image forming units 131, an intermediate transfer belt (intermediate transfer member) 132, a primary transfer roller 133, and a secondary transfer roller 134.

  As the image forming unit 131, in this embodiment, the magenta (M) color is sequentially arranged from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 132 (from the left side to the right side in FIG. 1). A magenta unit 131M using a developer, a cyan unit 131C using a cyan (C) developer, a yellow unit 131Y using a yellow (Y) developer, and a black (K) developer are used. A black unit 131K is provided. Each unit 131 includes a photosensitive drum 135 as an image carrier, and forms a toner image corresponding to each color on the photosensitive drum 135 based on image information, and performs primary transfer onto the intermediate transfer belt 132.

  In the image forming unit 131, a photosensitive drum 135 as an image carrier is disposed at a central position so as to be rotatable in the direction of an arrow (clockwise in FIG. 1). Then, around the photosensitive drum 135, when the transfer (primary transfer) position by the primary transfer roller 133 is the most upstream side in the rotation direction of the photosensitive drum 135, the position is shifted from there to the downstream side. The neutralization device 24, the charging device 21, the exposure device 22, the development device 23, and the like are arranged in order so as to be a neutralization position, a charging position, an exposure position, and a development position, respectively. .

  The photosensitive drum 135 is for forming a toner image corresponding to each color on the peripheral surface based on image information. The charging device 21 is for charging the peripheral surface of the photosensitive drum 135 rotated in the direction of the arrow. The exposure device 22 irradiates the peripheral surface of the photosensitive drum 135 whose peripheral surface is charged by the charging device 21 with laser light based on image information, and electrostatically based on the image information on the peripheral surface of the photosensitive drum 135. This is for forming a latent image. Examples of the exposure device 22 include an LED head unit and a laser scanning unit (LSU). The developing device 23 is for developing the electrostatic latent image formed on the peripheral surface of the photosensitive drum 135 into a toner image.

  The intermediate transfer belt 132 is for transferring (primary transfer) a toner image based on image information to the peripheral surface (contact surface) of the plurality of image forming units 131. That is, in the present embodiment, the intermediate transfer belt 132 is an image carrier that is sandwiched between the photosensitive drum 135 and the primary transfer roller 133 and has a peripheral surface to which a toner image is transferred from the photosensitive drum 135. .

  The intermediate transfer belt 132 is an endless belt-like rotator, and is stretched around the driving roller 136 and the driven roller 137 so that the circumferential surface side thereof abuts on the circumferential surface of each photosensitive drum 135. ing. Further, the intermediate transfer belt 132 is pressed against each photoconductive drum 135 by each primary transfer roller 133 disposed at a position facing each photoconductive drum 135 via the intermediate transfer belt 132, and the driving roller 136. It is comprised so that it may rotate endlessly by rotational drive. The driving roller 136 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 132 endlessly. The driven roller 137 is rotatably provided and rotates following the endless rotation of the intermediate transfer belt 132 by the driving roller 136.

  Further, the intermediate transfer belt 132 is not particularly limited. Specifically, for example, the surface of a seamless belt made of resin such as polyimide, polycarbonate, and polyvinylidene fluoride, synthetic rubber such as silicone rubber and fluorine rubber, or urethane is used. Examples thereof include a belt formed of a coating layer (elastic layer) such as a resin. As an example of a preferable intermediate transfer belt 132, for example, an elastic layer containing a urethane resin is provided on a PVDF (polyvinylidene fluoride) underlayer, and a PTFE (polytetrafluoroethylene) coating layer is formed thereon. It is a belt made. In some cases, a conductive filler such as carbon black is added to the coating layer in order to impart conductivity.

  The primary transfer roller 133 is for primary transfer of the toner image formed on the photosensitive drum 135 to the intermediate transfer belt 132. That is, in the present embodiment, the primary transfer roller 133 is a transfer unit that sandwiches the intermediate transfer belt 132 and primarily transfers the toner image on the circumferential surface of the photosensitive drum 135 to the intermediate transfer belt 132.

  Further, the primary transfer roller 133 is disposed at a position facing each photosensitive drum 135 with the intermediate transfer belt 132 interposed therebetween. The primary transfer roller 133 is provided for each photosensitive drum 135 of each image forming unit 131. Further, as described above, the primary transfer roller 133 is in contact with the intermediate transfer belt 132 so that the intermediate transfer belt 132 is pressed against the photosensitive drum 135. In addition, the primary transfer roller 133 rotates depending on the endless rotation of the intermediate transfer belt 132 while being in contact with the intermediate transfer belt 132. At that time, by applying a primary transfer bias voltage having a polarity opposite to the charging polarity of the toner to each primary transfer roller 133, the toner image formed on each photoconductor drum 135 is changed to each photoconductor drum. Primary transfer is performed on the intermediate transfer belt 132 between the 135 and the corresponding primary transfer rollers 133. As a result, the toner images formed on the respective photosensitive drums 135 are sequentially primary-transferred sequentially in an overcoated state on the intermediate transfer belt 132 that rotates in the direction of the arrow (counterclockwise in FIG. 1).

  The secondary transfer roller 134 is for transferring (secondary transfer) the toner image on the intermediate transfer belt 132 onto the paper P fed from the paper feeding unit 12. That is, in the present embodiment, the secondary transfer roller 134 contacts the peripheral surface of the intermediate transfer belt 132 to form a nip portion, and the intermediate transfer belt 132 is formed on a sheet P that is a recording medium passing through the nip portion. 2 is a secondary transfer portion for secondary transfer of the toner image on the peripheral surface of the toner.

  The secondary transfer roller 134 is disposed at a position facing the drive roller 136 with the intermediate transfer belt 132 interposed therebetween. Further, the secondary transfer roller 134 is rotated in accordance with the endless rotation of the intermediate transfer belt 132 while being in contact with the intermediate transfer belt 132. At this time, a secondary transfer bias voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 134 so that the toner image primarily transferred onto the intermediate transfer belt 132 is transferred to the secondary transfer roller 132. Secondary transfer is performed between the sheet 134 and the driving roller 136 on the sheet P fed from the sheet feeding unit 12. As a result, the toner image based on the image information is transferred onto the paper P in an unfixed state.

  In addition, the image forming unit 13 further includes a cleaning device 200 at a position downstream of the secondary transfer position in the rotation direction from the secondary transfer position and upstream of the primary transfer position in the rotation direction. The cleaning device 200 is for removing and cleaning the toner (residual toner) remaining on the peripheral surface of the intermediate transfer belt 132 after the secondary transfer. The peripheral surface of the intermediate transfer belt 132 cleaned by the cleaning device 200 goes to the primary transfer position for a new primary transfer process. The residual toner (waste toner) removed by the cleaning device 200 is collected in a toner collection bottle (not shown) through a predetermined path and stored. The configuration of the cleaning device 200 will be described later.

  The fixing unit 14 performs a fixing process on the toner image on the paper P transferred by the image forming unit 13. The fixing unit 14 is stretched between a heating roller 141 including an energization heating element as a heating source therein, a fixing roller 142 oriented with the heating roller 141, and the fixing roller 142 and the heating roller 141. A fixing belt 143 and a pressure roller 144 disposed to face the fixing roller 142 with the fixing belt 143 interposed therebetween are provided.

  The paper P supplied to the fixing unit 14 is heated and pressed by passing through a fixing nip formed between the fixing belt 143 and the pressure roller 144. As a result, the toner image transferred to the paper P by the image forming unit 13 is fixed to the paper P. The sheet P that has been subjected to the fixing process is discharged toward the sheet discharge tray 151 of the sheet discharge unit 15 provided at the top of the apparatus main body 11 through the sheet conveyance path 111 extending from the upper part of the fixing unit 14. Paper.

  The paper discharge unit 15 is formed by recessing the top of the apparatus main body 11, and a paper discharge tray 151 for receiving the discharged paper P is formed at the bottom of the concave portion.

  Hereinafter, the cleaning device 200 will be described. FIG. 2 is a schematic cross-sectional view showing the configuration of the cleaning device 200 according to the embodiment of the present invention, and shows an enlarged peripheral portion of the cleaning device 200 provided in the image forming apparatus 10 shown in FIG. is there.

  The cleaning device 200 includes a removal roller 201, a collection roller 202, a blade 204, a discharge unit 205, a sheet 203, and the like.

  The removal roller 201 removes residual toner on the intermediate transfer belt 132 by rotating while contacting the surface of the intermediate transfer belt 132 that is an image carrier. At that time, during the secondary transfer, the paper is pressed against the intermediate transfer belt 132 by the secondary transfer roller 134, so that paper-derived foreign matters such as paper dust generated from the paper are also removed from the intermediate transfer belt 132. The

  The removal roller 201 is not particularly limited as long as it can remove residual toner and paper-derived foreign matter from the intermediate transfer belt 132. For example, a fur brush etc. are mentioned. By using a fur brush as the removal roller, it is possible to remove residual toner on the intermediate transfer belt 132 and foreign matters derived from the paper while suppressing damage to the intermediate transfer belt 132 as an image carrier. Moreover, as a fur brush, the brush etc. which made the fur brush shape etc. which wound the bundle which bundled the several filament yarn and made it pile shape are mentioned, for example. Moreover, as this fur brush, the fur brush which consists of an acrylic fiber (conductive acrylic fiber) provided with electroconductivity by adding electroconductive fillers, such as carbon black, is used preferably.

  Further, the removal roller 201 is provided such that the amount of biting, that is, the amount of biting of the removal roller 201 into the intermediate transfer belt 132 that is an image carrier, decreases as the image forming time increases. The intermediate transfer belt 132 is whitened as the image forming time increases, and the conveyance force of foreign matters derived from paper such as paper dust gradually decreases. The amount of foreign material derived from the paper gradually decreases. For this reason, even if the amount of biting by the removal roller 201 decreases as the image forming time increases, it is possible to suitably remove foreign matters derived from paper such as paper dust conveyed by the intermediate transfer belt 132. . Note that the amount of biting of the removal roller 201 is the distance from the position where the intermediate transfer belt 132 is in contact with the position where the intermediate transfer belt 132 is not present.

  Further, the method for reducing the amount of biting of the removal roller 201 is not particularly limited as long as it decreases as the image forming time increases. Specifically, a removal roller whose biting amount gradually decreases as the image formation time increases may be used, or the removal roller is gradually separated from the intermediate transfer belt 132 as the image formation time increases. It may be.

  Further, the biting amount of the removal roller 201 is preferably 1 mm or more, and more preferably 1 to 1.25 mm in an initial state before the start of image formation. If the amount of biting is too small, there is a tendency that foreign matters derived from paper such as paper dust conveyed from the intermediate transfer belt 132 cannot be suitably removed. Further, if the amount of biting is too large, there is a possibility that a step-out occurs due to an increase in torque applied to the removal roller 201 or the intermediate transfer belt 132, or a cleaning failure occurs due to wrinkling of the intermediate transfer belt 132. . In addition, the removal roller 201 and the intermediate transfer belt 132 tend to be damaged. Therefore, the amount of biting in the initial state of the removal roller 201 is within the above range, so that foreign matters derived from the paper such as paper dust are suitably removed while suppressing damage to the removal roller 201 and the intermediate transfer belt 132. it can.

  The biting amount of the removal roller 201 is preferably 0.75 mm or less, and more preferably 0.3 to 0.75 mm after image formation is performed for P30000 sheets of paper. If the amount of biting is too small, the amount of foreign matters derived from paper such as paper dust conveyed by the intermediate transfer belt 132 tends to decrease, but there is a tendency that it cannot be suitably removed. If the amount of biting is too large, the removal roller 201 is more than necessary for the intermediate transfer belt 132 even though the amount of foreign matters derived from paper such as paper dust conveyed by the intermediate transfer belt 132 is reduced. It will be a strong hit. For this reason, damage to the removal roller 201 and the intermediate transfer belt 132 tends to increase. Therefore, the amount of biting after the image formation of the removal roller 201 for a predetermined time is within the above range, and therefore the amount of biting according to the transport amount of foreign matters derived from paper such as paper dust, While suppressing damage to the roller 201 and the intermediate transfer belt 132, foreign matters derived from paper such as paper dust can be suitably removed. Note that the image forming time increases as the number of images to be formed increases. Here, the predetermined time is a time required to form an image for P30000 sheets of paper.

  Further, in the cleaning device according to the present embodiment, even if the amount of biting of the removal roller 201 decreases from 1 mm to 0.75 mm with an increase in image formation time, the surface of the recovery roller 202 The cleaning performance can be maintained by reducing the roughness as follows.

  The collection roller 202 collects the toner and foreign matter removed by the removal roller 201 by rotating while contacting the surface of the removal roller 201. The collection roller 202 is not particularly limited as long as it can collect residual toner and paper-derived foreign matter from the removal roller 201. Specifically, a metal roller having a voltage application unit that applies a voltage to the metal roller can be used. Moreover, as an example of a preferable metal roller, for example, a roller formed by subjecting a roller surface made of sulfur and sulfur composite free-cutting steel (SUM) material to blasting and further applying nickel (Ni). By applying a voltage to the metal roller, residual toner and paper-derived foreign matter can be collected from the removal roller 201. This is because the residual toner is considered to be charged, for example, positively charged. Then, it is considered that the toner is adsorbed by applying a voltage so that the metal roller is charged with a polarity opposite to that of the toner. At that time, it is considered that the paper powder is weaker than the toner and is attracted to the collection roller, but the paper powder is also collected by the collection roller.

  The collection roller 202 is provided so that its surface roughness decreases as the image formation time increases. As described above, the conveyance amount of foreign matters derived from paper such as paper dust by the intermediate transfer belt 132 decreases as the image forming time increases. For this reason, the amount of foreign matter derived from paper such as paper dust removed from the intermediate transfer belt 132 by the removal roller 201 also decreases as the image forming time increases. For this reason, it is preferable that the surface roughness of the collection roller 202 is reduced in accordance with a reduction in the amount of foreign matters derived from paper such as paper dust removed by the removal roller 201. In addition, when the surface roughness of the collection roller 202 is large, the conveying force of foreign matters derived from paper such as paper dust increases, while blade damage increases. By reducing the surface roughness of the collection roller 202 in this way, the surface roughness corresponding to the necessary conveying force is obtained. Therefore, damage to the blade can be suppressed while appropriately collecting foreign matters derived from paper such as paper dust removed by the removal roller 201.

  Further, the method for reducing the surface roughness of the collection roller 202 is not particularly limited as long as it is reduced as the image forming time increases. Specifically, a recovery roller whose surface roughness gradually decreases as the image formation time increases may be used. A blade that contacts the collection roller may be one that gradually decreases the surface roughness of the collection roller as the image forming time increases. In addition, the blade may be installed so that the linear pressure or the cleaning angle of the blade with respect to the collection roller gradually decreases the surface roughness of the collection roller.

  Further, the ten-point average roughness Rz of the surface of the collection roller 20 is preferably 3 to 6 μm, and more preferably 3.5 to 5 μm in an initial state before the start of image formation. If the ten-point average roughness Rz is too small, there is a tendency that it is not possible to suitably ensure the conveying force of foreign matters such as toner and paper dust. Further, if the ten-point average roughness Rz is too large, blade damage tends not to be suitably suppressed. Further, the surface roughness of the recovery roller 202 is preferably an average interval Sm of irregularities of 50 to 150 μm, and more preferably 70 to 110 μm. If the average interval Sm of the unevenness is too small, there is a tendency that damage to the blade cannot be suitably suppressed. Further, if the average interval Sm of the irregularities is too large, there is a tendency that it is not possible to suitably secure the conveying force of foreign matters such as toner and paper dust. Therefore, if the surface roughness of the collection roller 202 is within the above range, the collection roller 202 can suitably transport the residual toner and the foreign matter.

  Further, the ten-point average roughness Rz of the surface of the collection roller 202 is preferably less than 3 μm and more preferably 1.5 μm or more and less than 3 μm after image formation is performed for P30000 sheets of paper. preferable. If the ten-point average roughness Rz is too small, the amount of foreign matter derived from paper such as paper dust that is removed by the removal roller 201 tends to be reduced, but the recovery roller 202 tends not to be suitably recovered. If the ten-point average roughness Rz is too large, the blade 204 is damaged more than necessary even though the amount of foreign matter derived from paper such as paper dust removed by the removing roller 201 is reduced. The surface roughness will be moderate. Therefore, the 10-point average roughness Rz after the image formation for a predetermined time of the collection roller 202 is within the above range, and thus the roughness according to the amount of foreign matters derived from paper such as paper dust. Thus, foreign matters derived from paper such as paper dust can be suitably collected while suppressing damage to the blade 204.

  That is, the ten-point average roughness Rz of the collection roller 202 is preferably decreased from 3 to 6 μm to 1.5 μm or more and less than 3 μm as the image forming time increases.

  In addition, the ten-point average roughness Rz and the average interval Sm of unevenness are values measured by a method based on JIS B 0601: 1994. For example, the surface roughness can be measured using a surface roughness measuring machine, specifically, Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd.

  The blade 204 comes into contact with the surface of the collection roller 202 and separates toner and foreign matter collected by the collection roller 202 from the collection roller 202. The separated toner and paper dust move to the discharge unit 205 positioned in the lower direction of the blade 204.

  The blade 204 is not particularly limited as long as it can separate toner and foreign matter from the collection roller 202. For example, a resin-made plate-like member can be used, and a plate-like member made of polyurethane rubber can be used. One end of the plate member is in contact with the surface of the collection roller 202. The plate-like member is in contact so that the direction from the other end toward the end in contact with the surface of the collection roller 202 is opposite to the rotation direction of the collection roller 200. ing. By doing so, the toner and foreign matter collected by the collection roller 202 are separated from the collection roller 202 so as to be scraped by the blade 204.

  The blade has an impact resilience of 45 ° or more, more preferably 45 to 80 °, and further preferably 45 to 60 ° in terms of international rubber hardness. If the rebound resilience is too small, there is a tendency that residual toner and foreign matter cannot be suitably separated from the collection roller by the blade. That is, slipping from the blade tends to occur. Moreover, there exists a tendency which cannot reduce the surface roughness of a collection roller suitably. Further, if the impact resilience is too large, the surface roughness of the recovery rotor tends to be reduced too much.

  The international rubber hardness can be measured, for example, by a method based on JIS K 6253, N method or H method, using a prescribed test piece (8 mm thick upper and lower surfaces are planar shapes).

  When the blade 204 is provided so as to come into contact with the collection roller 202, the blade 204 is in a state as shown in FIG. First, when the blade 204a without the collection roller comes into contact with the collection roller 202, the tip of the blade moves. Then, the tip of the blade 204b in that state actually bends. When the blade 204 is provided so as to come into contact with the collection roller 202, the blade 204c is in a state as shown in FIG. The cleaning angle is an angle θ1 formed by the tangent line at the tip of the blade 204 and the tangent line in contact with the blade of the collection roller 202. FIG. 4 is a diagram for explaining the state of the blade.

  Further, the linear pressure of the blade 204 against the collection roller 202 is preferably 12 gf / cm or more, and more preferably 12 to 25 gf / cm. If this linear pressure is too small, there is a tendency that residual toner and foreign matter cannot be suitably separated from the collection roller by the blade. That is, slipping from the blade tends to occur. Moreover, there exists a tendency which cannot reduce the surface roughness of a collection roller suitably. Further, if the linear pressure is too large, the blade damage tends not to be sufficiently suppressed.

  The cleaning angle of the blade 204 is preferably 12 ° or more, more preferably 12 to 30 °, and still more preferably 15 to 20 °. If the cleaning angle is too small, there is a tendency that residual toner and foreign matters cannot be suitably separated from the collection roller by the blade. That is, slipping from the blade tends to occur. Moreover, there exists a tendency which cannot reduce the surface roughness of a collection roller suitably. If the cleaning angle is too large, blade damage tends not to be sufficiently suppressed.

  The linear pressure and the cleaning angle can be adjusted according to the type of blade and the amount of biting of the blade. As shown in FIG. 4, the amount of biting of the blade is the distance y between the position in contact with the collection roller 202 and the position when there is no collection roller.

  The discharge unit 205 discharges the toner and foreign matter separated from the collection roller 202 from the cleaning device 200. The discharge unit 205 includes, for example, a discharge roller in parallel with the collection roller 202 and the like, and the rotation of the discharge roller removes toner and foreign matter in a direction in which the discharge roller extends (perpendicular to the paper surface in FIG. 2). And the like and the like discharged from the cleaning device 200. The waste toner removed by the cleaning device 200 is collected in a toner collection bottle (not shown) through a predetermined path and stored.

  The sheet 203 is disposed between the removal roller 201 and the discharge unit 205, and one end thereof is brought into contact with the surface of the collection roller 202. The sheet 203 is in contact so that the direction from the other end toward the end in contact with the surface of the collection roller 202 is the same as the rotation direction of the collection roller 200. That is, it is installed so as to face the blade 204, and the sheet 203 and the blade 204 partition the removal roller 201 side and the discharge unit 205 side. Further, the other end of the sheet 203 is connected to, for example, a housing of the cleaning device 200 so that the removal roller 201 side and the discharge unit 205 side can be partitioned.

  Without such a sheet 203, the toner and foreign matter separated from the collection roller 202 by the blade 203 are left to free fall, so that not only the discharge unit 205 located below the blade 204 but also the removal is removed. It is thought that it will also transfer to the roller 201 side. That is, it is considered that the residual toner removed from the intermediate transfer belt 132 by the cleaning device 200 returns not only to the discharge unit 205 but also to the intermediate transfer belt 132 that is an image carrier. For this reason, the sheet 203 can suppress toner scattering from the cleaning device.

  As the sheet 203, a sheet including a base material 206 and a layer (powder layer) 207 made of powder arranged in at least a region of the base material 206 in contact with the recovery roller 202 is used. preferable. FIG. 2 shows a case where a layer 207 made of powder is provided on the entire surface of the substrate 206 on the side in contact with the collection roller 202. The powder layer 207 should just be arrange | positioned in the area | region which contacts the collection roller 202 among the surfaces on the side which contacts the collection roller 202 of the base material 206. FIG.

  Further, when a sheet that does not include powder as a conventional sheet is used as the sheet, as described above, the toner separated from the collection roller by the blade may leak to the image carrier side. This is considered to be because a gap is formed between the sheet and the collection roller when foreign matters such as paper dust enter between the sheet and the collection roller. On the other hand, by using the sheet 203 as described above so that the powder layer 207 is in contact with the collection roller 202, the toner and foreign matter separated from the collection roller 202 can be separated from the sheet 203 and the collection roller 202. The residual toner removed from the image carrier can be prevented from leaking to the image carrier side.

  Further, the powder layer 207 is not particularly limited as long as the powder layer 207 can be disposed on the sheet 203 to reduce adhesion of foreign matters such as paper dust to the sheet 203. Examples of the powder of the powder layer 207 include a toner for forming a toner image on an image carrier and particles contained in the toner. Examples of the particles contained in the toner include particles such as titanium oxide and zinc stearate. With such a powder, the adhesion of foreign matters such as paper dust to the sheet 203 can be reduced, and even if the powder is detached from the substrate 206 and adhered to the image carrier or the like, an image to be formed is formed. Has little effect on image quality.

  The particle diameter of the powder is preferably a volume average particle diameter and smaller than the ten-point average roughness Rz of the surface of the substrate. Specifically, the particle diameter of the powder is preferably a volume average particle diameter of 200 nm to 1 μm, and more preferably 200 to 400 μm. In the present embodiment, the base material has a surface roughness of 10 to 10 μm with a 10-point average roughness Rz. Thus, when the particle diameter of the powder is small, it is considered that the powder appropriately enters the irregularities of the base material of the sheet, and a layer made of the powder can be suitably formed on the base material. . In the sheet thus obtained, since a layer made of powder is suitably formed, the adhesion force of foreign matters derived from the paper, for example, paper powder, can be more suitably reduced. Therefore, leakage of residual toner removed from the image carrier to the image carrier side can be further suppressed.

  The volume average particle size can be calculated from a particle size distribution measured by a known method such as a dynamic light scattering method. For example, it can be measured by a particle size meter (Multisizer 3 manufactured by Beckman Coulter, Inc.).

  Further, the base material 206 is not particularly limited as long as the toner and foreign matter conveyed by the collection roller 202 can pass between the sheet 203 and the collection roller 202. Specifically, the Young's modulus of the substrate 206 is preferably 100 MPa or less. For example, a polyethylene terephthalate (PET) sheet has a Young's modulus exceeding 100 MPa, and when this sheet is used as a sheet, the toner and foreign matter conveyed by the collection roller can suitably pass between the sheet and the collection roller. Disappear. Therefore, when a polyethylene terephthalate (PET) sheet is used as a base material, it is not a sheet in this embodiment. The Young's modulus of the substrate 206 is preferably 45 MPa or more. Therefore, the Young's modulus of the substrate 206 is preferably 45 to 100 MPa. If the Young's modulus of the substrate 206 is too high, there is a tendency that the toner and foreign matter conveyed by the collection roller 202 cannot pass between the sheet 203 and the collection roller 202 suitably. If the Young's modulus of the substrate 206 is too low, the sheet 203 is too soft and the contact state between the sheet 203 and the collection roller 202 tends not to be suitably maintained. The substrate 206 is preferably a thermoplastic polyurethane sheet.

  The method for forming the powder layer 207 is not particularly limited as long as the powder layer 207 can be formed at a predetermined location on the substrate 206. Specifically, it can be formed by coating the powder on the substrate 206.

  Moreover, it is preferable that the position of one edge part of the said sheet | seat 203 is arrange | positioned in the position which is 0.2-1 mm in distance with the position when the said collection | recovery roller 202 does not exist. That is, the amount of biting of the sheet 203 is preferably 0.2 to 1 mm, and more preferably 0.5 to 0.8 mm. If the amount of biting is too small, there is a tendency that the residual toner removed from the image carrier cannot be sufficiently prevented from leaking to the image carrier side. If the amount of biting is too large, the toner and foreign matter conveyed by the collection roller 202 tend not to pass between the sheet 203 and the collection roller 202 in a suitable manner. Therefore, if the amount of biting of the sheet 203 is within the above range, not only can the residual toner removed from the image carrier be prevented from leaking out to the image carrier side, but also between the sheet and the collection roller. The residual toner and the foreign matter can be suitably passed through.

  By using the sheet 203 as described above so that the powder layer 207 is in contact with the recovery roller 202, leakage of residual toner removed from the image carrier to the image carrier side can be sufficiently suppressed. .

  Further, the cleaning device can maintain excellent cleaning performance for a long period of time. This is considered to be due to the following.

  As described above, the cleaning device is a cleaning device that sufficiently suppresses leakage of residual toner removed from the image carrier to the image carrier side. Then, foreign matters such as paper dust conveyed from the image carrier gradually decrease when the image formation is performed over a long period of time because the conveyance force of the image carrier gradually decreases. From this, it is possible to suitably remove foreign matters such as paper dust from the image carrier even if the amount of the removal roller biting into the image carrier is gradually reduced as the image formation time increases. . In addition, the recovery roller having a conveyance force that can sufficiently suppress leakage of residual toner to the image carrier side so as to achieve excellent cleaning performance may damage the blade. In contrast, since the amount of residual toner removed by the removal roller decreases as the image formation time increases, the amount of residual toner remaining on the image carrier side even if the surface roughness of the collection roller is gradually reduced. It is considered that toner leakage can be sufficiently suppressed. As the image forming time increases, the surface roughness of the collection roller is gradually reduced, so that it is considered that damage to the blade is also suppressed. For this reason, it is considered that the removal of residual toner by the blade from the collection roller is also preferably performed over a long period of time. Therefore, it is considered that, according to the above configuration, excellent cleaning performance can be maintained over a long period of time.

  Therefore, the image forming apparatus including the cleaning device as described above can form a high-quality image over a long period of time. This is considered to be because image quality deterioration due to the presence of residual toner or paper-derived foreign matter can be suitably suppressed over a long period of time.

  In the above-described image forming apparatus, the cleaning device according to the present embodiment transfers the toner image developed by the developing device and transfers the transferred toner image onto a sheet. It is provided for removing residual toner and foreign matters on the transfer belt, that is, provided as a belt cleaning device. The cleaning device according to the present embodiment is not limited to use as such a belt cleaning device, and can be used for removing toner. For example, as shown in FIG. 3, a photosensitive member that forms a toner image developed by a developing device on its surface, specifically, used to remove residual toner and foreign matter on the photosensitive drum. it can. That is, it can be used as a cleaning device for cleaning the photoreceptor, such as a drum cleaning device. Therefore, the cleaning device according to the present embodiment can be used as a belt cleaning device or a cleaning device for cleaning a photoreceptor such as a drum cleaning device.

  Hereinafter, a case where the cleaning device according to the present embodiment is used as a drum cleaning device will be described.

  FIG. 3 is a schematic diagram showing the periphery of the image forming unit of the image forming apparatus 300 to which the cleaning device according to the embodiment of the present invention is applied. The image forming apparatus 300 is an apparatus that forms a predetermined image on a sheet 330 that is a recording medium by an electrophotographic method. Further, as shown in FIG. 3, the image forming apparatus 300 is arranged around a photosensitive drum 331 that is an image carrier in order along the rotation direction A of the photosensitive drum 331, in order, a charging device 332, an exposure device 333, and a developing device. A device 334, a transfer roller 336, a cleaning device 200, a static eliminator 338, and the like are provided. Note that the cleaning device 200 and the static eliminator 338 may be reversed.

  In the present embodiment, the photosensitive drum 331 is described by taking a photosensitive drum as a drum-shaped photosensitive member as an example. However, the photosensitive drum 331 is not limited thereto, and is not limited to this, and a belt-shaped photosensitive member and a sheet-shaped photosensitive member. It can also be applied to the body. The charging device 332 charges the surface of the photosensitive drum 331. The exposure device 333 forms an electrostatic latent image by selectively attenuating the surface potential of the photosensitive drum 331 by irradiating light based on image data. The developing device 334 forms a toner image by developing the electrostatic latent image formed on the surface of the photosensitive drum 331 with toner. The transfer roller 336 transfers the toner image formed on the photosensitive drum 331 onto the paper 330. The cleaning device 200 is a device for removing toner remaining on the surface of the photosensitive drum 331. The cleaning device 200 is the same as the cleaning device except that the removal roller 201 provided is changed from the intermediate transfer belt to the photosensitive drum. The neutralization device 338 neutralizes the surface charge of the photosensitive drum 331 with lamp light.

  Further, the image forming apparatus 300 includes a fixing device 341 (a heating roller 342 and a pressure roller 343) on the downstream side in the conveyance direction of the paper 330. The fixing device 341 applies heat and pressure to the paper 330 on which the toner image is transferred to fix the toner image, thereby forming a predetermined image on the paper 330. According to such an image forming apparatus, a high-quality image can be formed. This is presumably because the residual toner removed by the cleaning device is preferably suppressed from returning to the photoconductor, and the photoconductor drum is preferably cleaned.

  First, the sheet was examined.

(Sheet 1)
On the surface of a thermoplastic polyurethane sheet (t0.1 made by Seadam Co., Ltd., Young's modulus 45 MPa, PET sheet (PET # 125), surface roughness: 10-point average roughness Rz 10 μm), titanium oxide (volume average particle diameter) 250 nm). By doing so, the sheet | seat (sheet | seat 1) provided with the powder layer was obtained.

(Sheet 2)
The same as Example 1 except that zinc stearate (volume average particle diameter 6 μm) was used instead of titanium oxide. By doing so, the sheet | seat (sheet | seat 2) provided with the powder layer was obtained.

(Sheet 3)
The same as Example 1 except that titanium oxide is not used. That is, it is a thermoplastic polyurethane sheet (sheet 3).

(Evaluation)
The paper dust adhesion of these sheets was measured. Specifically, paper powder was adhered on each sheet, and the force [F50 (nN)] when the amount of the adhered paper powder was halved was measured using a centrifuge. The result is shown in FIG. FIG. 5 is a graph showing the result of the paper dust adhesion of the sheet.

  From this result, it can be seen that in the case of the sheets (sheet 1 and sheet 2) provided with the powder layer, the paper powder adhesion force is significantly lower than that of the sheet (sheet 3) not provided with the powder layer.

  In addition, a polyethylene terephthalate (PET) sheet that cannot be used as a sheet in the present invention, that is, foreign matter cannot pass between the sheet and the collection roller (Sheet 4: Lumirror made by Toray Industries, Young's modulus 45 GPa) Even in this case, if the powder layer is not provided, it can be seen that the paper powder adhesion is higher than that of the sheets 1 and 2.

  In addition, the sheet was examined using an image forming apparatus (Ecosys P6040 manufactured by Kyocera Document Solutions Co., Ltd.) as shown in FIG. Further, as an intermediate transfer belt, an elastic belt (manufactured by Okura Kogyo Co., Ltd., provided with an elastic layer containing urethane resin on a base layer of PVDF (polyvinylidene fluoride), and PTFE (polytetrafluoroethylene) is provided thereon. A belt formed with a coating layer of the above was used. Further, as the removing roller, a fur brush (SA-7 manufactured by Toei Sangyo Co., Ltd., a fur brush made of acrylic fiber (conductive acrylic fiber) provided with conductivity) was used. As a recovery roller, a roller (surface roughness: ten-point average roughness Rz4.) Obtained by subjecting a roller made of sulfur and sulfur composite free-cutting steel (SUM) material to blasting and further applying nickel (Ni). 5 μm and the average interval Sm of 80 μm). As the blade, a polyurethane rubber cleaning blade (1577E manufactured by Bando Chemical Co., Ltd., rebound resilience (international rubber hardness) 47 °, rubber hardness A77, Young's modulus 9.5 MPa, thickness 1.4 mm) was used. The bias value applied to the collection roller was −3 μA. The sheet 1 was used as the sheet.

  At this time, the linear pressure of the blade against the collection roller and the cleaning angle of the blade were examined. Images were formed at various linear pressures and cleaning angles. At that time, toner blade slippage was evaluated. When the toner can be suitably removed from the collecting roller, it is evaluated as “◯”, and when it is determined that the toner is slightly slipped, it is evaluated as “△”, and it is determined that the toner is slipped through. In the case, it was evaluated as “×”. The results are shown in Table 1.

  Also, as the blade, a polyurethane rubber cleaning blade (Hokkaido Industrial Co., Ltd., 238707, rebound resilience (international rubber hardness) 40 °, rubber hardness A70, Young's modulus 6.6 MPa, thickness 1.6 mm) is used. The blade slip was evaluated in the same manner as described above. The results are shown in Table 2.

  From Tables 1 and 2, by providing a blade with a rebound resilience of 45 ° or more so as to have a linear pressure of 12 gf / cm or more and a cleaning angle of 12 ° or more, blade slipping can be suitably suppressed.

  As the blade, for example, a polyurethane rubber cleaning blade (1577E manufactured by Bando Chemical Co., Ltd.) is used so that the linear pressure is 12 gf / cm or more and the cleaning angle is 12 ° or more, for example, a linear pressure of 12.6 gf / cm, The cleaning angle was set to 13.4 °. When the image forming apparatus thus provided performs image formation for P30000 sheets of paper (performs the time required to perform image formation for 30000 sheets of paper), the ten-point average roughness Rz4.5 μm of the surface of the collection roller is It gradually decreased to 1.5 μm, which is less than 3 mm. The fur brush bite amount gradually decreased from 1.25 mm, which is 1 mm or more, to 0.75 mm when image formation was performed for P30000 sheets of paper.

  Even when image formation was performed for a long period of time using such an image forming apparatus, the amount of paper dust accumulated inside the removal roller side of the sheet in the cleaning device was small. This is considered to indicate that accumulation of paper dust on the downstream side of the collection roller of the sheet is suitably suppressed over a long period of time. From this, it was found that such an image forming apparatus can form high-quality images over a long period of time.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 132 Intermediate transfer belt (image carrier)
200 Cleaning Device 201 Removal Roller 202 Recovery Roller 203 Sheet 204 Blade 205 Discharge Portion 206 Substrate 207 Powder Layer

Claims (10)

A cleaning device provided in an image forming apparatus,
The residual toner remaining on the image carrier after the toner image on the image carrier is transferred to the paper and the foreign matters derived from the paper are brought into contact with the surface of the image carrier provided in the image forming apparatus. A removal roller for removal from the image carrier;
A collection roller that contacts the surface of the removal roller and collects residual toner and foreign matter removed by the removal roller;
A blade that contacts the surface of the collection roller and separates residual toner and foreign matter collected by the collection roller from the collection roller;
A discharge unit for discharging residual toner and foreign matter separated from the recovery roller;
A sheet disposed between the removal roller and the discharge unit, and having one end in contact with the surface of the collection roller;
An amount of the removal roller that bites into the image carrier and a surface roughness of the recovery roller are reduced with an increase in image formation time.   The cleaning device according to claim 1, wherein the surface roughness of the collection roller is reduced from 3 to 6 μm to 1.5 μm or more and less than 3 μm in terms of 10-point average roughness. The rebound resilience of the blade is 45 ° or more in international rubber hardness,
The cleaning device according to claim 1, wherein the blade has a linear pressure with respect to the collection roller of 12 gf / cm or more and a cleaning angle of 12 ° or more.   The position of the removal roller that is in contact with the image carrier is lowered from 1 mm to 0.75 mm in distance from the position when the image carrier is not present. 2. The cleaning device according to item 1.   The cleaning device according to any one of claims 1 to 4, wherein an average interval of the unevenness of the recovery roller is 50 to 150 µm.   The cleaning device according to claim 1, wherein the sheet includes a base material and powder disposed in an area of the base material that contacts at least the recovery roller.   The cleaning apparatus according to claim 6, wherein the base material is a thermoplastic polyurethane sheet.   The cleaning device according to claim 1, wherein the removing roller is a fur brush.   The cleaning device according to claim 1, wherein the image carrier is an intermediate transfer member to which a toner image developed by a developing device is transferred, and the transferred toner image is transferred to a sheet.   An image forming apparatus comprising the cleaning device according to claim 1.

Images