JP6236696B2 - Cleaning device - Google Patents

Description

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

  2. Description of the Related Art Conventionally, as a cleaning device used in an image forming apparatus, an apparatus that removes residual toner remaining on the surface of an image carrier without being transferred to a transfer material by contacting with a cleaning blade is known (for example, Patent Documents). 1). In such a cleaning device, the cleaning blade may become swollen due to a decrease in lubricity at the tip edge portion of the cleaning blade.

  Various techniques are known as techniques for preventing such cleaning blades from rolling. For example, in the technique described in Patent Document 1, a toner band image is formed at a timing other than the time of image formation, and the toner that forms the image reaches the tip edge portion of the cleaning blade to improve the lubricity of the cleaning blade. I am letting. However, with this technique, it is necessary to consume new toner other than during image formation. Further, it is necessary to perform an operation for forming a toner band image separately from the printing operation, which may cause a reduction in productivity.

  Therefore, in Patent Document 1, the residual toner remaining on the surface of the image carrier is recharged by a recharging means, and the recharged residual toner is temporarily collected, and then discharged to the image carrier at regular intervals. Also disclosed is a technique for supplying between an image carrier and a cleaning blade.

  Further, in Patent Document 2, in a cleaning device for an image forming apparatus, a toner having a polarity opposite to that of a toner is normally applied to the conductive fine fiber to hold the toner, while the toner is applied to the conductive fine fiber at an arbitrary timing. And a technique for discharging and supplying the toner held on the cleaning blade by applying a voltage having the same polarity as the above.

JP 2000-162894 A JP 2007-57833 A

  By the way, in Patent Document 2, a voltage having the same polarity as that of the toner is applied at an arbitrary timing to discharge the toner held on the cleaning blade. However, since the specific timing is not disclosed, the image carrier is not disclosed. It has been difficult to discharge predetermined toner when the cleaning blade is liable to be swollen while securing a certain amount of toner to be discharged to the cleaning blade.

  Accordingly, the present invention has been made to solve the above-described problem, and it is an object of the present invention to provide a cleaning device that can appropriately prevent the cleaning blade from curling while securing a certain amount of toner for ejection. And

  In order to solve the above-described problems, a cleaning device according to the present invention is a cleaning device that removes transfer residual toner remaining on the surface of an image carrier in an image forming apparatus, and is in contact with the surface of the image carrier to transfer residual toner. A conductive brush roll that removes and holds at least a part of the image bearing member, a static elimination unit that is disposed upstream of the conductive brush roll in the rotational direction of the image carrier and neutralizes the surface potential of the image carrier, and an image carrier A cleaning blade that contacts the surface of the body and removes transfer residual toner that has not been removed by the conductive brush roll among residual transfer residual toner, and detection means that detects whether the image forming apparatus is in a high-temperature and high-humidity environment And voltage switching means for switching the application of voltage to the conductive brush roll, and the voltage switching means is such that the image forming apparatus is in a high temperature and high humidity environment by the environment detection means. In case where it is detected, when the conductive brush roller is in contact with the non-image forming portion of the image bearing member, and applying the residual untransferred toner having the same polarity of the voltage to the conductive brush roller.

  In the cleaning apparatus according to the present invention, when the image forming apparatus is detected to be in a high temperature and high humidity environment by the detection means, when the conductive brush roll comes into contact with the non-image forming portion of the image carrier, the remaining transfer residue is detected. A voltage having the same polarity as the toner is applied to the conductive brush roll by the voltage switching means. Therefore, in a high temperature and high humidity environment and a non-image forming portion where the cleaning blade is relatively liable to be bent, the transfer residual toner held on the conductive brush roll is applied to the surface of the image carrier by electric repulsion. Exhales to improve lubricity. By discharging the toner to the image carrier at the most necessary timing in this way, it is possible to appropriately prevent the cleaning blade from curling while eliminating unnecessary toner discharge and securing a certain amount of toner to be discharged. it can.

  Further, the voltage switching means detects the image density of the image forming section when the detecting means detects that the image forming apparatus is in a high temperature and high humidity environment and the conductive brush roll is in contact with the image forming section of the image carrier. Accordingly, a voltage having a polarity opposite to that of the remaining transfer residual toner or a voltage having the same polarity as that of the remaining transfer residual toner may be applied to the conductive brush roll. According to this, even when the environment detection unit detects that the image forming apparatus is in a high-temperature and high-humidity environment, depending on the image density of the image forming portion of the image carrier, that is, the density of residual toner, The toner can be discharged and the toner can be collected. As a result, toner can be supplied when the cleaning blade is likely to curl, while the cleaning blade can be recovered if the cleaning blade is difficult to curl, while ensuring a certain amount of toner for ejection. Further, it is possible to appropriately suppress the cleaning blade from curling.

  The voltage switching unit applies a voltage having a polarity opposite to that of the residual transfer residual toner to the conductive brush roll when the image forming unit has a normal image density higher than a predetermined image density. Is a low image density equal to or lower than a predetermined image density, a voltage having the same polarity as that of the residual transfer residual toner may be applied to the conductive brush roll. In this case, when the image forming portion is a normal image density portion, a voltage having a polarity opposite to that of the transfer residual toner is applied to the conductive brush roll by the voltage switching unit, and when the image forming portion is a low image density portion, A voltage having the same polarity as the transfer residual toner is applied to the conductive brush roll by the voltage switching means. Therefore, when the image forming unit is a normal image density unit, the transfer residual toner can be collected and held by the conductive brush roll by electrical attraction. As a result, the collected and retained transfer residual toner can be used for discharging to the surface of the image carrier. On the other hand, when the image forming portion is a low image density portion, the transfer residual toner held on the conductive brush roll can be discharged to the surface of the image carrier by electric repulsion. As a result, the lubricity between the surface of the image carrier and the tip of the cleaning blade can be improved more appropriately.

  Further, when the A4 size printing paper is used, the predetermined image density may be such that the area ratio of the image portion to the entire area of the printing paper is 5%. In this case, the above-described effects are preferably achieved.

  The voltage switching means conducts the voltage when the conductive brush roll comes into contact with the non-image forming portion of the image carrier when the detection means detects that the image forming apparatus is a standard environment that is not a high temperature and high humidity environment. When the conductive brush roll is in contact with the image forming portion of the image carrier without applying to the conductive brush roll, a voltage having a polarity opposite to that of the residual transfer residual toner may be applied to the conductive brush roll. According to this, when the image forming apparatus is detected as a standard environment that is not a high-temperature and high-humidity environment by the detecting means, when the conductive brush roll comes into contact with the image forming portion of the image carrier, the residual transfer by the voltage switching means. A voltage having a polarity opposite to that of the remaining toner is applied to the conductive brush roll. Therefore, when the conductive brush roll comes into contact with the image forming portion of the image carrier, not in a high temperature and high humidity environment, the transfer residual toner is collected and held by the conductive brush roll. As a result, the collected and retained transfer residual toner can be used for discharging to the surface of the image carrier. Further, when the image forming apparatus is not in a high temperature and high humidity environment and the conductive brush roll is in contact with the non-image forming portion of the image carrier, no voltage is applied to the conductive brush roll. Therefore, in the case of a standard environment where the cleaning blade is less likely to bend than in a high-temperature and high-humidity environment, the transfer residual toner is not discharged even when the conductive brush roll is in contact with the non-image forming portion. Useless transfer residual toner can be prevented from being discharged.

  Also provided is a brush roll contact member that contacts the conductive brush roll, collects the transfer residual toner held by the conductive brush roll from the conductive brush roll, and applies the recovered transfer residual toner to the conductive brush roll. May be. In this case, the transfer residual toner is collected from the conductive brush roll by the brush roll abutting member, and the collected transfer residual toner is applied to the conductive brush roll, so that the transfer residual held by the conductive brush roll is applied. Toner bias can be suppressed.

  The brush roll contact member is in contact with the entire region of the conductive brush roll in the axial direction and has a spiral groove wound in one direction. The rotation direction of the brush roll contact member is clockwise and counterclockwise. It may be switched to either. In this case, in a state where the brush roll contact member having the spiral groove is in contact with the entire axial direction of the conductive brush roll, the brush roll contact member can be switched clockwise or counterclockwise to rotate. Therefore, the transfer residual toner can be uniformly applied to the entire axial direction of the conductive brush roll.

  The brush roll contact member is in contact with the entire area of the conductive brush roll in the axial direction, and has a first spiral groove wound in one direction and a second spiral groove wound in the other direction. The rotation direction of the member may be either clockwise or counterclockwise. In this case, the brush roll contact member rotates in a state in which the brush roll contact member having the first spiral groove and the second spiral groove wound in different directions is in contact with the entire axial direction of the conductive brush roll. Therefore, even if the rotation direction is either clockwise or counterclockwise, the transfer residual toner can be uniformly applied to the entire axial direction of the conductive brush roll.

Further, the resistance value of the conductive brush roll may be larger than 10 ² MΩ and smaller than 10 ⁶ MΩ, and the absolute value of the voltage applied to the conductive brush roll may be larger than 100 V and smaller than the discharge start voltage. In this case, it is preferable from the viewpoint of cleaning performance and discharging performance of the conductive brush roll.

Further, the amount of the toner including the untransferred toner discharged on the surface of the image carrier may be 1.0 × 10 ⁻⁷ g / cm ² or more. In this case, the above-described effects are preferably achieved.

  The cleaning device according to the present invention is a cleaning device that removes transfer residual toner remaining on the surface of the image carrier in the image forming apparatus, and is in contact with the surface of the image carrier to remove at least a part of the transfer residual toner. A conductive brush roll to be removed and held, a neutralizing means disposed upstream of the conductive brush roll in the rotation direction of the image carrier, and for contacting the surface of the image carrier with a charge eliminating means for neutralizing the surface potential of the image carrier. A cleaning blade that removes transfer residual toner that has not been removed by the conductive brush roll from the residual transfer residual toner, and voltage switching means that switches voltage application to the conductive brush roll. When the conductive brush roll is in contact with the image forming portion of the image carrier, if the image forming portion has a normal image density higher than a predetermined image density, the remaining When a voltage having a polarity opposite to that of the transferred residual toner is applied to the conductive brush roll and the image forming portion has a low image density equal to or lower than a predetermined image density, a voltage having the same polarity as the residual residual toner is applied to the conductive brush roll. It is characterized by being applied to a roll.

  In the cleaning device according to the present invention, when the conductive brush roll is in contact with the image forming portion of the image carrier, when the image forming portion has a normal image density, a voltage having a polarity opposite to the residual transfer residual toner is applied to the conductive brush. When the image forming unit has a low image density when applied to the roll, a voltage having the same polarity as that of the residual transfer residual toner is applied to the conductive brush roll. Therefore, when the conductive brush roll is in contact with the image forming portion of the image carrier, the transfer residual toner is collected and held by the conductive brush roll when the image forming portion is a normal image density portion. Then, when the conductive brush roll is in contact with the image forming portion of the image carrier, the collected and retained transfer residual toner is discharged to the surface of the image carrier when the image forming portion is a low image density portion. It is. As a result, the lubricity between the surface of the image carrier and the tip of the cleaning blade can be improved. As described above, it is possible to appropriately prevent the cleaning blade from curling while securing a certain amount of toner to be discharged.

  According to the present invention, it is possible to appropriately prevent the cleaning blade from curling while securing a certain amount of toner for ejection.

It is a schematic block diagram of the cleaning apparatus which concerns on one Embodiment of this invention. 1 is a schematic configuration diagram of a cleaning device according to an embodiment of the present invention viewed from the circumferential direction of a photosensitive drum. It is a timing diagram which shows an example of the timing of the operation | movement of a brush roll under a standard environment. FIG. 10 is a timing diagram illustrating an example of the operation timing of the brush roll in a high-temperature and high-humidity environment and the image forming unit has a normal image density. FIG. 10 is a timing diagram illustrating an example of the operation timing of a brush roll in a high-temperature and high-humidity environment and an image forming unit has a low image density. It is a graph which shows the appropriate value of the resistance of a brush roll in the case of applying the voltage of reverse polarity to a transfer residual toner, and an applied voltage. It is a graph which shows the appropriate value of the resistance of a brush roll when applying the voltage of the same polarity as a transfer residual toner, and an applied voltage. It is a graph which shows an example of operation | movement of the brush roll with respect to the number of printed sheets. FIG. 6 is a schematic configuration diagram of a cleaning device according to a modification as viewed from the circumferential direction of a photosensitive drum.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  First, an outline of the cleaning device according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram of a cleaning device according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of the cleaning device according to the embodiment of the present invention viewed from the circumferential direction of the photosensitive drum. However, in FIG. 2, for the sake of simplicity, the transfer belt 6, the transfer roll 7, and the charge removal unit 8 illustrated in FIG. 1 are omitted.

  As shown in FIG. 1, the cleaning device 1 according to this embodiment is disposed in a transfer unit 3 in an image forming apparatus 10. The image forming apparatus 10 is an apparatus that can form a color image using, for example, magenta, yellow, cyan, and black colors. The transfer unit 3 is a unit that transfers a toner image to printing paper, and is formed on the outer peripheral surface of the photosensitive drum 5 that is an electrostatic latent image carrier on which an image is formed on the peripheral surface. A transfer belt 6 for transferring the toner image and a transfer roll 7 for holding the transfer belt 6 together with the photosensitive drum 5 are included. The photosensitive drum 5 is made of, for example, OPC (Organic PhotoConductor). Although not shown, the image forming apparatus 10 is provided with four photosensitive drums 5 along the moving direction of the transfer belt 6 corresponding to the colors magenta, yellow, cyan, and black. .

  Printing by the image forming apparatus 10 is performed by the following process using the photosensitive drum 5. First, the surface 5a of the photosensitive drum 5 is uniformly charged to a predetermined potential (charging process). The surface 5a of the charged photosensitive drum 5 is exposed according to the image formed on the printing paper (exposure process). As a result, the potential of the exposed portion of the surface 5a of the photosensitive drum 5 is displaced, and an electrostatic latent image is formed. Toner is supplied from the toner tank provided corresponding to each photoconductor drum 5 to the surface 5a of each photoconductor drum 5, and the electrostatic latent image formed on the photoconductor drum 5 is developed (development process). As a result, a toner image is generated. The toner tank is filled with toner of each color of magenta, yellow, cyan, and black. The toner image thus formed is primarily transferred from the photosensitive drum 5 to the transfer belt 6 in a region where the photosensitive drum 5 and the transfer belt 6 face each other (transfer process). On the transfer belt 6, toner images formed on the four photosensitive drums 5 are sequentially stacked to form one stacked toner image. The laminated toner image is secondarily transferred onto the conveyed printing paper. The laminated toner image is melt-fixed by applying heat and pressure to the printing paper on which the laminated toner image is secondarily transferred (fixing step).

  The cleaning device 1 is a device for removing transfer residual toner remaining on the surface 5 a of the photosensitive drum 5 without being transferred after the transfer step. The cleaning device 1 is arranged on the downstream side in the rotation direction A of the photosensitive drum 5 with respect to the portion where the photosensitive drum 5 and the transfer belt 6 are in contact with each other. The cleaning device 1 includes a brush roll 11, a charge removal unit 8, a brush roll contact member 13, a cleaning blade 15, an environment detection unit (detection unit) 17, and a voltage switching unit (voltage switching unit) 19. Prepare.

The brush roll 11 is disposed upstream of the cleaning blade 15 in the rotation direction A of the photosensitive drum 5 and removes and holds at least a part of the transfer residual toner. The brush roll 11 has a metal shaft member 11a and a brush portion 11b fixed to the shaft member 11a, and is conductive. The shaft member 11 a extends in the axial direction of the photosensitive drum 5. The brush portion 11b is a base fabric in which a plurality of raised brushes are planted, and is fixed to the shaft member 11a by being wound around the outer peripheral surface of the shaft member 11a. Examples of the material of the brush portion 11b include conductive acrylic, conductive PET, conductive nylon, a thickness of 3 to 6 denier, and a density of 50 to 200K / inch ² . Further, the outer diameter of the brush roll 11 is, for example, 10 to 20 mm in diameter (of which the length of the brushed portion included in the brush portion is 2 to 5 mm), and the resistance value of the brush roll 11 is, for example, 10 ² to 10 ⁶ MΩ. It is.

  Here, the resistance value of the brush roll 11 was measured with an ammeter when, for example, a copper plate, an ammeter, and a power source in which the brush roll 11 was bitten were connected in series and the brush roll 11 was rotated three times. Calculated by the average value. For example, the power source is 500 V, and the brush roll 11 is bitten by 0.5 mm into the copper plate in a novel state without toner adhesion.

  The voltage applied to the brush roll 11 can be switched by the voltage switching unit 19. The voltage switching unit 19 switches the voltage to be applied to the conductive brush roll according to the environmental state of the image forming apparatus 10 and the state of the surface 5a of the photosensitive drum 5 with which the brush roll 11 is in contact. For example, the voltage switching unit 19 switches the voltage applied to the brush roll 11 to the same polarity or the opposite polarity with respect to the polarity of the transfer residual toner on the surface 5 a of the photosensitive drum 5. The voltage switching unit 19 switches off the voltage applied to the brush roll 11. Details of the operation of the brush roll 11 by the voltage switching unit 19 will be described later.

  In the circumferential direction orthogonal to the rotation axis direction of the photosensitive drum 5, at least a part of the brushed brush 11 is in contact with the surface 5 a of the photosensitive drum 5. The brush roll 11 rotates in a direction B that opposes the rotation direction A at a portion in contact with the photosensitive drum 5. Note that the brush roll 11 may rotate in the direction opposite to the direction B. When a positive voltage is applied to the brush roll 11 by the voltage switching unit 19, the brush roll 11 captures the transfer residual toner on the surface of the photosensitive drum 5 by raising the brush. That is, the brush roll 11 removes the transfer residual toner from the surface 5 a of the photosensitive drum 5 and cleans the surface of the photosensitive drum 5. Further, the brush roll 11 holds the transfer residual toner collected from the surface 5 a of the photosensitive drum 5.

  The neutralizing unit 8 is disposed upstream of the brush roll 11 in the rotation direction A of the photosensitive drum 5. The neutralizing unit 8 neutralizes the surface potential of the photosensitive drum 5. As a result, the brush roll 11 comes into contact with the surface 5 a of the photosensitive drum 5 after the surface potential of the photosensitive drum 5 is neutralized by the neutralizing means 8.

  The brush roll contact member 13 is a metal roll member, for example, and extends in the axial direction of the photosensitive drum 5. The width in the extending direction of the brush roll contact member 13 is substantially the same as the width in the extending direction of the brush roll 11, and the brush roll contact member 13 extends over the entire axial direction of the shaft member 11 a of the brush roll 11. Abut (see FIG. 2). The brush roll contact member 13 has a spiral groove 13a formed so as to be wound in one direction. The brush roll contact member 13 rotates so that it can be switched between clockwise and counterclockwise. The brush roll contact member 13 rotates in the same direction or the opposite direction with respect to the rotation direction of the brush roll 11, so that the transfer residual toner held by the brush roll 11 is evenly distributed in the longitudinal direction of the brush roll contact member 13. to recover. Further, the brush roll contact member 13 rotates in the same direction as the rotation direction of the brush roll 11 or in the opposite direction so that the collected transfer residual toner is circulated in the axial direction and applied to the entire area of the brush roll 11 in the axial direction. To do.

  The cleaning blade 15 is a plate-like member and is made of an elastic body such as urethane rubber. The cleaning blade 15 is disposed downstream of the brush roll 11 in the rotation direction A of the photosensitive drum 5, and the transfer residual toner remaining on the surface 5 a of the photosensitive drum 5 is not removed by the brush roll 11. The transfer residual toner is removed. The cleaning blade 15 extends in the axial direction of the photosensitive drum 5. The cleaning blade 15 has a leading edge portion 15 a that abuts the entire area of the photosensitive drum 5 in the axial direction. The width of the cleaning blade 15 in the extending direction and the width of the brush roll 11 in the extending direction are substantially the same. The cleaning blade 15 scrapes off the transfer residual toner remaining on the surface 5a of the photosensitive drum 5 and not removed by the brush roll 11 by the leading edge portion 15a.

  The environment detection unit 17 is an environment sensor that detects the temperature and humidity in the image forming apparatus 10 and detects whether or not the image forming apparatus 10 is in a high-temperature and high-humidity environment. The high temperature and high humidity environment is, for example, a range where the temperature is 28 to 32.5 ° C. and the humidity is 60 to 80% RH, and the standard environment that is not a high temperature and high humidity environment is, for example, a temperature of 10 to 27.9. The temperature is in the range of 20 to 79% RH. The high temperature and high humidity environment and the standard environment are not limited to the exemplified ranges, and can be set as appropriate. The environment detection unit 17 is attached to a location in the image forming apparatus 10 where the temperature is substantially the same as the outside air temperature. For example, it is attached to a position away from a fixing device or a power source as a heat source and without an exhaust fan, that is, a position where the temperature inside the apparatus does not increase. Environmental state information indicating whether or not the image forming apparatus 10 detected by the environment detection unit 17 is in a high temperature and high humidity environment is output to the voltage switching unit 19.

  Next, the operation of the brush roll 11 by the voltage switching unit 19 will be described in detail.

  3 to 5 are timing diagrams illustrating an example of operation timing of the brush roll 11 corresponding to the printing process, and are diagrams illustrating at which timing the brush roll 11 operates in the printing process. The position of the dotted line in the figure indicates a state where the starting power supply of each process is turned off or a state where the applied voltage of the brush roll 11 is turned off. The position above the dotted line indicates that the start-up power supply is turned on in each step, or that the voltage applied to the brush roll 11 has the same polarity as the transfer residual toner on the surface 5a of the photosensitive drum 5. . The lower side of the dotted line indicates that the applied voltage of the brush roll 11 has a polarity opposite to that of the transfer residual toner on the surface 5 a of the photosensitive drum 5.

  As shown in FIGS. 3 to 5, the printing process is performed at the following timing. First, the motor of the photosensitive drum 5 is activated to charge the photosensitive drum 5 with a negative charge (charging process). Subsequently, the surface of the charged photosensitive drum 5 is exposed according to an image formed on the printing paper (exposure process). After the exposure process is completed, toner is supplied from a toner tank provided on the peripheral surface of the photosensitive drum 5 corresponding to each photosensitive drum 5 to develop the electrostatic latent image formed on the photosensitive drum 5 ( Development process). Following the start of the developing process, the toner image formed in this way is primarily transferred from the photosensitive drum 5 to the transfer belt 6 in a region where the photosensitive drum 5 and the transfer belt 6 face each other (transfer process). .

  The voltage switching unit 19 switches the voltage to be applied according to the environmental state information detected by the environment detection unit 17. First, the case where the detected environmental state information is a standard environment that is not a high-temperature and high-humidity environment (in the case of a standard hot-humid environment) will be described. FIG. 3 is a timing chart showing an example of the operation timing of the brush roll 11 under the standard environment. As shown in FIG. 3, in a standard hot and humid environment, the voltage switching unit 19 is configured such that the brush roll 11 contacts the image forming unit of the photosensitive drum 5 or contacts the non-image forming unit of the photosensitive drum 5. The voltage to be applied is switched accordingly. Here, the image forming portion of the photosensitive drum 5 is a portion where the photosensitive drum 5 is exposed and developed in accordance with an image to be formed on printing paper, and is hereinafter simply referred to as an “image forming portion”. The non-image forming portion of the photosensitive drum 5 is a portion where the photosensitive drum 5 does not form an image on printing paper, and is simply referred to as “non-image forming portion” hereinafter. For example, at the time of pre-printing before printing (Cycle UP) and post-printing after printing (Cycle Down), no image is formed on the printing paper in any part of the photoconductive drum 5, so the entire photoconductive drum 5 is used. Becomes a non-image forming portion. Further, during continuous printing, a portion where the photosensitive drum 5 is not exposed and developed between the image forming portions (that is, between the papers on which the paper is not placed on the transfer belt 6) is not formed. Part.

  When the conductive brush roll comes into contact with the non-image forming portion of the photosensitive drum 5, the voltage switching portion 19 turns off the voltage applied to the brush roll 11. As a result, neither the transfer residual toner is collected nor discharged. The transfer residual toner is not collected when the surface 5a of the photosensitive drum 5 is a non-image forming portion between the surface 5a of the photosensitive drum 5 and the leading edge 15a of the cleaning blade 15. This is because there is no transfer residual toner. The untransferred toner is not discharged because, even if the surface 5a of the photosensitive drum 5 is a non-image forming compatible portion, the image forming apparatus 10 is not in a high temperature and high humidity environment. This is because the coefficient of dynamic friction between the surface 5a and the tip edge portion 15a of the cleaning blade 15 is small and the cleaning blade 15 itself is hard, so that there is almost no fear of the cleaning blade 15 being swung.

  On the other hand, when the conductive brush roll comes into contact with the image forming portion of the photosensitive drum 5, the voltage applied to the brush roll 11 is switched to a polarity opposite to the transfer residual toner on the surface 5 a of the photosensitive drum 5. Thereby, a part of the transfer residual toner is collected and held by the brush roll 11 from the surface 5 a of the photosensitive drum 5. At this time, the transfer residual toner collected on the brush roll 11 becomes a transfer residual toner for discharging to the surface 5a of the photosensitive drum 5.

  Next, a case where the detected environmental state information is a high temperature and high humidity environment will be described. FIG. 4 is a timing chart showing an example of the operation timing of the brush roll 11 in a high-temperature and high-humidity environment and the image forming unit has a normal image density. FIG. 5 is a timing diagram illustrating an example of the operation timing of the brush roll 11 in a high temperature and high humidity environment where the image forming unit has a low image density. Here, the normal image density of the image forming unit means, for example, the area ratio of the exposed and developed portion (image portion) of the photosensitive drum 5 to the area of the entire printing paper (hereinafter simply referred to as “image density”). ) Is higher than a predetermined image density. The image forming unit having a low image density means, for example, a case where the image density is at least a predetermined image density or less. The predetermined image density is, for example, 5% when the A4 size printing paper is laterally fed in the image forming apparatus 10 having the maximum paper size of A3. Further, since the occurrence of blade curling is likely to start when the density is lower, the predetermined image density may be set to a value of less than 5%. Note that the predetermined image density may be 10% when the A5 size printing paper is horizontally fed, and the predetermined image density may be 20% when the A6 size printing paper is horizontally fed. As described above, the predetermined image density can be appropriately set according to the size of the printing paper.

  As shown in FIGS. 4 and 5, when the surface 5 a of the photosensitive drum 5 in contact with the brush roll 11 is a non-image forming unit, the voltage switching unit 19 has the same polarity as the transfer residual toner on the photosensitive drum 5. A negative voltage is applied to the brush roll 11. As a result, electrical repulsion occurs between the transfer residual toner and the brush roll 11, and the transfer residual toner is discharged from the brush roll 11 to the surface 5 a of the photosensitive drum 5. This is because when the image forming apparatus 10 is in a high temperature and high humidity environment and the surface 5a of the photosensitive drum 5 is a non-image forming portion, the surface 5a of the photosensitive drum 5 and the leading edge 15a of the cleaning blade 15 are used. This is because the coefficient of dynamic friction between the cleaning blade 15 and the cleaning blade 15 itself becomes soft, and the cleaning blade 15 is likely to bend.

  On the other hand, when the surface 5a of the photosensitive drum 5 in contact with the brush roll 11 is an image forming unit, the voltage switching unit 19 switches the applied voltage as follows according to the image density of the image forming unit.

  As shown in FIG. 4, when the image forming unit has the normal image density, the voltage switching unit 19 applies a positive voltage having a polarity opposite to the transfer residual toner on the surface 5 a of the photosensitive drum 5 to the brush roll 11. Apply. As a result, electrical attraction occurs between the transfer residual toner and the brush roll 11, and a part of the transfer residual toner on the surface 5 a of the photosensitive drum 5 is collected on the brush roll 11. This is because when the image forming portion has a normal image density, there is sufficient transfer residual toner between the surface 5a of the photosensitive drum 5 and the leading edge portion 15a of the cleaning blade 15, and there is sufficient transfer residual toner. This is because the cleaning blade 15 is less likely to sag than in the case of a low image density that does not exist in FIG. At this time, the transfer residual toner collected on the brush roll 11 becomes a transfer residual toner for discharging to the surface 5a of the photosensitive drum 5.

  On the other hand, as shown in FIG. 5, when the image forming unit is a low image density unit, the voltage switching unit 19 applies a negative voltage having the same polarity as the transfer residual toner on the surface 5a of the photosensitive drum 5. And applied to the brush roll 11. As a result, electrical repulsion occurs between the transfer residual toner and the brush roll 11, and the transfer residual toner is discharged from the brush roll 11 to the surface 5 a of the photosensitive drum 5. This is because when the image forming portion has a low image density, there is not enough transfer residual toner between the surface 5a of the photosensitive drum 5 and the leading edge portion 15a of the cleaning blade 15, and there is sufficient transfer residual toner. This is because the cleaning blade 15 is more likely to bend than in the case of the existing normal image density.

As described above, in a high-temperature and high-humidity environment, when the conductive brush roll is in contact with the image forming portion of the photosensitive drum 5 and the image forming portion has a low image density, or non-image formation of the photosensitive drum 5 When the conductive brush roll comes into contact with the portion, the transfer residual toner is discharged from the brush roll 11 to the surface 5 a of the photosensitive drum 5. At this time, the amount of the toner including the transfer residual toner discharged to the surface 5a of the photosensitive drum 5 is preferably 3 × 10 ⁻⁷ g / cm ² or more, and 1.0 × 10 ⁻⁷ g / cm ^2. It is still more preferable that it is above. The toner for discharging is a brush from the surface 5a of the photosensitive drum 5 when the image forming unit has a normal image density in a high temperature and high humidity environment or in a standard environment other than the high temperature and high humidity environment. The residual toner collected on the roll 11 can be used, but is not limited thereto. For example, in order to maintain the characteristics of the developer, toner that is periodically developed using a toner band image having the maximum paper width as a toner drain, and collected and held by the brush roll 11 may be used.

  Next, the appropriate values of the resistance and applied voltage of the brush roll 11 in terms of cleaning performance and discharge performance will be described with reference to FIGS. 6 and 7. 6 and 7, the horizontal axis indicates the voltage applied to the conductive brush roll, and the vertical axis indicates the resistance of the brush roll 11.

First, a case where a voltage having a polarity opposite to that of the transfer residual toner is applied to the brush roll 11 will be described. FIG. 6 is a graph showing an appropriate value of the resistance and applied voltage of the brush roll 11 when a voltage having a polarity opposite to that of the transfer residual toner is applied. For example, when the polarity of the transfer residual toner on the surface 5 a of the photosensitive drum 5 is negative, when a positive voltage having the opposite polarity is applied to the brush roll 11, the transfer residual toner is transferred to the photosensitive drum by the brush roll 11. 5 is removed from the surface 5a (hereinafter also simply referred to as “cleaning”). At this time, if the resistance value is 10 ² MΩ or less, a short circuit occurs between the photosensitive drums 5 due to the voltage application, and the voltage cannot be maintained. On the other hand, if the resistance value is 10 ⁶ MΩ or more, the remaining transfer toner cannot be cleaned and discharged to the photosensitive drum 5 due to the voltage drop. Therefore, when viewed from the viewpoint of cleaning performance and discharge performance, the resistance value is preferably in a range larger than 10 ² MΩ and smaller than 10 ⁶ MΩ.

  When the applied voltage of the brush roll 11 is +100 V or less, the transfer residual toner cannot be electrostatically adsorbed and cleaning cannot be performed. On the other hand, at the discharge start voltage (+700 V) or higher, the transfer residual toner can be retained by cleaning, but the retained transfer residual toner is reversed. Therefore, when the same polarity as that of the transfer residual toner is applied, the brush roll 11 Therefore, the transfer residual toner cannot be discharged to the photosensitive drum 5. Therefore, when viewed from the viewpoint of the cleaning performance and the discharge performance, the applied voltage of the brush roll 11 is preferably in a range larger than + 100V and smaller than + 700V.

Next, a case where a voltage having the same polarity as the untransferred toner is applied to the brush roll 11 will be described. FIG. 7 is a graph showing the resistance of the brush roll 11 and the appropriate values of the applied voltage when a voltage having the same polarity as the transfer residual toner is applied. For example, if the polarity of the transfer residual toner on the surface 5a of the photosensitive drum 5 is negative, applying a negative voltage having the same polarity to the brush roll 11 causes the transfer residual toner held on the conductive brush roll to be removed. It is discharged to the photosensitive drum 5 (hereinafter also simply referred to as “discharge”). At this time, for the same reason as when a voltage having a polarity opposite to that of the transfer residual toner is applied to the brush roll 11, the resistance value is preferably in a range larger than 10 ² MΩ and smaller than 10 ⁶ .

  When the applied voltage of the brush roll 11 is −100 V or more, the transfer residual toner cannot be electrostatically repelled on the brush roll 11 and cannot be discharged. On the other hand, at the discharge start voltage (−700 V) or less, the transfer residual toner on the photosensitive drum 5 is overcharged, and charge is transferred to and from the transfer residual toner held on the brush roll 11. As a result, the polarity of the toner remaining after transfer is mixed, and the discharge becomes unstable. Therefore, when viewed from the viewpoint of cleaning performance and discharge performance, the applied voltage of the brush roll 11 is preferably in a range larger than −700V and smaller than −100V.

  From the above, it is preferable that the absolute value of the voltage applied to the brush roll 11 is larger than 100 V and smaller than the discharge start voltage.

  Next, an example of operation | movement of the brush roll 11 in the said appropriate range is demonstrated using FIG. FIG. 8 is a graph showing an example of the operation of the brush roll 11 with respect to the number of printed sheets. The horizontal axis in FIG. 8 indicates the number of printed sheets, and the vertical axis in FIG. 8 indicates the toner holding amount of the brush roll 11 or the voltage applied to the brush roll 11. The straight line a in the graph of FIG. 8 shows the displacement of the applied voltage to the brush roll 11 as the number of printed sheets increases, and the straight line b in the graph of FIG. 8 indicates the toner holding amount of the brush roll 11 as the number of printed sheets increases. The displacement is shown.

  As shown in FIG. 8, in a standard environment other than a high-temperature and high-humidity environment, the brush roll 11 has only a toner recovery mode for all images regardless of whether it is an image forming unit or a non-image forming unit. Become. In this mode, for example, a voltage of 500 V having a polarity opposite to the transfer residual toner is applied to the brush roll 11.

  On the other hand, when the brush roll 11 is an image forming unit or a non-image forming unit in a high temperature and high humidity environment, the toner discharge mode and the toner recovery mode are mixed (when the image forming unit has a normal image density). ) And only the discharge mode for all images regardless of whether it is an image forming unit or a non-image forming unit (when the image forming unit has a low image density). When the toner discharge mode and the toner recovery mode coexist, for example, the applied voltage can be displaced within a range indicated by vertical stripes in FIG. For example, in the toner discharge mode, −200 V having the same polarity as the residual transfer toner is applied to the brush roll 11, and in the toner recovery mode, 500 V having the opposite polarity to the residual transfer toner is applied to the brush roll 11. When only the toner discharge mode is selected, for example, −200 V having the same polarity as that of the transfer residual toner is applied to the brush roll 11. A small amount of transfer residual toner of 25 g is discharged.

  As described above, according to the cleaning device 1 according to the present embodiment, the cleaning blade 1 is held by the brush roll 11 due to electric repulsion when the cleaning blade is in a high-temperature and high-humidity environment and a non-image forming portion that is relatively easy to bend. The remaining transfer residual toner is discharged onto the surface 5a of the photosensitive drum 5 to improve the lubricity. By discharging the toner to the photosensitive drum 5 at the most necessary timing in this manner, unnecessary toner discharge is eliminated, and a certain amount of toner is discharged, and the cleaning blade 15 is appropriately prevented from curling. be able to.

  Further, according to the cleaning device 1, even when the environment detection unit 17 detects that the image forming apparatus 10 is in a high-temperature and high-humidity environment, the image density of the image forming unit of the photosensitive drum 5, that is, the transfer residual Depending on the amount of toner, the toner can be discharged or the toner can be collected. As a result, toner can be supplied when the cleaning blade 15 is likely to curl, while the cleaning blade 15 can collect the toner when the cleaning blade 15 is difficult to curl. However, the cleaning blade 15 can be appropriately prevented from turning.

  Further, according to the cleaning device 1, when the image forming unit is a normal image density unit having a density higher than a predetermined image density, the transfer residual toner can be collected and held by the brush roll 11 by electrical attraction. it can. As a result, the collected and retained transfer residual toner can be used for discharging to the surface 5 a of the photosensitive drum 5. On the other hand, when the image forming portion is a low image density portion having a predetermined image density or less, the transfer residual toner held on the brush roll 11 can be discharged to the surface 5 a of the photosensitive drum 5 by electric repulsion. . As a result, it is possible to appropriately improve the lubricity between the surface 5a of the photosensitive drum 5 and the tip edge portion 15a of the cleaning blade 15.

  The predetermined image density is, for example, an image density of 5% when A4 size printing paper is used. Further, since the occurrence of blade curling is likely to start when the density is lower, the predetermined image density may be set to a value of less than 5%.

  Further, according to the cleaning device 1, under the standard environment, when the brush roll 11 is in contact with the image forming portion of the photosensitive drum 5, the transfer residual toner is collected and held by the brush roll 11. As a result, the collected and retained transfer residual toner can be used for discharging to the surface 5 a of the photosensitive drum 5. Further, when the brush roll 11 is in contact with the non-image forming portion of the photosensitive drum 5 under a standard environment, no voltage is applied to the brush roll 11. Therefore, in the case of a standard environment where the cleaning blade 15 is less likely to bend than in a high temperature and high humidity environment, the transfer residual toner is not discharged even when the brush roll 11 is in contact with the non-image forming portion. Useless transfer residual toner can be prevented from being discharged.

  Further, according to the cleaning device 1, the transfer residual toner is collected from the brush roll 11 by the brush roll contact member 13 and the collected transfer residual toner is applied to the brush roll 11, so that it is held by the brush roll 11. The bias of the transfer residual toner can be suppressed.

  The brush roll contact member 13 is in contact with the entire area of the brush roll 11 in the axial direction and has a spiral groove 13a wound in one direction. The rotation direction of the brush roll contact member 13 is clockwise and counterclockwise. It has been switched to one of the surroundings. In a state where the brush roll contact member 13 having such a spiral groove 13a is in contact with the entire axial direction of the brush roll 11, the brush roll contact member 13 is switched to rotate clockwise or counterclockwise to rotate. Therefore, the transfer residual toner can be uniformly applied to the entire axial direction of the conductive brush roll.

Further, the resistance value of the brush roll 11 is larger than 10 ² MΩ and smaller than 10 ⁶ MΩ, and the absolute value of the voltage applied to the brush roll 11 is larger than 100 V and smaller than the discharge start voltage. These ranges are preferable from the viewpoint of the cleaning performance and discharge performance of the brush roll 11.

Further, the amount of toner including the transfer residual toner discharged to the surface 5a of the photosensitive drum 5 is preferably 3 × 10 ⁻⁷ g / cm ² or more, and 1.0 × 10 ⁻⁷ g / cm ² or more. More preferably.

  For example, in the case of a high-temperature and high-humidity environment and a non-image forming portion, a surface potential of about −600 V remains on the photosensitive drum 5 unless neutralization is performed, and a voltage of about −200 V is applied to the brush roll 11 in this state. Even in this case, the transfer residual toner may not be discharged well. According to the present embodiment, since the surface potential of the photosensitive drum 5 is neutralized by the neutralization unit 8, the transfer residual toner from the brush roll 11 can be discharged appropriately.

  Here, a modified example of the cleaning device 1 according to the present embodiment will be described with reference to FIG. FIG. 9 is a schematic configuration diagram of the cleaning device according to the modification viewed from the circumferential direction of the photosensitive drum.

  As shown in FIG. 9, the cleaning device 1 </ b> A according to the modification differs from the cleaning device 1 according to the above embodiment in that the brush roll contact member 23 includes the first spiral groove 23 a wound in one direction and the other direction. The second spiral groove 23b is wound around and the rotation direction of the brush roll contact member 23 is either clockwise or counterclockwise.

  The first spiral groove 23a is formed in a range extending from one end region 23B to the central region 23A in the longitudinal direction of the brush roll contact member 23. The second spiral groove 23b is formed in a range extending from the other end region 23C to the central region 23A in the longitudinal direction of the brush roll contact member 23. Therefore, in the central region 23A, the first spiral groove 23a and the second spiral groove 23b wound in different directions are mixed. Thereby, even if the rotation direction of the brush roll contact member 23 is either clockwise or counterclockwise, the transfer residual toner can be circulated in the axial direction.

  Further, a first spiral groove 23a wound in one direction is formed in the end region 23B, and a second spiral groove 23b wound in the other direction is formed in the end region 23C. That is, the end region 23B and the end region 23C are formed with spiral grooves in different directions. Thereby, even if the rotation direction of the brush roll contact member 23 is either clockwise or counterclockwise, the transfer residual toner can be conveyed to both ends in the longitudinal direction of the brush roll 11. As described above, the transfer residual toner can be uniformly applied to the entire area of the brush roll 11 in the axial direction by the brush roll contact member 23.

  The preferred embodiments of the present embodiment have been described above. However, the present invention is not limited to the above-described embodiments. The present invention is not limited to the gist described in each claim and can be modified or applied to others. It may be what you did.

  For example, regardless of whether or not the environment detection unit 17 detects that the image forming apparatus 10 is in a high temperature and high humidity environment, when the brush roll 11 is in contact with the image forming unit of the photosensitive drum 5, When the image forming unit has a normal image density, a voltage having a polarity opposite to that of the remaining transfer residual toner is applied to the brush roll 11, and when the image forming unit has a low image density, the voltage having the same polarity as the remaining transfer residual toner is applied. A voltage may be applied to the brush roll 11. Also by this, the brush roll 11 is in contact with the image forming portion of the photosensitive drum 5, and when the image forming portion is a normal image density portion, the transfer residual toner is collected and held by the brush roll 11. The collected and retained transfer residual toner is discharged to the surface 5a of the photosensitive drum 5 when the brush roll 11 is in contact with the image forming portion of the photosensitive drum 5 and the image forming portion is a low image density portion. It is. As a result, the lubricity between the surface 5a of the photosensitive drum 5 and the tip edge portion 15a of the cleaning blade 15 can be improved. As described above, by discharging toner to the photosensitive drum 5 at the most necessary timing, unnecessary toner discharge is eliminated and a certain amount of toner for discharge is secured, and the cleaning blade 15 is appropriately prevented from curling. be able to. The “low image density” and “normal image density” used here are the same as those used in the above-described embodiment.

  In this embodiment, the transfer residual toner is negative. However, the transfer residual toner may be positive. In this case, the same polarity of the transfer residual toner is positive and the transfer residual toner is positive. The reverse polarity of the remaining toner is negative.

  DESCRIPTION OF SYMBOLS 1,1A ... Cleaning apparatus, 5 ... Photosensitive drum (image carrier), 5a ... Surface, 8 ... Static elimination means, 10 ... Image forming apparatus, 11 ... Brush roll (conductive brush roll), 13, 23 ... Brush roll Contact member, 13a ... spiral groove, 23a ... first spiral groove, 23b ... second spiral groove, 15 ... cleaning blade, 17 ... environment detection unit, 19 ... voltage switching unit.

Claims (12)

A cleaning device that removes transfer residual toner remaining on the surface of an image carrier in an image forming apparatus,
A conductive brush roll that contacts the surface of the image carrier and removes and retains at least a portion of the transfer residual toner;
A charge removing unit disposed on the upstream side of the conductive brush roll in the rotation direction of the image carrier, and neutralizing the surface potential of the image carrier;
A cleaning blade that contacts the surface of the image carrier and removes the transfer residual toner that has not been removed by the conductive brush roll among the residual transfer residual toner;
Detecting means for detecting whether or not the image forming apparatus is in a high temperature and high humidity environment;
Voltage switching means for switching the application of voltage to the conductive brush roll,
The voltage switching means is
When the detection unit detects that the image forming apparatus is in a high-temperature and high-humidity environment, when the conductive brush roll comes into contact with the non-image forming portion of the image carrier, it is the same as the remaining transfer residual toner. When a voltage having a polarity is applied to the conductive brush roll and the conductive brush roll is in contact with the image forming portion of the image carrier, the residual transfer residual toner and the residual toner according to the image density of the image forming portion A cleaning device that applies a reverse polarity voltage or a voltage having the same polarity as the remaining transfer residual toner to the conductive brush roll . The voltage switching means is
When the image forming unit has a normal image density higher than a predetermined image density, a voltage having a polarity opposite to that of the remaining transfer residual toner is applied to the conductive brush roll, and the image forming unit 2. The cleaning device according to claim 1 , wherein a voltage having the same polarity as the remaining transfer residual toner is applied to the conductive brush roll when the image density is lower than the image density. The cleaning apparatus according to claim 2 , wherein the predetermined image density is such that an area ratio of an image portion to an entire area of the printing paper is 5% when A4 size printing paper is used. The voltage switching means is
When the image forming apparatus is detected as a standard environment that is not a high-temperature and high-humidity environment by the detecting means, when the conductive brush roll is in contact with a non-image forming portion of the image carrier, a voltage is applied to the conductive brush. not applied to the roll, when said conductive brush roller is in contact applies a transfer residual toner and opposite polarity voltage the residual to the conductive brush roller in the image forming portion of the image bearing member, according to claim 1 to 3 The cleaning device according to any one of the above. A brush roll contact that contacts the conductive brush roll, collects the transfer residual toner held by the conductive brush roll from the conductive brush roll, and applies the recovered transfer residual toner to the conductive brush roll. The cleaning device according to any one of claims 1 to 4 , further comprising a member. The brush roll contact member is in contact with the entire axial direction of the conductive brush roll, and has a spiral groove wound in one direction,
The cleaning device according to claim 5 , wherein the rotation direction of the brush roll contact member is switched between a clockwise direction and a counterclockwise direction. The brush roll contact member is in contact with the entire region of the conductive brush roll in the axial direction, and has a first spiral groove wound in one direction and a second spiral groove wound in the other direction,
The cleaning device according to claim 5 , wherein a rotation direction of the brush roll contact member is one of clockwise rotation and counterclockwise rotation. The resistance value of the conductive brush roll is larger than 10 ² MΩ and smaller than 10 ⁶ MΩ, and the absolute value of the voltage applied to the conductive brush roll is larger than 100 V and smaller than a discharge start voltage. The cleaning device according to any one of 1 to 7 . The amount of the toner containing the residual toner is discharged to the surface of the image bearing member is 1.0 × 10 -7 ^{g /} cm ² or more, the cleaning device according to any one of claims 1-8 . A cleaning device that removes transfer residual toner remaining on the surface of an image carrier in an image forming apparatus,
A conductive brush roll that contacts the surface of the image carrier and removes and retains at least a portion of the transfer residual toner;
A charge removing unit disposed on the upstream side of the conductive brush roll in the rotation direction of the image carrier, and neutralizing the surface potential of the image carrier;
A cleaning blade that contacts the surface of the image carrier and removes the transfer residual toner that has not been removed by the conductive brush roll among the residual transfer residual toner;
Detecting means for detecting whether or not the image forming apparatus is in a high temperature and high humidity environment;
Voltage switching means for switching the application of voltage to the conductive brush roll,
The voltage switching means is
When the detection unit detects that the image forming apparatus is in a high-temperature and high-humidity environment, when the conductive brush roll comes into contact with the non-image forming portion of the image carrier, it is the same as the remaining transfer residual toner. When a voltage of polarity is applied to the conductive brush roll and the image forming apparatus is detected as a standard environment that is not a high-temperature and high-humidity environment by the detecting means, the conductive property is applied to the non-image forming portion of the image carrier. When the brush roll comes into contact, no voltage is applied to the conductive brush roll, and when the conductive brush roll comes into contact with the image forming portion of the image carrier, a voltage having a polarity opposite to that of the remaining transfer residual toner is used. A cleaning device applied to the conductive brush roll. A cleaning device that removes transfer residual toner remaining on the surface of an image carrier in an image forming apparatus,
A conductive brush roll that contacts the surface of the image carrier and removes and retains at least a portion of the transfer residual toner;
A charge removing unit disposed on the upstream side of the conductive brush roll in the rotation direction of the image carrier, and neutralizing the surface potential of the image carrier;
A cleaning blade that contacts the surface of the image carrier and removes the transfer residual toner that has not been removed by the conductive brush roll among the residual transfer residual toner;
Detecting means for detecting whether or not the image forming apparatus is in a high temperature and high humidity environment;
Voltage switching means for switching the application of voltage to the conductive brush roll;
A brush roll contact that contacts the conductive brush roll, collects the transfer residual toner held by the conductive brush roll from the conductive brush roll, and applies the recovered transfer residual toner to the conductive brush roll. A member, and
The voltage switching means is
When the detection unit detects that the image forming apparatus is in a high-temperature and high-humidity environment, when the conductive brush roll comes into contact with the non-image forming portion of the image carrier, it is the same as the remaining transfer residual toner. Apply a polarity voltage to the conductive brush roll,
The brush roll contact member is in contact with the entire axial direction of the conductive brush roll, and has a spiral groove wound in one direction,
The cleaning device, wherein the rotation direction of the brush roll contact member is switched between clockwise and counterclockwise. A cleaning device that removes transfer residual toner remaining on the surface of an image carrier in an image forming apparatus,
A conductive brush roll that contacts the surface of the image carrier and removes and retains at least a portion of the transfer residual toner;
A charge removing unit disposed on the upstream side of the conductive brush roll in the rotation direction of the image carrier, and neutralizing the surface potential of the image carrier;
A cleaning blade that contacts the surface of the image carrier and removes the transfer residual toner that has not been removed by the conductive brush roll among the residual transfer residual toner;
Voltage switching means for switching the application of voltage to the conductive brush roll;
A brush roll contact that contacts the conductive brush roll, collects the transfer residual toner held by the conductive brush roll from the conductive brush roll, and applies the recovered transfer residual toner to the conductive brush roll. A member, and
In the case where the conductive brush roll is in contact with the image forming portion of the image carrier, the voltage switching means remains when the image forming portion has a normal image density higher than a predetermined image density. When a voltage having a polarity opposite to that of the transfer residual toner is applied to the conductive brush roll and the image forming unit has a low image density equal to or lower than the predetermined image density, a voltage having the same polarity as that of the remaining transfer residual toner is applied. Applying to the conductive brush roll,
The brush roll contact member is in contact with the entire axial direction of the conductive brush roll, and has a spiral groove wound in one direction,
The cleaning device, wherein the rotation direction of the brush roll contact member is switched between clockwise and counterclockwise .

Images