JP2007171822A - Cleaning device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device capable of effectively cleaning untransferred toner on an image carrier and post-transfer remaining toner in accordance with the charging characteristic of toner while achieving miniaturization and long life, and to inexpensively provide an image forming apparatus using the cleaning device by simple constitution. <P>SOLUTION: The cleaning device is provided with an image carrier 9, an untransferred toner collecting brush member BI freely rotatably formed in contact with the peripheral surface of the image carrier 9 and capable of cleaning an untransferred toner image formed on a non-image forming area and a post-transfer remaining toner collecting brush member BT freely rotatably formed in contact with the peripheral surface of the image carrier 9 adjacently to the untransferred toner collecting brush member BI and capable of cleaning post-transfer remaining toner in an image forming area. Toner accumulated in the untransferred toner collecting brush member BI is electrostatically collected and removed and toner accumulated in the post-transfer remaining toner collecting brush member BT is collected and removed by sucking the toner through a filter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine to which an electrophotographic system is applied, and in particular, a toner formed on an image carrier such as an intermediate transfer member. The present invention relates to a cleaning device for cleaning an image and an image forming apparatus using the same.

JP 07-191484 A

  2. Description of the Related Art Conventionally, an image forming apparatus using a belt-like member as a component is known. In this type of image forming apparatus, for example, a photosensitive drum composed of a rotationally driven rotating body, and a charging unit, a writing unit, a developing unit, a primary transfer unit, a cleaning unit, and the like disposed around the photosensitive drum are provided. And an intermediate transfer belt, which is a belt-like image carrier that is opposed to the photosensitive drum and rotates at the same peripheral speed as that of the photosensitive drum. In such an image forming apparatus, the intermediate transfer belt is rotationally driven in a predetermined direction, and a normal toner image is formed in the image forming area and a non-image forming area (hereinafter also referred to as an inter image). A mark image (hereinafter also referred to as an untransferred toner image) such as a patch for detecting the position of the intermediate transfer belt and the image density is formed.

  The toner image formed in the image forming area of the intermediate transfer belt is then transferred to a recording medium, and the transfer residual toner that has not been transferred and image toner such as patches formed in the inter image (hereinafter referred to as untransferred toner). The toner is also collected and removed by a cleaner.

  An electrostatic brush cleaner (ESB) cleaning device is known as such a cleaner (see, for example, Patent Document 1). In this electrostatic brush cleaner system, voltages having opposite polarities are applied to two brushes, for example, negatively charged toner is collected by a brush charged on the positive electrode side, and positive charge is collected by a brush charged on the negative electrode side. The toner is collected. Furthermore, there are known a method in which toner collected on a brush is electrostatically collected by a detoning roll (electrostatic roll) and a method in which air is sucked and collected from a brush.

  Here, in Patent Document 1, in the electrostatic brush cleaner system, voltages having opposite polarities are applied to two brushes arranged so as to contact the image carrier, and the positive electrode or the negative electrode after passing through the transfer nip. A system is disclosed in which toner on an image bearing member charged in an electrostatic manner is electrostatically collected, and the collected toner is collectively sucked by air.

  In general, an image forming toner image and an inter-image toner image for registration correction and toner density adjustment are formed on an image carrier such as a photosensitive belt or an intermediate transfer belt. Hereinafter, for the toner on the image carrier after passing through the transfer nip, the former is called untransferred toner and the latter is called untransferred toner.

  The transfer residual toner contains a large amount of low tribo toner (low charge toner) because electric charge is injected from the conductive external additive into the toner by discharge during transfer. When the toner is used, it is difficult to electrostatically collect these low-charged toners. Therefore, in the method using the conventional detoning roll, the low tribo toner is accumulated in the brush, but in such a method, when the allowable accumulation toner amount of the brush is exceeded, the low tribo toner is discharged from the brush, There was a problem that cleaning failure occurred.

  On the other hand, in the method of sucking with air as started in Patent Document 1, since the two brushes are sucked by one sucking device, there is a problem that the device becomes large. Further, the amount of untransferred toner for color registration adjustment and toner density adjustment is larger than the residual transfer toner (approximately 10 times the residual transfer toner), and if these toners are sucked at the same time, one suction is performed. As a result, the amount of toner accumulated in the filter increases, and the life of the cleaner is shortened.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and realizes a reduction in size and an extension of the life, and an untransferred toner on the image carrier according to the charging characteristics of the toner. Another object of the present invention is to provide a cleaning device capable of satisfactorily cleaning the transfer residual toner and an image forming apparatus using the same with a simple configuration at low cost.

  In order to achieve the above object, the cleaning device of the present invention forms a toner image to be transferred to a recording medium in a predetermined image forming area on the surface and forms an untransferred toner image in a non-image forming area. A rotatable image bearing member; a non-transferred toner collecting brush member that is rotatably formed in contact with the peripheral surface of the image bearing member; and that is adjacent to the untransferred toner collecting brush A transfer residual toner recovery brush member that is rotatably formed in contact with the peripheral surface of the image carrier and that cleans the transfer residual toner in the image forming region. The accumulated toner is electrostatically recovered and removed, and the toner accumulated on the transfer residual toner recovery brush member is recovered and removed by suction through a filter. It is an butterfly.

  Here, the untransferred toner is not only a toner that is formed in a non-image forming area and is not scheduled to be transferred to a recording medium, but is also unaffected by a transfer electric field and has an image bearing state without changing its charging characteristics. Toner remaining on the body (for example, toner jammed or shut down before the toner on the image carrier enters the transfer area, and remains on the image carrier without being affected by the transfer electric field). Shall be.

  In addition, the transfer residual toner refers to toner that remains on the image carrier in a state in which the charging characteristics are changed under the influence of the transfer electric field.

  In general, a mark image such as a patch formed in a non-image forming region (hereinafter also referred to as an inter image) of an image carrier for positional deviation adjustment and density adjustment is not transferred to a recording medium, and therefore is affected by a transfer electric field. Since the charge distribution of the toner hardly changes without receiving the electrostatic charge, electrostatic recovery is possible.

  On the other hand, since an electric field is applied to the toner image formed in the image forming area, electric charge is injected into the remaining toner that has not been transferred to the recording medium, and its polarity is reversed or low tribo is generated. (Low charge) state.

  The amount of toner remaining after transfer is small compared to the amount of toner (hereinafter also referred to as untransferred toner) formed in the interimage. Therefore, electrostatic recovery is difficult.

  Therefore, the cleaning device of the present invention configured as described above includes an image carrier, a recovery brush member for untransferred toner, and a recovery brush member for untransferred toner, and adheres to the recovery brush member for untransferred toner. The accumulated toner is electrostatically collected and removed, and the toner adhered and accumulated on the collection brush member for transfer residual toner is collected and removed by suction through a filter. By using the recovery brush for electrostatic recovery, and for the transfer residual toner, by performing suction recovery with the transfer residual toner recovery brush, it is possible to effectively realize recovery cleaning according to the charging characteristics of each toner. In addition, the filter can be prevented from clogging by separating and collecting untransferred toner and untransferred toner, thereby reducing the size and length of the device It is possible to realize a service life.

  Further, the untransferred toner collection brush member and the untransferred toner collection brush member are partitioned from each other by a partition plate, and the partition plate has a plurality of through holes formed therein. A one-way air flow path from the transfer toner recovery brush member to the transfer residual toner recovery brush member may be formed.

  In such a configuration, the untransferred toner collection brush member and the untransferred toner collection brush member are separated from each other by the partition plate, and a plurality of through holes are formed in the partition plate. Since a one-way air flow path from the untransferred toner recovery brush member to the untransferred toner recovery brush member is formed, a large amount of untransferred toner adhered and accumulated on the untransferred toner recovery brush member The partition plate prevents collection by suction and prevents clogging of the filter, and the cloud toner around the untransferred toner collection brush member is separated from the untransferred toner collection brush member through a plurality of through holes. The transfer residual toner can be reliably sucked and collected together with the transfer residual toner by the one-way air flow path toward the transfer residual toner recovery brush member.

  In addition, only the toner in a low charged state among the toner adhered and accumulated on the transfer residual toner collecting brush member may be collected and removed by suction.

  In such a configuration, only the low-charged toner is collected and removed by suction among the toner accumulated on the transfer residual toner collecting brush member, so that the amount of toner passing through the filter can be further reduced. Accordingly, the life of the cleaning device can be further extended.

  Furthermore, the untransferred toner recovery brush member may be arranged upstream of the untransferred toner recovery brush member along the rotation direction of the image carrier.

  In such a configuration, the untransferred toner recovery brush member is disposed on the upstream side of the transfer residual toner recovery brush member along the rotation direction of the image carrier. A large amount of untransferred toner is first recovered by the upstream untransferred toner recovery brush member, and the untransferred toner that has not been recovered can be sucked and recovered together with the residual transfer toner on the downstream side. Better cleaning of the body can be performed.

  Furthermore, the recovery brush member for untransferred toner and the recovery brush member for untransferred toner may be configured to be able to apply a cleaning voltage.

  In such a configuration, the recovery brush member for the untransferred toner and the recovery brush member for the transfer residual toner are configured to be able to apply a cleaning voltage, so that the electrostatic recovery cleaning according to the polarity of the toner is performed. Can be easily realized.

  Further, the untransferred toner collecting brush member has a conductive roll formed in contact with the brush member so as to be rotatable and mechanically removes toner on the roll surface in contact with the roll. A scraper may be further provided.

  In such a configuration, the untransferred toner collecting brush member includes a conductive roll formed in contact with the brush member and rotatable, and a toner on the roll surface in contact with the roll. And a scraper for mechanically removing the toner, the untransferred toner adhering to the untransferred toner collecting brush member is electrostatically moved to a conductive roll, and then mechanically removed by the scraper. By removing the toner, the untransferred toner adhering to the untransferred toner collecting brush member can be recovered and removed more smoothly.

  Further, a voltage having a polarity opposite to that of the untransferred toner is applied to the untransferred toner recovery brush member, and a voltage having the same polarity as that of the untransferred toner is applied to the transfer residual toner recovery brush member. May be.

  In such a configuration, a voltage having a polarity opposite to that of the untransferred toner is applied to the untransferred toner recovery brush member, and the transfer residual toner recovery brush member has the same polarity as that of the untransferred toner. Since a voltage is applied, electrostatic recovery according to the charging characteristics of each toner can be performed more effectively.

  In the above, the rotation speed of the untransferred toner recovery brush member may be set slower than the rotation speed of the untransferred toner recovery brush member.

  In such a configuration, the rotation speed of the collection brush member for untransferred toner is set to be slower than the rotation speed of the untransferred toner collection brush member. By mechanically collecting with the brush member, it is possible to more effectively prevent the toner from adhering to the image carrier again and contribute to the realization of good cleaning performance.

  The present invention is also directed to an image forming apparatus including the cleaning device.

  According to the present invention, a cleaning device that can satisfactorily clean untransferred toner and transfer residual toner on an image carrier while realizing miniaturization and long life, and an image forming apparatus using the same are simplified. The configuration can be realized at low cost.

<First embodiment>

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

  First, a schematic configuration of an embodiment of an image forming apparatus to which the present invention can be applied will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a tandem color image forming apparatus 100 according to the present invention.

  In this image forming apparatus 100, color image information of a color original read by the image reading apparatus 102, color image information sent from a personal computer or an image data input device (not shown), and the like are input, and the input image Image processing is performed on the information.

  In FIG. 1, 1Y, 1M, 1C, and 1K are image forming units that form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. The endless intermediate transfer belt 9 stretched by a roll is arranged in series in the order of 1Y, 1M, 1C, and 1K along the traveling direction. The intermediate transfer belt 9 is an intermediate transfer body to which toner images of respective colors sequentially formed by these image forming units 1Y, 1M, 1C, and 1K are transferred in a state of being superimposed on each other. The primary transfer rolls 6Y, 6M, 6C, and 6K disposed to face the photosensitive drums 2Y, 2M, 2C, and 2K, which are electrostatic latent image carriers corresponding to 1Y, 1M, 1C, and 1K, respectively. It is inserted between them and formed so as to be able to circulate in the direction of the arrow. The toner images of each color transferred onto the intermediate transfer belt 9 in a multiple manner are collectively transferred onto a recording sheet 18 as a recording medium fed from a paper feed cassette 17 or the like, and then transferred by a fixing device 15. The recording paper 18 fixed on the recording paper 18 and having a color image formed thereon is discharged to the outside.

  Here, the image reading apparatus 102 illuminates a document placed on the platen glass with a light source (not shown), and reflects a reflected light image from the document with an image reading element including a CCD sensor or the like via a scanning optical system. It is configured to read at a predetermined resolution.

  The image forming units 1Y, 1M, 1C, and 1K are configured in the same manner. Broadly speaking, the photosensitive drums 2Y, 2M, 2C, and 2K that rotate at a predetermined rotational speed in the direction of the arrow, Charge rollers 3Y, 3M, 3C, and 3K as charging means for uniformly charging the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K, and corresponding colors on the surfaces of the photosensitive drums 2Y, 2M, 2C, and 2K Exposure devices 4Y, 4M, 4C, and 4K for exposing the formed images to form electrostatic latent images, and developing devices 5Y for developing the electrostatic latent images formed on the photosensitive drums 2Y, 2M, 2C, and 2K, 5M, 5C, 5K, toner cartridges 10Y, 10M, 10C, 10K which are detachably disposed and supply toner of a predetermined color to the developing devices 5Y, 5M, 5C, 5K, and drum cleaning devices 7Y, 7M, 7C. , It is composed of a K, and the like.

  Further, in the present embodiment, the photosensitive drums 2Y, 2M, 2C, and 2K are made of an organic photosensitive material, an amorphous selenium photosensitive material, an amorphous silicon photosensitive material, or the like on the surface of a metal drum that rotates in the direction of the arrow. A photoconductor layer is formed, and the charging rolls 3Y, 3M, 3C, and 3K are in contact with the surfaces of the photoconductor drums 2Y, 2M, 2C, and 2K, and charge the photoconductor layer to a predetermined potential. It is configured.

  The image forming process in the image forming apparatus configured as described above will be described using the image forming unit 1Y that forms a yellow toner image as a representative example.

  First, the surface of the photosensitive drum 2Y is uniformly charged by the charging roll 3Y. Next, for example, based on the image information read by the image reading device 102, scanning exposure corresponding to the yellow image is performed by the laser beam output from the exposure device 4Y, and the surface of the photosensitive drum 2Y corresponds to the yellow image. An electrostatic latent image is formed.

  The electrostatic latent image corresponding to the yellow image is converted into a yellow toner image by the developing device 5Y, and is primarily transferred onto the intermediate transfer belt 9 by the pressing force and electrostatic attraction force of the primary transfer roll 6Y constituting a part of the primary transfer unit. Is done. The yellow toner remaining on the photosensitive drum 2Y after the primary transfer is scraped off by the drum cleaning device 7Y. Thereafter, the surface of the photosensitive drum 2Y is neutralized by the neutralization device 8Y and then charged again by the charging roll 3Y for the next image forming cycle.

  In the present image forming apparatus 100 that performs multicolor image formation, an image forming process similar to the above is performed at the timing in consideration of the relative position difference between the image forming units 1Y, 1M, 1C, and 1K. This is also performed in 1M, 1C, and 1K, and a full color toner image is formed on the intermediate transfer belt 9 in a superimposed state. As the intermediate transfer belt 9, for example, a flexible synthetic resin film such as polyimide is formed in a strip shape, and both ends of the synthetic resin film formed in the strip shape are connected by means such as welding, thereby being endless. What was formed in the shape of a belt can be used.

  The full-color toner image primarily transferred onto the intermediate transfer belt 9 is placed on a recording paper 18 that is conveyed to a secondary transfer position at a predetermined timing, and a backup roll 13 that supports the intermediate transfer belt 9 and the backup roll 13. The secondary transfer is performed by the pressure contact force and electrostatic attraction force with the secondary transfer roll 12 that is pressed at a predetermined timing. The residual toner on the intermediate transfer belt 9 that could not be secondarily transferred onto the recording paper 18 is conveyed to the belt cleaning device 14 as it is adhered on the intermediate transfer belt 9, and this belt cleaning device 14 performs the intermediate transfer. It is removed from the belt 9 to prepare for the next image formation.

  On the other hand, recording paper 18 having a predetermined size is fed from a paper feed cassette 17 serving as a recording paper storage unit disposed in the lower part of the image forming apparatus 100 by a paper feed roll 17a. The fed recording paper 18 is conveyed to a secondary transfer position of the intermediate transfer belt 9 by a plurality of conveying rolls 19 and registration rolls 20 at a predetermined timing. Then, as described above, the full color toner images are collectively transferred from the intermediate transfer belt 9 to the recording paper 18 by the backup roll 13 and the secondary transfer roll 12 as secondary transfer means.

  The recording paper 18 on which the full-color toner image is secondarily transferred from the intermediate transfer belt 9 is separated from the intermediate transfer belt 9 and then conveyed to the fixing device 15 disposed on the downstream side of the secondary transfer unit. The fixing device 15 fixes the toner image on the recording paper 18 with heat and pressure. The recording sheet 18 after fixing is discharged onto a discharge tray 24 through a discharge roll 23.

  Next, the belt cleaning apparatus according to the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram showing the configuration of the belt cleaning device according to the present invention.

  As shown in FIG. 2, the belt cleaning device 14 according to the present embodiment cleans untransferred toner such as patches formed in a non-image forming region (interimage) on the intermediate transfer belt 9. The transfer residual toner for cleaning the transfer residual toner is disposed adjacent to the downstream side in the traveling direction of the intermediate transfer belt 9 via the transfer toner cleaning chamber 140A, the untransferred toner cleaning chamber 140A and the partition plate 145. Cleaning chamber 140B.

  Here, the untransferred toner cleaning chamber 140A is in contact with the surface (circumferential surface) of the intermediate transfer belt 9 and is opposed to the traveling direction of the intermediate transfer belt 9 along the arrow (in this example, in the figure). , The non-transfer toner collecting brush BI rotating in the counterclockwise direction), and the conductive member rotating in the opposite direction (clockwise in the figure in this example) in contact with the surface (circumferential surface) of the brush member BI. A detoning roll DR, a scraper SR that slides on the surface of the detoning roll DR and scrapes off the toner on the surface, an auger G that transports the scraped toner, and the like are disposed. In the present embodiment, the untransferred toner recovery brush BI and the detoning roll DR can be applied with a voltage via a shaft (not shown). A voltage having a polarity opposite to the toner polarity (for example, negative polarity in this example) of the untransferred toner image formed in the inter image is applied to the roll DR.

  On the other hand, the transfer residual toner cleaning chamber 140B comes into contact with the surface (circumferential surface) of the intermediate transfer belt 9 and faces the traveling direction of the intermediate transfer belt 9 (in this example, the counterclockwise direction in the figure). ) Rotating transfer residual toner collection brush BT, and a suction device (not shown) for sucking and collecting the transfer residual toner adhering to the brush member BT are disposed through the filter F and upstream of the filter F. A cyclone type toner recovery bottle is disposed on the side. Here, the filter F plays a role of preventing the toner and dust that could not be collected by the cyclone method from passing therethrough. Similar to the untransferred toner recovery brush BI, a voltage can be applied to the transfer residual toner recovery brush BT via a rotating shaft (not shown). A voltage having a polarity opposite to the charging polarity of the toner (for example, positive polarity in this example) is applied.

  The partition member 145 that partitions the non-transfer toner cleaning chamber 140A and the transfer residual toner cleaning chamber 140B is provided with a plurality of through holes, and the transfer residual toner cleaning chamber 140B through the through holes. By the suction device provided in, a one-way air flow is formed from the untransferred toner cleaning chamber 140A toward the untransferred toner cleaning chamber 140B.

  In general, when the toner accumulated on the brush member is collected by suction through the filter F, the amount of toner toward the filter F increases as the amount of sucked toner increases, and the filter F is easily clogged. The life of the cleaning device 14 is shortened.

  Therefore, according to the belt cleaning device 14 according to the present invention configured as described above, a large amount of untransferred adhered and accumulated on the untransferred toner recovery brush BI in the upstream cleaning chamber 140A for untransferred toner. The toner is electrostatically collected by the detoning roll DR without being collected by suction. On the other hand, the transfer residual toner charged to the reverse polarity by the action of the transfer electric field is electrically collected and accumulated by the transfer residual toner recovery brush BT in the transfer residual toner cleaning chamber 140B provided on the downstream side. The low charge toner in the transfer residual toner is mechanically collected and accumulated by the sliding contact between the brush member BT and the intermediate transfer belt 9. Since the transfer residual toner including the low-charged toner adhered and accumulated on the brush member BT is collected by the suction device, the toner is separated from the untransferred toner and is collected by suction and collected according to the charging characteristics of the toner. As a result, the filter F can be prevented from being clogged, and downsizing and long life of the apparatus can be realized at low cost with a simple configuration.

  In addition, through a plurality of through holes provided in the partition plate 145, a large amount of untransferred toner is not directly sucked and collected into the toner collection bottle, but electrostatically held by a brush for low charge state of the untransferred toner. Only untransferred toner that has become cloudy due to weakening of the force can be sucked and collected from the through-hole, thereby preventing poor cleaning and obtaining better cleaning performance over a longer period of time than before. In addition, untransferred toner that was not collected on the upstream side can be collected together with the residual transfer toner by the suction device provided on the downstream side, which is more than the configuration in which both chambers are arranged in reverse. Unnecessary toner can be reliably collected and cleaned.

  In the present embodiment, the cleaning device 14 applied to the intermediate transfer belt 9 has been described. However, the present invention is not limited to such a cleaning device for the intermediate transfer belt. It can also be applied as a cleaning device for an image carrier. Further, regarding the untransferred toner, not only the untransferred toner that is not scheduled to be transferred to the recording paper 18 formed in the inter image, but also, for example, the toner on the image carrier (in this example, the intermediate transfer belt 9). A paper jam or shutdown occurs before the toner enters the transfer area, and untransferred toner remaining on the image carrier can be recovered and removed without being affected by the transfer electric field.

  Next, the results of evaluating the performance of the cleaning device configured as described above will be described below as examples.

  First, in this embodiment, the performance of the cleaning device 14 for the intermediate transfer belt 9 rotating at a process speed of 400 mm / s was experimentally verified for the high-speed and high-quality market (see FIG. 2). In addition, the diameter of the through-hole of the partition plate 145 in a present Example was 0.3 mm.

In the experiment, image charts are continuously flowed to determine whether or not an image defect has occurred on the intermediate transfer belt 9 on the downstream side of the cleaning device 14 for each of 50k, 100k, 200k, and 400k sheets. This was verified in comparison with FIG. Experimental conditions are shown below.
[Example]
Uncollected toner recovery brush BI: φ14 mm, pile length 5 mm, 6 denier, 120 / inch ² , fiber resistance 10 LogΩ nylon brush, in the same direction as the belt (the direction opposite the belt traveling direction) The shaft was rotated at 400 mm / s, and a bias voltage of +400 V was applied to the shaft.
-Detoning roll DR: A roll made of phenol resin in which carbon with a diameter of 14 mm and a resistance of 8 LogΩ is dispersed, rotated at 400 mm / s in the opposite direction to the untransferred toner collection brush BI, and a bias voltage of +800 V on the shaft. Was applied.
Scraper SR: The material was SUS, and the initial contact pressure with the detoning roll DR was set to 4.30 gf / mm.
-Transfer residual toner recovery brush BT: φ10 mm, pile length 3 mm, 2 denier, 430 lines / inch ² , nylon brush with fiber resistance 10 LogΩ, in the same direction as the belt (direction opposite to the belt traveling direction) And a bias voltage of -100 V was applied to the shaft.
[Conventional example 1]

As shown in FIG. 3A, the toner adhered and accumulated on the untransferred toner recovery brush BI and the transfer residual toner recovery brush BT is electrostatically recovered by the detoning rolls DR1 and DR2, respectively. The untransferred toner recovery brush BI, the detoning roll DR1, the scraper SR1, and the transfer residual toner recovery brush BT are the untransferred toner recovery brush BI, the detoning roll DR, The specifications are the same as those of the scraper SR and the transfer brush BT for residual toner.
Detoning roll DR2: Using a phenol resin roll in which carbon with a diameter of 10 mm and resistance of 8 LogΩ is dispersed, rotate it at 74.9 mm / s in the opposite direction to the recovery brush BT for residual transfer toner, and −500 V to the shaft The bias voltage was applied.
Scraper SR2: The material was SUS, and the initial contact pressure with the detoning roll DR was set to 4.30 gf / mm.
[Conventional example 2]

  As shown in FIG. 3B, the toner that adheres and accumulates on the untransferred toner recovery brush BI and the transfer residual toner recovery brush BT is both sucked and recovered. Both the brush BI and the transfer residual toner recovery brush BT have the same specifications as the untransferred toner recovery brush BI and the transfer residual toner recovery brush BT in the present embodiment.

  FIG. 4 shows the result of comparison and verification under such conditions.

  As shown in FIG. 4, when the transfer residual toner is rushed into the cleaner without any pre-treatment charging using the conventional electrostatic brush method (conventional example 1), 50k sheets are used, and the two brushes are sucked with air. In this case (conventional example 2), there were 100k sheets, each having a cleaning failure. On the other hand, in the cleaning device 14 according to the present example, no cleaning failure occurred even after 400k sheets, and good cleaning performance compared to the conventional example could be confirmed.

  Next, the toner recovery performance when the diameter of the through hole of the partition plate 145 according to the present invention was changed was compared and verified.

  Specifically, in the toner recovery bottle when there is no partition plate 145 and when the partition plate 145 provided with through holes of various shapes (diameters) as shown in FIGS. The toner occupancy (recovery) rate was comparatively evaluated. The verification result is shown in FIG. In this embodiment, in order to compare and verify the effect of the partition plate 145 in the suction recovery, the toner in the transfer residual toner cleaning chamber 140B (transfer residual toner and cloud-like untransferred toner) is included in the toner recovery bottle. It was configured to collect only the suction.

  As shown in FIG. 5D, when there is no partition plate 145, untransferred toner on the untransferred toner recovery brush BI for the inter image is also sucked, whereas there is a partition plate 145. It was confirmed that the replacement time of the toner collection bottle for suction collection was prolonged. Accordingly, it has been found that the presence of the partition plate 145 reduces the amount of toner passing through the filter F, extends the life of the filter F, and extends the life of the cleaning device 14.

  In addition, the shape of the holes in the partition plate 145 is such that when the holes are not opened, the toner in the cloud shape cannot be collected with air and a cleaning failure occurs. It was confirmed that the toner collection bottle replacement time becomes longer regardless of the shape of the hole.

However, as can be understood from FIG. 5D, when the hole diameter is 0.5 mm or more, toner that is not clouded is sucked and the toner collection bottle replacement time is shortened, and cleaning during suction collection is performed. It has been found that the life of the device 14 is shortened. Here, the optimum hole size is determined by the distance between the nozzle of the suction device, the partition plate 145, the brushes BI and BT, etc., but the hole diameter is roughly smaller than 0.5 mm. desirable.
<Second Embodiment>

  Next, another embodiment of the cleaning device according to the present invention will be described with reference to FIG. Note that the cleaning device 14A according to the present embodiment sucks only the low tribo (low charge) toner in the transfer residual toner that adheres and accumulates on the transfer residual toner collection brush BT by air, as compared with the previous embodiment. The members that are configured to be collected and have the same functions as those of the previous embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 6, the cleaning device 14A according to the present embodiment has a non-transferred toner image such as a patch formed in an interimage on the intermediate transfer belt 9 in a common housing. The transfer toner cleaner and the transfer residual toner cleaner are accommodated via a partition plate 146, and the collected toner is conveyed by an auger disposed under the cleaner. Note that the partition plate 146 in the present embodiment serves to easily suppress a large amount of untransferred toner from flowing out to the transfer residual toner cleaner disposed downstream. Like the partition plate 145 of the form, the two cleaning chambers 140A and 140B are not formed, and no through hole is provided.

  In the present embodiment, specifically, as a non-transfer toner collecting cleaner, a surface that contacts the surface (circumferential surface) of the intermediate transfer belt 9 and faces the traveling direction of the intermediate transfer belt 9 (in this example, The non-transfer toner collecting brush BI that rotates in the counterclockwise direction in the drawing contacts the surface (circumferential surface) of the brush member BI and rotates in the opposite direction (clockwise in the drawing in this example). An electrically conductive detoning roll DR1 and a scraper SR1 that slides on the surface of the detoning roll DR1 and scrapes off the toner on the surface are provided.

  On the other hand, as a transfer residual toner cleaner, on the downstream side of the untransferred toner collection brush BI, it contacts the surface (circumferential surface) of the intermediate transfer belt 9 and is opposed to the traveling direction of the intermediate transfer belt 9 (main book). In the example, the transfer residual toner collection brush BT that rotates in the counterclockwise direction in the drawing contacts the surface (circumferential surface) of the brush member BT, and the opposite direction (in this example, the clockwise direction in the drawing). ) And a scraper SR2 that slides on the surface of the detoning roll DR2 and scrapes off the toner on the surface. In the present embodiment, similarly to the previous embodiment, the untransferred toner recovery brush BI, the transfer residual toner recovery brush BT, and the detoning rolls DR1 and DR2 each have a voltage of a predetermined polarity. Applied.

  Further, the rotation speed of the untransferred toner recovery brush BI in the present embodiment is slower than the rotation speed of the untransferred toner recovery brush BI (about 15 to 25% of the rotation speed of the untransferred toner recovery brush BI). ).

  Then, a brush member BT is drawn by a suction device (not shown) through a filter F from a nozzle portion NZ arranged and formed at a portion further downstream of the transfer brush BT for transfer residual toner and close to the intermediate transfer belt 9. The low-charged toner inside is sucked and collected.

  Generally, the low-charged toner in the transfer residual toner collection brush BT is difficult to electrostatically collect with the detoning roll DR2, and the transfer residual toner in the transfer residual toner adhered and accumulated in the transfer residual toner collection brush BT. Since the ratio of the reversely charged toner (toner charged to the opposite polarity to the untransferred toner) and the lowly charged toner is approximately 1: 1, according to the cleaning device 14A according to the present embodiment configured as described above, By sucking and collecting only the low charge toner in the transfer residual toner recovery brush BT, the reversely charged toner and the low charge toner in the transfer residual toner recovery brush BT, as in the cleaning device 14 according to the previous embodiment. The life of the filter F can be extended approximately twice as long as the configuration in which both are sucked and collected together. In addition, a small amount of cloud-like toner in the untransferred toner is also used for the transfer residual toner whose rotation speed is set to be slow due to a one-way flow from the untransferred toner recovery brush BI to the transfer residual toner recovery brush BT. After being guided to the recovery brush BT and mechanically recovering the cloud-like toner by the brush member BT, the toner can be recovered by suction from the nozzle portion NZ.

  Further, in the cleaning device 14A according to the present embodiment, as a result of performing the verification evaluation of the cleaning performance similar to that of the previous embodiment, it is possible to obtain better cleaning performance as compared with the cleaning device having the conventional configuration. It could be confirmed.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. It is a schematic diagram which shows the structure of the cleaning apparatus which concerns on one embodiment of this invention. It is a figure which shows typically the structure of the cleaning apparatus of the conventional structure used for the comparison verification with the cleaning apparatus which concerns on this invention. It is a figure which shows the result of having performed comparison verification with the cleaning apparatus which concerns on this invention, and the cleaning apparatus of a conventional structure. It is a figure which shows the content and result of the comparison verification performed by changing the shape of the partition plate of the cleaning apparatus which concerns on one embodiment of this invention. It is a schematic diagram which shows the structure of the cleaning apparatus which concerns on another embodiment of this invention.

Explanation of symbols

  1Y-1K: image forming unit, 2Y-2K: photosensitive drum, 3Y-3K: charging roll, 4Y-4K: exposure device, 5Y-5K: developing device, 6Y-6K: primary transfer roll, 7Y-7K: drum Cleaning device, 8Y: Static elimination device, 9: Intermediate transfer belt, 10Y-10K: Toner cartridge, 12: Secondary transfer roll, 13: Backup roll, 14, 14A: Cleaning device, 15: Fixing device, 18: Recording paper, 100: Image forming apparatus, 140A: Untransferred toner cleaning chamber, 140B: Untransferred toner cleaning chamber, 145: Partition plate, BI: Untransferred toner collection brush, BT: Untransferred toner collection brush, DR: Toning roll, F: filter, NZ: nozzle part, SR: scraper

Claims (9)

A rotatable image carrier on which a toner image to be transferred to a recording medium is formed in a predetermined image forming area on the surface and an untransferred toner image is formed in a non-image forming area;
A collection brush member for untransferred toner that is formed in contact with the peripheral surface of the image carrier and is rotatable, and that cleans the untransferred toner;
A transfer residual toner recovery brush member that is formed to be rotatable in contact with the peripheral surface of the image carrier adjacent to the untransferred toner recovery brush and that cleans the transfer residual toner in the image forming region;
The toner accumulated on the untransferred toner collecting brush member is electrostatically collected and removed, and the toner accumulated on the untransferred toner collecting brush member is collected and removed by suction through a filter. A cleaning device characterized.   The untransferred toner collection brush member and the untransferred toner collection brush member are separated from each other by a partition plate, and the partition plate has a plurality of through holes, and the untransferred toner The cleaning apparatus according to claim 1, wherein a one-way air flow path from the recovery brush member to the transfer brush for residual toner is formed.   2. The cleaning device according to claim 1, wherein, among the toner adhered and accumulated on the transfer residual toner recovery brush member, only the toner in a low charge state is recovered and removed by suction.   4. The untransferred toner recovery brush member is disposed upstream of the untransferred toner recovery brush member along a rotation direction of the image carrier. A cleaning device according to claim 1.   5. The cleaning device according to claim 1, wherein the untransferred toner collection brush member and the untransferred toner collection brush member are configured to be able to apply a cleaning voltage.   The untransferred toner recovery brush member includes a conductive roll formed in contact with the brush member and rotatable, and a scraper that contacts the roll and mechanically removes toner on the roll surface. The cleaning device according to claim 1, further comprising:   A voltage having a polarity opposite to that of the untransferred toner is applied to the recovery brush member for untransferred toner, and a voltage having the same polarity as that of the untransferred toner is applied to the recovery brush member for residual transfer toner. The cleaning apparatus according to claim 1, wherein   The cleaning device according to claim 1, wherein a rotation speed of the recovery brush member for untransferred toner is set slower than a rotation speed of the recovery brush member for untransferred toner.   An image forming apparatus comprising the cleaning device according to claim 1.

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