JP2006189500A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus equipped with a cleaning device capable of surely electrostatically collecting both of toner having a positive polarity and toner having a negative polarity from the surface of a photoreceptor, and realizing low cost and small space by reducing the number of parts. <P>SOLUTION: AC voltage is applied to a cleaning brush 34 so as to attract the toner having the negative polarity and the positive polarity adhering to the surface of a photoreceptor 12. A 1st collection roll 38 and a 2nd collection roll 44 are disposed at adjacent positions to the cleaning brush 34. As to the DC component applied to the 1st collection roll 38 and the DC component applied to the 2nd collection roll 44, their absolute values are equal and their polarities are reverse. Then, the toner having the negative polarity is collected to the 1st collection roll 38 and the toner having the positive polarity is collected to the 2nd collection roll 44. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention performs a step of transferring a visualized image, which is visualized by supplying a developer to an electrostatic latent image, onto a recording sheet via a transfer member to form an image. The present invention relates to a cleaning device that cleans the residual amount of the developer generated in step 1 and an image forming apparatus including the cleaning device.

  2. Description of the Related Art Conventionally, transfer-type image forming apparatuses such as copying machines, printers, and facsimiles using a transfer type electrophotographic system form an electrostatic latent image on a photosensitive member by charging exposure and supply, for example, negatively charged toner. Then, the toner is developed (development) by adhering the toner according to the charge amount of the electrostatic latent image, and the toner image which is the visualized image is transferred from the photosensitive member to the intermediate transfer member (transfer roll, The image is formed by transferring to a recording sheet via a transfer belt or the like and fixing the toner image on the recording sheet.

  However, normally, the toner of the toner image formed on the surface of the photoreceptor is not completely transferred to a transfer material such as recording paper, and a part of the toner remains on the surface of the transfer body. Therefore, in order to prevent the remaining toner from adversely affecting the next image formation, the image forming apparatus has a cleaning device for electrostatically collecting and cleaning the toner remaining on the surface of the transfer body after the transfer. I have.

  The cleaning device includes a cleaning brush that electrostatically adsorbs residual toner on the surface of the transfer body, a recovery roll that recovers toner adsorbed by the cleaning brush, and a scraper that scrapes off the toner collected by the recovery roll from the recovery roll. It is common.

  A DC voltage is generally applied to the cleaning brush, and the cleaning brush is charged with a polarity opposite to the polarity of the toner. In this way, residual toner such as the surface of the transfer body is attracted and held between the brush hairs by electrostatic attraction. Subsequently, the residual toner adsorbed on the cleaning brush is recovered to the recovery roll side as the cleaning brush rotates. Further, the toner collected on the collecting roll is scraped off by a scraper. In this way, the toner remaining on the surface of the transfer body and the like is electrostatically collected while preventing the toner from being scattered and adhering to the cleaning brush by an amount larger than the allowable amount.

  By the way, depending on the electrophotographic process, toners of both polarities may exist in the toner. In such a case, only by applying the DC voltage as described above to the cleaning brush provided in the cleaning device, only the toner of one polarity can be recovered, and the toner of the other polarity cannot be recovered. If the apparatus is used for a long period of time in such a state, the toner remaining on the surface of the transfer body or the like will increase. Accordingly, it is known that the cleaning performance gradually deteriorates.

  In order to eliminate the above-described problems, both a cleaning brush that applies one polarity and a cleaning brush that applies the other polarity are necessary. For this reason, two collecting rolls for collecting the toner from both cleaning brushes and two scrapers for scraping off the toner from the collecting roll are required, resulting in a large apparatus.

In order to solve the above-mentioned problem, by using an alternating voltage having an amplitude within a range where no discharge occurs, by alternately applying a positive voltage and a negative voltage to one cleaning brush, not only a positive polarity toner but also a negative polarity toner can be obtained. A cleaning device that can be collected has been proposed (see Patent Document 1 and Patent Document 2).
JP-A-4-151187 JP-A-8-194418

  However, in the methods of Patent Document 1 and Patent Document 2, bipolar toner can be electrostatically adsorbed by only one cleaning brush, but bipolar toner is present in one brush. Such bipolar toner adsorbed on the cleaning brush cannot be completely recovered by one recovery roll.

  In consideration of the above-described facts, the present invention reliably collects both positive and negative polarity toners electrostatically from the surface of the transfer body, and enables reduction in cost and space with a small number of parts. It is an object of the present invention to obtain a cleaning device that performs cleaning and an image forming apparatus that includes the cleaning device.

  The invention of claim 1 includes a step of transferring a visualized image, which is visualized by supplying a developer to the electrostatic latent image, onto a recording sheet via a transfer member to form an image. A cleaning device that cleans a residual amount of the developer generated by execution of the cleaning device, and includes applying at least an alternating voltage and a voltage that changes a direction of an electric field between the developer and the transfer body. In addition, a cleaning unit for electrostatically collecting and holding the developer after transfer on the transfer body and a developer electrostatically held by the cleaning unit are collected. And a first recovery voltage applying means for applying a voltage to the first recovery member that makes the direction of the electric field between the cleaning means and the first recovery member in one direction, The cleaning means is electrostatically maintained. A second recovery member that recovers the developer of the other polarity among the developers to be applied, and a voltage that makes the direction of the electric field between the cleaning unit and the second recovery member in one direction the second recovery member. And a second recovery voltage applying means for applying to the member.

  According to the first aspect of the present invention, an image is formed by transferring a visualized image, which is visualized by supplying a developer to the electrostatic latent image, onto a recording sheet via a transfer member. A cleaning device cleans the residual amount of the developer generated by executing the process.

  After the transfer, a cleaning unit applies a voltage that changes the direction of the electric field between the transfer member on which the developer remains, including at least an alternating voltage, to the preset specific transfer member, and performs the development. Electrostatic residue is collected and retained electrostatically.

  Since the cleaning means applies a voltage that changes the direction of the electric field, the developer having both positive and negative polarities can be collected and held.

  Subsequently, the first recovery member recovers developer of one polarity among the developers electrostatically held by the cleaning unit, and the second recovery member electrostatically holds the cleaning unit. The developer having the other polarity is recovered.

  By the way, it is the first recovery voltage application means that applies a voltage to the first recovery member. The first recovery voltage application unit applies a voltage to the first recovery member so that the electric field between the cleaning unit and the first recovery member is in one direction.

  On the other hand, it is the second recovery voltage application means that applies a voltage to the second recovery member. The second recovery voltage application means applies a voltage to the second recovery member so that the direction of the electric field between the cleaning means and the second recovery member is one direction.

  The cleaning unit holds a developer having both a positive polarity and a negative polarity. Since the first recovery member has one direction of the electric field between the first recovery member and the cleaning unit, the developer with one polarity can be adsorbed. Since the second recovery member has a single electric field with respect to the cleaning unit, the second recovery member adsorbs the developer having the other polarity different from the one polarity that can be recovered by the first recovery member. be able to. Thus, the developer having both the positive polarity and the negative polarity can be recovered from the cleaning means by the first recovery member and the second recovery member.

  Therefore, according to the present invention, it is possible to recover the developer having both the positive polarity and the negative polarity from the transfer member.

  According to a second aspect of the present invention, there is provided a step of forming an image by transferring a visualized image, which is visualized by supplying a developer to the electrostatic latent image, onto a recording sheet via a transfer member. A cleaning device that cleans a residual amount of the developer generated by execution of the cleaning device, and includes applying at least an alternating voltage and a voltage that changes a direction of an electric field between the developer and the transfer body. In addition, a cleaning unit for electrostatically collecting and holding the developer after transfer on the transfer body and a developer electrostatically held by the cleaning unit are collected. An AC voltage having the same phase as the AC voltage applied to the cleaning means so that the direction of the electric field between the first recovery member and the cleaning means and the first recovery member is unidirectional and constant. The first recovery member A first recovery voltage applying means to be applied; a second recovery member for recovering the developer of the other polarity among the developers electrostatically held by the cleaning means; the cleaning means and the second recovery Second recovery voltage applying means for applying an AC voltage in phase with the AC voltage applied to the cleaning means to the second recovery member so that the direction of the electric field between the members is unidirectional and constant. It is characterized by having.

  According to the second aspect of the present invention, the visualized image that is visualized by supplying the developer to the electrostatic latent image is transferred to the recording paper via the transfer member, thereby forming an image. A cleaning device cleans the residual amount of the developer generated by executing the process.

  After the transfer, a cleaning unit applies a voltage that changes the direction of the electric field between the transfer member on which the developer remains, including at least an alternating voltage, to the preset specific transfer member, and performs the development. Electrostatic residue is collected and retained electrostatically.

  Since the cleaning means applies a voltage that changes the direction of the electric field, the developer having both positive and negative polarities can be collected and held.

  Subsequently, the first recovery member recovers developer of one polarity among the developers electrostatically held by the cleaning unit, and the second recovery member electrostatically holds the cleaning unit. The developer having the other polarity is recovered.

  By the way, it is the first recovery voltage application means that applies a voltage to the first recovery member. The first recovery voltage application unit applies a voltage to the first recovery member so that the electric field between the cleaning unit and the first recovery member is in one direction.

  On the other hand, it is the second recovery voltage application means that applies a voltage to the second recovery member. The second recovery voltage application means applies a voltage to the second recovery member so that the direction of the electric field between the cleaning means and the second recovery member is one direction.

  The cleaning unit holds a developer having both a positive polarity and a negative polarity. Since the first recovery member has one direction of the electric field between the first recovery member and the cleaning unit, the developer with one polarity can be adsorbed. Since the second recovery member has a single electric field with respect to the cleaning unit, the second recovery member adsorbs the developer having the other polarity different from the one polarity that can be recovered by the first recovery member. be able to. Thus, the developer having both the positive polarity and the negative polarity can be recovered from the cleaning means by the first recovery member and the second recovery member.

  Further, since an AC current having the same phase is applied to the cleaning means, the first recovery member, and the second recovery member, it occurs between the cleaning means, the first recovery member, and the second recovery member. The potential difference is constant. If the potential difference generated between the cleaning means and the first recovery member and the second recovery member is large, discharge may occur and the polarity of some toner may be reversed. The potential difference does not become too large, and the above problem does not occur.

  Therefore, according to the present invention, it is possible to recover the developer having both the positive polarity and the negative polarity from the transfer member.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the cleaning unit includes a roll-shaped cleaning brush that rotates relative to the specific transfer member.

  According to a third aspect of the present invention, the cleaning means is a roll-shaped brush that rotates in contact with the specific transfer member. Therefore, the developer attracted from the transfer body is easily adsorbed.

  According to a fourth aspect of the invention, there is provided the first aspect of the invention according to any one of the first to third aspects, wherein the first collecting member contacts the first collecting member and scrapes off the developer collected by the first collecting member. And a second contact member that contacts the second recovery member and scrapes off the developer recovered by the second recovery member.

  According to the invention of claim 4, the first recovery member and the second recovery member are in contact with the first contact member or the second contact member that scrape off the recovered developer, respectively. Therefore, the developer collected by the first collecting member and the second collecting member is scraped off, and the first collecting member and the second collecting member are held by the cleaning unit with a small amount of adhering developer. The developed developer can be recovered.

  According to a fifth aspect of the present invention, the cleaning apparatus according to any one of the first to fourth aspects is provided.

  According to the invention of claim 5, after the transfer, the cleaning device electrostatically collects and holds the residual amount of the developer from the transfer body on which the developer remains.

  Examples of the transfer member include an image carrier on which a visualized image is formed, a transfer unit that transfers a visualized image formed on the image carrier directly or via an intermediate transfer member, and Applicable to intermediate transfer members.

  As described above, the present invention reliably collects both positive and negative polarity toners electrostatically from the surface of the photoreceptor, and can reduce the cost and space with a small number of parts. The present invention has an excellent effect of obtaining a cleaning device and an image forming apparatus including the cleaning device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, specific numerical values may be given for convenience of explanation, but the present invention is of course not limited to these numerical values.

  As shown in FIG. 1, the color image forming apparatus 10 includes a photoreceptor 12 that rotates in the direction of arrow A.

  A charging roll 14 that uniformly charges the photosensitive surface of the photosensitive member 12 is in contact with the photosensitive surface of the photosensitive member 12. An exposure device 16 that irradiates a light beam for writing a latent image on the photosensitive surface of the photosensitive member 12 is disposed on the downstream side of the charging roller 14 in the rotation direction of the photosensitive member 12. Further, a rotary developing device 18 for developing the latent image into a toner image is in contact with the downstream side of the exposure device 16.

  The rotary developing device 18 includes a developing unit 18Y for developing a yellow (Y) toner image, a developing unit 18M for developing a magenta (M) toner image, a developing unit 18C for developing a cyan (C) toner image, And a developing device 18K that develops a black (K) toner image. For example, when developing a toner image corresponding to Y-color image data, the developing device 18Y rotates by rotating the rotary developing device 18. A Y-color toner image is formed on the photoconductor 12 in the vicinity of the photoconductor 12 and developed by the developing unit 18Y.

  An intermediate transfer belt 20 is in contact with the rotary developing device 18 on the downstream side in the rotation direction of the photosensitive member 12.

  The intermediate transfer belt 20 is wound around belt conveying rolls 24A, 24B, 24C, and 24D so as to contact the surface of the photoreceptor 12, and rotates in the direction of arrow B. A primary transfer roll 22 is disposed at a portion where the intermediate transfer belt 20 and the photoconductor 12 abut, and the primary transfer roll 22 has a polarity opposite to the charging polarity of the toner image formed on the photoconductor 12. A voltage is applied to the intermediate transfer belt 20, and a toner image is electrostatically attracted from the photoconductor 12 to the intermediate transfer belt 20 to be primarily transferred.

  The printer 10 includes a paper feed tray 26 at the bottom. The recording paper P set in the paper feed tray 26 is fed one by one from the paper feed tray 26 to the downstream side in the transport direction in the direction of arrow C and transported to the transfer unit 28.

  The transfer unit 28 is provided with a belt conveyance roll 24A around which the intermediate transfer belt 20 is wound, and a secondary transfer roll 28A pressed against the belt conveyance roll 24A. The secondary transfer roll 28A rotates in the arrow D direction. The intermediate transfer belt 20 is sandwiched between the nip portion of the belt conveyance roll 24A and the secondary transfer roll 28A, and the toner image is transferred from the intermediate transfer belt 20 when the recording paper P passes through the nip portion. It is like that.

  A fixing unit 30 is disposed downstream of the transfer unit 28 in the transport direction. The fixing unit 30 is provided with a heat roll 30A that becomes high temperature and a backup roll 30B that is in pressure contact with the heat roll 30A, and the recording paper P has a nip portion between the heat roll 30A and the backup roll 30B. When passing, the toner is melted and solidified to be fixed on the recording paper P. The recording paper P is discharged by a paper discharge roll (not shown) disposed on the downstream side of the fixing unit 30 in the transport direction.

  Next, a cleaning device 32 for cleaning the toner remaining on the photoreceptor 12 after the transfer will be described with reference to FIG.

  A cleaning brush 34 is disposed on the downstream side of the intermediate transfer belt 20 in the rotation direction of the photoconductor 12.

  The cleaning brush 34 has a brush shape in which a large number of hairs are planted around. The cleaning brush 34 is rotatable about a rotation axis parallel to the photoconductor 12 and is rotated so as to relatively move in opposite directions at the contact portion with the photoconductor 12.

  The cleaning brush 34 is connected to a cleaning power source 36 that can apply an AC voltage. The cleaning brush 34 adsorbs negative polarity and positive polarity toner adhering to the surface of the photoreceptor 12 by the voltage.

  The cleaning brush 34 is provided with a first collection roll 38 and a second collection roll 44 adjacent to each other, and the first collection roll 38 and the second collection roll 44 are provided with a cleaning brush. The toner adhering to 34 is collected.

  The first recovery roll 38 is connected to a first recovery superimposed power source 40 that can apply a voltage obtained by superimposing an alternating voltage and a direct current voltage. The first collection superimposed power supply 40 applies an AC voltage having the same phase as the AC voltage applied to the cleaning power supply 36 by the cleaning brush 34 to the first collection roll 38.

  Similarly, the second collection roll 44 is connected to a second collection superimposed power supply 46 capable of applying a voltage obtained by superimposing an AC voltage and a DC voltage. The second collection superimposed power supply 46 applies an AC voltage having the same phase as the AC voltage applied to the cleaning power supply 36 by the cleaning brush 34 to the second collection roll 44.

  Further, the direct current component applied to the first recovery roll 38 and the direct current component applied to the second recovery roll 44 have the same absolute value and opposite polarity.

  Thus, since the AC voltage applied to the cleaning brush 34 and the AC voltage applied to the first recovery roll 38 and the second recovery roll 44 are in phase, a constant potential difference always occurs. It will be. In this way, the positive polarity and negative polarity toner adsorbed between the cleaning brush 34 and the first collection roll 38 and the second collection roll 44 are transferred from the cleaning brush 34 to the first collection roll 38 or the second collection roll 38. Since an electric field is generated in the direction of movement to the collection roll 44, the toner is collected by the first collection roll 38 or the second collection roll 44.

  Further, a first scraper 42 is disposed at an adjacent position on the first collecting roll 38, and the first scraper 42 removes the toner collected on the first collecting roll 38 to the first. The scraping roll 38 is scraped off.

  Similarly, a second scraper 48 is disposed at an adjacent position on the second collection roll 44, and the second scraper 48 supplies the toner collected on the second collection roll 44 to the second collection roll 44. The second collecting roll 44 is scraped off.

  The cleaning device 32 includes a recovery auger (not shown) in the vicinity of the first scraper 42 and the second scraper 48, and the residual scraped off from the first recovery roll 38 and the second recovery roll 44. The toner is conveyed outside the cleaning device 32.

  Here, the relationship between the surface potential of the photoconductor 12 and the applied voltage to the cleaning brush 34 and the relationship between the applied voltage to the cleaning brush 34, the first collection roll 38 and the second collection roll 44 will be described.

  As shown in FIG. 3A, if the surface potential of the photoconductor 12 after transfer is 0 V indicated by an arrow 3A1, the DC component of the voltage applied to the cleaning brush 34 is set to 0 V, and an AC voltage is superimposed. To do. In FIG. 3A, voltages of Vdc = 0V and Vpp = 600V are applied. An arrow 3A2 indicates an electric field where negative polarity toner is captured by the cleaning brush 34 from the photoconductor 12, and an arrow 3A3 indicates an electric field where positive polarity toner is captured by the cleaning brush 34 from the photoconductor 12. It is. By doing so, both the positive polarity toner and the negative polarity toner on the surface of the photoconductor 12 are cleaned from the surface of the photoconductor 12 to the cleaning brush 34 by a potential difference of 300V.

  Further, as shown in FIG. 3B, if the surface potential of the photoreceptor 12 after the transfer is approximately −100V indicated by the arrow 3B1, the DC component of the voltage applied to the cleaning brush 34 is set to −100V. Furthermore, an alternating voltage is superimposed. In FIG. 3B, voltages of Vdc = −100V and Vpp = 600V are applied. An arrow 3B2 indicates an electric field where negative polarity toner is captured by the cleaning brush 34 from the photoconductor 12, and an arrow 3B3 indicates an electric field where positive polarity toner is captured by the cleaning brush 34 from the photoconductor 12. It is. By doing so, both the positive polarity toner and the negative polarity toner on the surface of the photoconductor 12 are cleaned from the surface of the photoconductor 12 to the cleaning brush 34 by a potential difference of 300 V, as in FIG.

  In this way, a DC component voltage corresponding to the surface potential of the photoconductor 12 after transfer may be applied to the cleaning brush 34.

  Next, voltage application to the first collection roll 38 and the second collection roll 44 will be described. As shown in FIG. 3A, when the applied voltages to the cleaning brush 34 are Vdc = 0V and Vpp = 600V, and toner of both polarities is cleaned, As in A), an AC voltage having the same phase as that of the cleaning brush 34 is applied at Vdc = + 300 V and Vpp = 600 V. By doing so, a potential difference of 300 V is always generated between the cleaning brush 34 and the first collection roll 38. Then, the negative polarity toner moves from the cleaning brush 34 to the first collection roll 38 according to the direction of the electric field indicated by the arrow 4A.

  Similarly, an AC voltage having the same phase as that of the cleaning brush 34 is applied to the second recovery roll 44 at Vdc = −300 V and Vpp = 600 V. By doing so, a potential difference of −300 V is always generated between the cleaning brush 34 and the second collection roll 44. Then, the positive polarity toner moves from the cleaning brush 34 to the second collection roll 44 according to the direction of the electric field indicated by the arrow 4B.

  Next, a cleaning device 50 that cleans toner adhering to the secondary transfer roll 28A after transfer will be described with reference to FIG.

  A cleaning brush 52 and a cleaning brush 52 are disposed on the downstream side of the intermediate transfer belt 20 in the rotation direction of the secondary transfer roll 28A.

  The cleaning brush 52 is connected to a cleaning power supply 54 for applying an AC voltage, like the cleaning brush 34 for cleaning the photosensitive member 12.

  The voltage applied by the cleaning power supply 54 is determined by the surface potential of the secondary transfer roll 28 </ b> A, similarly to the voltage applied by the cleaning power supply 36 to the cleaning brush 34 that cleans the photosensitive member 12.

  The cleaning brush 52 is provided with a first collection roll 56 and a second collection roll 62 adjacent to each other, and the first collection roll 56 and the second collection roll 62 are cleaned. The toner adhering to the brush 52 is collected.

  The first recovery roll 56 is connected to a first recovery superimposed power source 58 that applies an AC voltage having the same phase as the AC voltage applied to the cleaning brush 52, and the second recovery roll 62 includes A second superimposed power supply 64 for applying an AC voltage having the same phase as the AC voltage applied to the cleaning brush 52 is connected.

  Further, the direct current component applied to the first recovery roll 56 and the direct current component applied to the second recovery roll 62 have the same absolute value and opposite polarity.

  Thus, like the cleaning device 32, an electric field in the direction in which the adsorbed positive polarity toner moves from the cleaning brush 52 to the first recovery roll 56, between the cleaning brush 52 and the first recovery roll 56, In addition, since an electric field is generated between the cleaning brush 52 and the second collection roll 62 in the direction in which the adsorbed negative polarity toner moves from the cleaning brush 52 to the second collection roll 62, the toner is Are collected by the second collection roll 56 or the second collection roll 62.

  Further, the first recovery roll 56 is provided with a first scraper 60 at an adjacent position, and the second recovery roll 62 is provided with a second scraper 66 at an adjacent position. The scraped toner is scraped off.

  The cleaning device 50 includes a recovery auger (not shown) in the vicinity of the first scraper 60 and the second scraper 66, and the residual scraped off from the first recovery roll 56 and the second recovery roll 62. The toner is conveyed outside the cleaning device 50.

  Hereinafter, the flow until the toner image is transferred to the recording paper P will be described.

  When the photoreceptor 12 rotates counterclockwise in the figure, first, the photosensitive surface is uniformly charged to a predetermined polarity potential by the charging roll 14.

  When the photosensitive member 12 further rotates, the charged surface of the photosensitive surface is exposed by the exposure device 16, and the potential of the exposed portion of the charged surface is lowered to form an electrostatic latent image. Thereafter, the rotary developing device 18 develops and visualizes the electrostatic latent image by electrically attaching the developing toner charged to the same polarity as the charged polarity of the photoreceptor 12 to the potential lowering portion of the charging surface. . Then, the toner is electrically attracted to the primary transfer roll 22 to which a transfer voltage having a polarity opposite to that of the toner is applied. As a result, the toner image is transferred from the photoreceptor 12 to the intermediate transfer belt 20.

  Here, when the toner image is transferred from the photoconductor 12 to the intermediate transfer belt 20, untransferred toner remaining on the photoconductor 12 without being transferred to the intermediate transfer belt 20 is generated. Further, retransfer toner is generated in which the toner transferred to the intermediate transfer belt 20 on the upstream side is offset to the photoreceptor 12 on the downstream side. For this reason, it is necessary to remove the transfer residual toner and the retransfer toner from the photoreceptor 12. Therefore, the voltage applied to the first collection roll 38 and the second collection roll 44 that are in contact with the cleaning brush 34 is adjusted, and the transfer residual toner and retransfer toner on the photoconductor 12 are transferred to the photoconductor 12. Remove from.

  Further, the toner image transferred to the intermediate transfer belt 20 is electrically drawn by the transfer unit 28 to the secondary transfer roll 28A to which a transfer voltage having a polarity opposite to that of the toner is applied. As a result, the toner image is transferred from the intermediate transfer belt 20 to the recording paper P.

  Here, the secondary transfer roll 28A is in direct contact with the intermediate transfer belt 20 when the recording paper P is not passing through. For this reason, the toner on the intermediate transfer belt 20 adheres to the secondary transfer roll 28A. This toner needs to be removed from the secondary transfer roll 28A. Therefore, the voltage applied to the first collection roll 56 and the second collection roll 62 that are in contact with the cleaning brush 52 is adjusted to remove the toner on the secondary transfer roll 28A.

  Next, an experiment for evaluating the present embodiment will be described.

  Using the chart 200 shown in FIG. 6 as a print chart, the cleaning performance was examined. In the chart 200, a long solid belt-like PK 300% (black made by overlapping 100% solids of Y, M, and C) images 202 and a long solid belt-like M100% image 204 are arranged side by side. . The PK 300% image 202 has a negative polarity C transfer residual toner, and the M100% image 204 has a positive polarity M retransfer toner.

  The cleaning brush 34 is applied with an AC voltage of Vdc = −0 V, Vpp = 600 V, and 1.6 kHz (the voltage of the present embodiment). The first recovery roll 38 is supplied with Vdc = + 300V, Vpp = 600V, 1.6 kHz, and an AC voltage in phase with the cleaning brush 34. The second recovery roll 44 is supplied with Vdc = −300V, Vpp = 600V. , An alternating voltage having the same phase as that of the cleaning brush 34 is applied at 1.6 kHz.

  As a comparative example, the cleaning brush 34 and the first recovery roll 38 to which a voltage similar to the voltage of the present embodiment is applied by the superimposed power source 80 shown in FIG. 7A are used, and the second recovery roll 44 is used. If not (Comparative Example 1), a voltage similar to the voltage of the present embodiment is applied to the cleaning brush 90 shown in FIG. 7B, and a DC component is temporally applied to the collection roll 92 by the superimposed power supply 94. The same experiment is performed even when a voltage of Vpp = 600 V and 1.6 kHz in phase with the cleaning brush 34 that switches between Vdc = + 300 V and Vdc = −300 V is applied (Comparative Example 2).

  Each initial recovery rate is shown in Table 1, and the presence or absence of cleaning failure is summarized in Table 2.

  Under the conditions of the present embodiment, no cleaning failure occurred. On the other hand, cleaning failure occurred in the M100% image 204 in the comparative example 1 and in both the PK300% image 202 and the M100% image 204 in the comparative example 2.

  The M100% image 204 is an image in which positive polarity toner rushes into the cleaning brush 34. However, in the comparative example 1, since the second collection roll 44 that collects positive polarity toner is not provided, the M100% image 204 is removed from the cleaning brush 34. Not collected. In this way, positive polarity toner gradually accumulates on the cleaning brush 34, and it is considered that a cleaning failure has occurred. On the other hand, the PK 300% image 102 is a negative polarity toner and was collected by the first collection roll 38, so that no cleaning failure occurred.

  On the other hand, in Comparative Example 2, a cleaning failure occurred in both the PK 300% image 102 and the M100% image 104. In Comparative Example 2, a DC voltage is superimposed on an AC voltage having the same phase as that of the cleaning brush 90, and the DC voltage is switched between + 300V and −300V in a certain cycle. When + 300V is applied, the negative polarity toner in the cleaning brush 90 is collected by the collection roll 92. When −300V is applied, the positive polarity toner in the cleaning brush 90 is collected by the collection roll 92. Will be collected. In this way, it is possible to collect both negative polarity and positive polarity toners. As a result, both the PK 300% image 202 and the M100% image 204 have a recovery rate of about 60%, and good cleaning performance is obtained. I couldn't. This is because when the toner of one polarity is being collected, it is impossible to collect the toner of the other polarity. Therefore, compared to the case of always collecting (that is, the case of this embodiment), the negative polarity and This is because the recovery time has been halved for both positive and negative polarities. For this reason, in the paper passing test, toner that cannot be collected in the cleaning brush 90 is accumulated in both the PK 300% image 202 and the M100% image 204, resulting in a cleaning failure.

  Subsequently, a modified example of the voltage applied to the first collection roll 38 and the second collection roll 44 will be described. As shown in FIG. 8A, the first recovery roll 38 is connected to a first recovery DC power supply 70 that applies a voltage having only a positive polarity DC component. On the other hand, the second recovery roll 44 is connected to a second recovery DC power source 72 that applies a voltage having only a negative polarity DC component.

  As shown in FIG. 8B, the first recovery DC power supply 70 applies a voltage that causes a potential difference of at least +300 V to the voltage of the cleaning brush 34 to the first recovery roll 38. On the other hand, the second recovery DC power source 72 applies a voltage that causes a potential difference of at least −300 V to the voltage of the cleaning brush 34 to the first recovery roll 44. Thus, the negative polarity toner moves from the cleaning brush 34 to the first collection roll 38 according to the direction of the electric field indicated by the arrows 8A and 8C, while the direction of the electric field indicated by the arrows 8B and 8D. As a result, the positive polarity toner moves from the cleaning brush 34 to the second collection roll 44.

  The same evaluation was performed for the modified example. The initial recovery rates of the respective modifications are shown in Table 3, and the presence or absence of cleaning failure is summarized in Table 4.

  When only a direct current component is applied, as shown by arrows 8C and 8D in FIG. 8B, a potential difference is increased. When the potential difference is large, discharge may occur, and the polarity of some toners may be reversed. Thus, toner that cannot be recovered by the first recovery roll 38 and the second recovery roll 44 is generated, and the initial recovery rate becomes worse than when an AC voltage having the same phase as that of the cleaning brush 34 described above is applied. ing.

  However, when compared with Comparative Example 1 and Comparative Example 2, it can be seen that the initial recovery rate is high even in the modified example. As described above, in order to collect the bipolar toner, a voltage is applied to the cleaning brush 34, two recovery rolls and two scrapers are provided, and electric fields in opposite directions are applied to the respective recovery rolls. It can be seen that it is important to apply the voltage to be formed (that is, the present embodiment).

  FIG. 9 shows a color page printer 110 (hereinafter referred to as a printer), which is an image forming apparatus according to the second embodiment. In the printer 110, photoconductors 112Y, 112M, 112C, and 112K for each color of yellow, magenta, cyan, and black are arranged in parallel facing the intermediate transfer belt 120, and four colors are provided while the intermediate transfer belt 120 makes one round. This is a tandem type full-color page printer that superimposes toner images.

  In addition, about the structure and operation | movement fundamentally the same as said 1st Embodiment, the same code | symbol as the said 1st Embodiment is attached | subjected and the description is abbreviate | omitted. If there is no need to distinguish between yellow, magenta, cyan, and black colors, Y, M, C, and K after the reference numerals are omitted.

  The intermediate transfer belt 120, the charging roll 114, and the developing roll 118 are in contact with the surface of the photoconductor 112 of each color in order in the rotation direction. An exposure device 116 that exposes the surface is disposed between the charging roll 114 and the developing roll 118.

  The intermediate transfer belt 120 is wound around belt conveyance rolls 124A, 124B, 124C, and 124D so as to contact the surface of the photoreceptor 112, and a cleaning device 132 is provided in the vicinity of the belt conveyance roll 124B. .

  The cleaning device 132 is provided with a cleaning brush 134 in pressure contact with the belt conveying roll 124B.

  Here, when the toner image is transferred from the intermediate transfer belt 120 to the recording paper P, residual transfer toner that remains on the intermediate transfer belt 120 without being transferred to the recording paper P is generated. For this reason, it is necessary to remove the transfer residual toner from the intermediate transfer belt 120. Therefore, the residual transfer toner on the intermediate transfer belt 120 is removed from the intermediate transfer belt 120 by adjusting the voltage applied to the cleaning brush 134 and the first recovery roll 138 and the second recovery roll 144 that are in contact with the cleaning brush 134. To do.

  The cleaning brush 134 is connected to a cleaning power source 136 for applying an AC voltage, like the cleaning brush 34 for cleaning the photosensitive member 12.

  The voltage applied by the cleaning power source 136 is determined by the surface potential of the intermediate transfer belt 120 in the same manner as the voltage applied by the cleaning power source 36 to the cleaning brush 34 for cleaning the photosensitive member 12.

  The cleaning brush 134 is provided with a first collection roll 138 and a second collection roll 144 adjacent to each other, and the first collection roll 138 and the second collection roll 144 are cleaned. The toner attached to the brush 134 is collected.

  The first recovery roll 138 is connected to a first recovery superimposed power supply 140 that applies an AC voltage having the same phase as the AC voltage applied to the cleaning brush 134, and the second recovery roll 144 includes A second superimposed power supply 146 that applies an AC voltage in phase with the AC voltage applied to the cleaning brush 134 is connected.

  Further, the direct current component applied to the first collection roll 138 and the direct current component applied to the second collection roll 144 have the same absolute value and opposite polarity.

  Thus, like the cleaning device 32, an electric field in the direction in which the adsorbed positive polarity toner moves from the cleaning brush 134 to the first recovery roll 138, between the cleaning brush 134 and the first recovery roll 138, In addition, an electric field is generated between the cleaning brush 134 and the second collection roll 144 in the direction in which the adsorbed negative polarity toner moves from the cleaning brush 134 to the second collection roll 144. Is collected by the second collection roll 144 or the second collection roll 144.

  Further, the first recovery roll 138 is provided with a first scraper 142 at an adjacent position, and the second recovery roll 144 is provided with a second scraper 148 at an adjacent position. The scraped toner is scraped off.

  Further, the cleaning device 132 includes a recovery auger (not shown) in the vicinity of the first scraper 142 and the second scraper 148, and the residual scraped off from the first recovery roll 138 and the second recovery roll 144. The toner is conveyed outside the cleaning device 132.

  FIG. 10 shows a color page printer 160 (hereinafter referred to as a printer) which is an image forming apparatus according to the third embodiment. In addition, about the structure and operation | movement fundamentally the same as the said 1st Embodiment and the said 2nd Embodiment, the same code | symbol as the said 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

  The printer 160 is a tandem type full-color page printer, and yellow, magenta, cyan, and black color photoconductors 112Y, 112M, 112C, and 112K are arranged in parallel facing the transfer conveyance belt 170, and the transfer is performed. In this method, four color toner images are directly superimposed on the recording paper P transported to the transport belt 170.

  The transfer conveyance belt 170 is wound around belt conveyance rolls 174A, 174B, 174C, and 174D so as to come into contact with the surface of the photoreceptor 112, and a cleaning device 182 is provided in the vicinity of the belt conveyance roll 174A. .

  The cleaning device 182 includes a cleaning brush 184 that is pressed against the belt transport roll 174A.

  Here, when the toner image is transferred from the transfer conveyance belt 170 to the recording paper P, residual transfer toner that remains on the transfer conveyance belt 170 without being transferred to the recording paper P is generated. Therefore, it is necessary to remove the transfer residual toner from the transfer conveyance belt 170. Therefore, the voltage applied to the cleaning brush 184 and the first recovery roll 188 and the second recovery roll 194 that are in contact with the cleaning brush 184 is adjusted to remove the transfer residual toner on the transfer conveyance belt 170 from the transfer conveyance belt 170. To do.

  The cleaning brush 184 is connected to a cleaning power source 186 that applies an AC voltage, similarly to the cleaning brush 34 that cleans the photosensitive member 12.

  The voltage applied by the cleaning power source 186 is determined by the surface potential of the transfer / conveying belt 170 in the same manner as the voltage applied by the cleaning power source 36 to the cleaning brush 34 for cleaning the photosensitive member 12.

  The cleaning brush 184 is provided with a first collection roll 188 and a second collection roll 194 at adjacent positions, and the first collection roll 188 and the second collection roll 194 are cleaned. The toner attached to the brush 184 is collected.

  The first recovery roll 188 is connected to a first recovery superimposed power source 190 that applies an AC voltage having the same phase as the AC voltage applied to the cleaning brush 184, and the second recovery roll 194 includes A second superimposed power supply 196 that applies an AC voltage in phase with the AC voltage applied to the cleaning brush 184 is connected.

  Further, the direct current component applied to the first recovery roll 188 and the direct current component applied to the second recovery roll 194 have the same absolute value and opposite polarity.

  Thus, like the cleaning device 32, an electric field in the direction in which the adsorbed positive polarity toner moves from the cleaning brush 184 to the first recovery roll 188, between the cleaning brush 184 and the first recovery roll 188, In addition, since an electric field is generated between the cleaning brush 184 and the second collection roll 194 in the direction in which the adsorbed negative polarity toner moves from the cleaning brush 184 to the second collection roll 194, the toner is the first Are collected by the second collection roll 188 or the second collection roll 194.

  Further, the first recovery roll 188 is provided with a first scraper 192 at an adjacent position, and the second recovery roll 194 is provided with a second scraper 198 at an adjacent position. The scraped toner is scraped off.

  The cleaning device 182 includes a recovery auger (not shown) in the vicinity of the first scraper 192 and the second scraper 198, and the residual scraped off from the first recovery roll 188 and the second recovery roll 194. The toner is conveyed outside the cleaning device 182.

  The embodiment described above does not limit the configuration of the present invention, and the AC voltage may be a rectangular wave other than a sine wave, a triangular wave, or the like.

  The cleaning of the toner remaining on the photoconductor after the transfer has been described only in the first embodiment, but the first embodiment is also applied to the photoconductors according to the second embodiment and the third embodiment. The form of cleaning device 32 is applicable.

  Further, the cleaning device 132 for cleaning the toner remaining on the intermediate transfer belt may be applied to the image forming apparatus according to the first embodiment, or the cleaning device 50 for cleaning the toner remaining on the secondary transfer roll. You may apply to the image forming apparatus which concerns on 2nd Embodiment.

1 is a schematic diagram illustrating an image forming apparatus according to a first embodiment. 1 is a schematic diagram illustrating a photoconductor of an image forming apparatus according to a first embodiment. It is a figure which shows the relationship between the surface potential of a photoconductor and an applied voltage, (A) is a case where the surface potential of a photoconductor is 0V, (B) is a case where the surface potential of a photoconductor is -100V. It is. FIG. 5 is a potential relationship diagram between a cleaning brush and a collection roll. FIG. 2 is a schematic diagram illustrating a transfer unit of the image forming apparatus according to the first embodiment. It is the print chart used for experiment. (A) is a schematic diagram of a photoconductor to which only a collecting roll to which a positive polarity DC component is applied, and (B) is a schematic diagram of a photoconductor to which a collecting roll whose DC component is reversed with time is applied. It is. (A) It is the schematic which shows the modification of the voltage application to a collection | recovery roll, (B) is an electric potential relationship figure of the cleaning brush and collection | recovery roll in this modification. It is the schematic which shows the image forming apparatus which concerns on 2nd Embodiment. It is the schematic which shows the image forming apparatus which concerns on 3rd Embodiment.

Explanation of symbols

10 Color image forming device (image forming device)
12 Photoconductor (transfer body)
14 Charging roll 16 Exposure device 18 Rotary developing device 18Y, 18M, 18C, 18K Developing device 20, 120 Intermediate transfer belt (transfer body)
22 Primary transfer roll 24A Belt transport roll 28 Transfer section 28A Secondary transfer roll (transfer body)
170 Transfer conveyor belt (transfer body)
32, 50, 132, 182 Cleaning device 34, 52, 134, 184 Cleaning brush (cleaning means)
36, 54, 136, 186 Cleaning power supply (cleaning means)
38, 56, 138, 188 First collection roll (first collection means)
40, 58, 140, 190 First recovery superimposed power source (first recovery voltage applying means)
42, 60, 142, 192 First scraper (first contact member)
44, 62, 144, 194 Second collection roll (second collection means)
46, 64, 146, 196 Second superimposed power supply (second collected voltage applying means)
48, 66, 148, 198 Second scraper (second contact member)

Claims (5)

It is generated by transferring a visualized image, which is visualized by supplying a developer to the electrostatic latent image, onto a recording sheet through a transfer body, and forming an image. A cleaning device for cleaning the residual amount of the developer,
Applying at least an alternating voltage, and applying a voltage that changes the direction of the electric field between the developer and the transfer body on which the developer remains, and electrostatically recovering the residual content of the developer after transfer on the transfer body; Cleaning means for holding;
A first recovery member for recovering one of the developers electrostatically held by the cleaning means;
A first recovery voltage applying means for applying a voltage to the first recovery member to make the direction of the electric field between the cleaning means and the first recovery member in one direction;
A second recovery member for recovering the developer of the other polarity among the developers electrostatically held by the cleaning means;
A second recovery voltage applying means for applying a voltage to the second recovery member so that the direction of the electric field between the cleaning means and the second recovery member is one direction;
A cleaning device comprising: It is generated by transferring a visualized image, which is visualized by supplying a developer to the electrostatic latent image, onto a recording sheet through a transfer body, and forming an image. A cleaning device for cleaning the residual amount of the developer,
Applying at least an alternating voltage, and applying a voltage that changes the direction of the electric field between the developer and the transfer body on which the developer remains, and electrostatically recovering the residual content of the developer after transfer on the transfer body; Cleaning means for holding;
A first recovery member for recovering one of the developers electrostatically held by the cleaning means;
An AC voltage having the same phase as the AC voltage applied to the cleaning unit is applied to the first recovery member so that the direction of the electric field between the cleaning unit and the first recovery member is unidirectional and constant. First recovery voltage application means for
A second recovery member for recovering the developer of the other polarity among the developers electrostatically held by the cleaning means;
An AC voltage having the same phase as the AC voltage applied to the cleaning means is applied to the second recovery member so that the direction of the electric field between the cleaning means and the second recovery member is unidirectional and constant. Second recovery voltage applying means for
A cleaning device comprising:   The cleaning device according to claim 1, wherein the cleaning unit includes a roll-shaped cleaning brush that rotates in contact with the specific transfer body. A first contact member that contacts the first recovery member and scrapes off the developer recovered by the first recovery member;
4. The apparatus according to claim 1, further comprising a second contact member that contacts the second collection member and scrapes off the developer collected by the second collection member. 5. The cleaning device described.   An image forming apparatus comprising the cleaning device according to claim 1.

Images