JP2007155956A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device capable of removing toner stuck on a rotating brush for cleaning a photoreceptor drum, without having to apply pressured stress to the toner, and maintaining stable detoning performance over a long period of time. <P>SOLUTION: The cleaning apparatus 50 includes a toner deposition roll 52, arranged facing the photoreceptor drum 12, a toner peeling roll 54 arranged away from the photoreceptor drum 12, and the belt-like brush member 56 suspended in between the toner deposition roll 52 and the toner peeling roll 54. The brush member 56 is constituted, by planting many brush fibers 60 on the surface of an endless belt-like base body 58, and the brush member 56 moves around in a fixed direction, while coming into contact with the photoreceptor drum 12. A voltage whose polarity is reverse to that of the toner is applied by a power source 68 on the toner deposition roll 52, and a voltage whose polarity is the same as that of the toner is applied by a power source 66 on the toner peeling roller 54. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning device and an image forming apparatus for cleaning transfer residual toner and the like adhering to the surface of an image carrier such as a photoreceptor or an intermediate transfer member on which a toner image is carried.

  An electrophotographic image forming apparatus is provided with a cleaning device that cleans transfer residual toner, external additives, and the like remaining on the surface of a photoconductor, an intermediate transfer body, and the like after transfer of a toner image.

  As this cleaning device, for example, a configuration is known in which a brush is brought into contact with the surface of a photosensitive drum, and a toner having a polarity opposite to that of the toner is applied to the brush to attract and electrostatically collect the toner. In this configuration, it is necessary to perform so-called detoning, in which the toner attracted to the brush is further collected from the brush. If this detoning function does not work sufficiently, the toner will accumulate in the brush and the recovery efficiency will deteriorate, resulting in insufficient cleaning performance and the cause of toner filming on the photoreceptor. It becomes.

  In such a configuration for detoning the toner on the brush, the toner is collected from the brush by contacting a collecting roll to which a bias having a polarity opposite to that of the toner is applied, and a scraper is brought into contact with the surface from the collecting roll. What is mechanically scraped off is disclosed (for example, see Patent Document 1 and Patent Document 2).

  However, in the configurations of Patent Documents 1 and 2, there is a problem that filming is generated on the collecting roll due to the pressure stress applied to the toner when the scraper contacts the collecting roll, and the detoning capability is gradually insufficient. There is. This problem occurs remarkably when a low-melting toner intended for fixing at a low temperature is used.

  As another configuration, a method is known in which a brush is struck against a bar called a flicker bar to drop toner and remove directly from the brush. However, in this method, since the toner is merely mechanically wiped off by the flicker bar, when toner having a small particle diameter is used, it is difficult to obtain sufficient detoning performance due to insufficient centrifugal force due to light weight.

  As another configuration, the rotating brush is divided into a plurality of electrode segments so as to be rotatable. When collecting toner from the photosensitive member, a voltage having a polarity opposite to that of the toner is applied and the rotating brush adheres to the rotating brush. In order to remove the toner that has been removed, a device that applies a voltage having the same polarity as the toner is disclosed (see, for example, Patent Document 3). In the configuration of Patent Document 3, the detoning effect can be improved by using an electrostatic force when removing the toner.

  However, in the configuration of Patent Document 3, the brush material of the rotating brush generally uses a material adjusted to a medium resistance in order to have conductive electrical characteristics, and delays the potential fluctuation at the tip of the brush. (Delay) occurs. In particular, when outputting at high speed, the nip time between the brush and the photoconductor is short and the amount of toner conveyed to the nip is large. Therefore, the toner is stabilized by the potential fluctuation delay at the tip of the brush. Cannot be recovered. For this reason, there is a problem that sufficient detoning performance cannot be obtained.

  In addition, brush fibers are provided on an endless belt suspended by a plurality of rolls, and one end of the brush fibers is brought into contact with the photoconductor to clean the photoconductor, and then a collection roll is applied to the brush fibers on the belt. A device that contacts and collects toner is disclosed (for example, see Patent Document 4).

However, in the configuration of Patent Document 4, similarly to Patent Document 3, a delay occurs in potential fluctuation at the tip of the brush fiber, and sufficient detoning performance cannot be obtained.
JP-A-57-78579 JP-A-62-168187 JP-A-57-82356 JP 2001-109345 A

  The present invention has been made in view of the above problems, and a cleaning device that suppresses the occurrence of a delay in potential fluctuation at the tip of a brush fiber and maintains stable detoning performance over a long period of time. An object is to provide an image forming apparatus.

  In order to solve the above problems, the cleaning device according to the first aspect of the present invention is disposed so as to contact an image carrier on which a toner image is carried, and cleans the toner from the image carrier. A toner adhering roll having a polarity opposite to that of the toner and rotatably supported at a position spaced apart from the image carrier, and a toner having the same polarity as the toner. A peeling roll, and a belt-like brush member that is suspended from the toner adhesion roll and the toner peeling roll and moves around in contact with the image carrier.

  According to the first aspect of the present invention, the belt-like brush member is suspended from the toner adhering roll and the toner peeling roll, and the brush member moves around in contact with the image carrier. A toner adhesion roll having a polarity opposite to that of the toner is supported facing the image carrier, and the toner is electrostatically attracted to the brush member from the image carrier. The toner adhering to the brush member moves to the position of the toner peeling roll by the circular movement of the brush member. The toner peeling roll has the same polarity as the toner, and a repulsive force acts on the toner, so that the toner is removed from the brush member. As a result, the toner is removed from the brush member without applying stress to the toner, and filming is unlikely to occur in the brush member even when a low melting point toner is used. In addition, since the toner adhesion roll for suspending the brush member has a polarity opposite to that of the toner and the toner removal roll has the same polarity as that of the toner, occurrence of a delay in the potential fluctuation at the tip of the brush member is suppressed. The For this reason, it is possible to stably collect the toner from the image carrier onto the brush member and remove the toner adhering to the brush member, and a stable detoning performance can be obtained over a long period of time.

  According to a second aspect of the present invention, in the cleaning device according to the first aspect, a fixed electrode having the same polarity as the toner contacting the back surface of the brush member is provided immediately before the position where the toner is peeled from the brush member. It is characterized by being.

  According to the second aspect of the present invention, the fixed electrode having the same polarity as the toner is brought into contact with the back surface of the brush member immediately before the position where the toner is peeled off from the brush member. The influence of the electrical characteristic delay at the tip of the brush member is small. For this reason, even when outputting at high speed, the occurrence of defective cleaning is suppressed.

  According to a third aspect of the present invention, in the cleaning device according to the first or second aspect, a flicker member that contacts the brush fibers of the brush member is provided at a position where the toner is peeled off from the brush member. It is characterized by that.

  According to the third aspect of the present invention, since the flicker member is brought into contact with the brush fibers of the brush member, the toner attached to the brush fibers of the brush member can be removed.

  According to a fourth aspect of the present invention, an image forming apparatus includes the cleaning device according to any one of the first to third aspects.

  According to the fourth aspect of the present invention, the toner adhering to the brush member is removed without applying stress to the toner, and filming is unlikely to occur in the brush member even when a low melting point toner is used. In addition, since the toner adhesion roll for suspending the brush member has a polarity opposite to that of the toner and the toner peeling roll has the same polarity as that of the toner, the occurrence of a delay in the potential fluctuation at the tip of the brush member is suppressed. Stable detoning performance can be obtained over a long period of time.

  In the cleaning device and the image forming apparatus according to the present invention, it is possible to suppress the occurrence of a delay in the potential fluctuation at the tip of the brush member, and it is possible to stably remove the toner attached to the brush member. For this reason, stable detoning performance can be maintained over a long period of time.

  Hereinafter, embodiments of a cleaning device and an image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 shows an image forming apparatus 100 including a cleaning device 50 according to the first embodiment of the present invention.

  The image forming apparatus 100 performs image processing based on color image information sent from an image data input device such as a personal computer (not shown), and forms a color image on a recording sheet P by an electrophotographic method.

  The image forming apparatus 100 includes image forming units 10Y, 10M, 10C, and 10K that form toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K). In the following, when it is necessary to distinguish YMCK, description will be made by adding any of Y, M, C, and K after the reference. When YMCK does not need to be distinguished, Y, M, C, K is omitted.

  The image forming units 10Y, 10M, 10C, and 10K are arranged so that the image forming units 10Y, 10M, 10C, and 10K move in the traveling direction of the endless intermediate transfer belt 30 that is stretched by the backup roll 34 and the plurality of stretch rolls 32. They are arranged in series in the order of 10K. Further, the intermediate transfer belt 30 is provided with primary transfer rolls 16Y, which are arranged to face the photosensitive drums 12Y, 12M, 12C, and 12K as image carriers of the image forming units 10Y, 10M, 10C, and 10K, respectively. It is inserted between 16M, 16C and 16K.

  Next, the configuration of each of the image forming units 10Y, 10M, 10C, and 10K and the image forming operation will be described using the image forming unit 10Y that forms a yellow toner image as a representative.

  The surface of the photosensitive drum 12Y is uniformly charged by the contact charger 13Y. Next, image exposure corresponding to the yellow image is performed by the exposure device 14Y, and an electrostatic latent image corresponding to the yellow image is formed on the surface of the photosensitive drum 12Y.

  The electrostatic latent image corresponding to the yellow image is developed by the toner carried on the developing roll 18Y to which the developing bias of the developing device 15Y is applied, and becomes a yellow toner image. The yellow toner image is primarily transferred onto the intermediate transfer belt 30 by the pressing force of the primary transfer roll 16Y and the electrostatic attraction force by the transfer bias applied to the primary transfer roll 16Y.

  In this primary transfer, the entire yellow toner image is not transferred to the intermediate transfer belt 30, and a part of the yellow toner image remains on the photosensitive drum 12Y as transfer residual yellow toner. Further, an external additive of toner is also attached to the surface of the photosensitive drum 12Y. After the primary transfer, the photosensitive drum 12Y passes through a position facing the cleaning device 50Y, and transfer residual toner and the like on the surface of the photosensitive drum 12Y are removed. Details of the cleaning device 50Y will be described later.

  Thereafter, the surface of the photosensitive drum 12Y is charged again by the contact charger 13Y for the next image forming cycle.

  As shown in FIG. 1, in the image forming apparatus 100, the image forming process similar to the above is performed at each image forming unit 10Y at a timing in consideration of the relative position difference between the image forming units 10Y, 10M, 10C, and 10K. , 10M, 10C, and 10K, and Y, M, C, and K color toner images are sequentially superimposed on the intermediate transfer belt 30 to form a multiple toner image.

  Then, the multiple toner images are batched from the intermediate transfer belt 30 by the electrostatic attraction force of the secondary transfer roll 36 to which the transfer bias is applied to the recording paper P conveyed to the secondary transfer position A at a predetermined timing. Then, it is transferred onto the recording paper P.

  The recording paper P to which the multiple toner images have been transferred is separated from the intermediate transfer belt 30, and then conveyed to the fixing device 31, where it is fixed to the recording paper P by heat and pressure, thereby forming a full color image.

  The transfer residual toner on the intermediate transfer belt 30 that has not been transferred to the recording paper P is collected by the intermediate transfer belt cleaner 33.

  Next, the cleaning device 50 will be described.

  As shown in FIG. 2, the cleaning device 50 includes a toner adhesion roll 52 that is rotatably supported at a position facing the photosensitive drum 12, and a position separated from the photosensitive drum 12 (the toner adhesion roll 52 of the toner adhesion roll 52. A toner peeling roll 54 rotatably supported on the side opposite to the photosensitive drum 12, and an endless belt-like brush member 56 suspended from the toner adhesion roll 52 and the toner peeling roll 54. . As shown in FIG. 3, the brush member 56 is obtained by implanting a large number of medium resistance brush fibers 60 on the surface of a base 58 formed of an endless belt of medium resistance.

  As shown in FIG. 2, a motor 80 is connected to the support shaft of the toner adhesion roll 52, and the toner adhesion roll 52 rotates in the direction of arrow B in FIG. The rotation of the toner adhering roll 52 causes the brush member 56 to rotate in the direction of arrow C in FIG. 2, and the toner peeling roll 54 rotates accordingly. The brush member 56 moves in a direction opposite to the rotation direction of the photosensitive drum 12 at a position where it is in contact with the photosensitive drum 12.

  A plate-like fixed electrode 62 that contacts the back surface of the base 58 of the brush member 56 is provided between the toner adhesion roll 52 and the toner peeling roll 54 in the moving direction of the brush member 56.

  The toner adhesion roll 52 is made of a conductive member, and a voltage (for example, +300 V) having a polarity opposite to that of the toner T (for example, a negative polarity) is applied from a power source 64. As a result, a potential difference is generated between the photosensitive drum 12 and the brush member 56 on the toner adhesion roll 52 so that the toner T on the photosensitive drum 12 is attracted to the brush member 56.

  The toner peeling roll 54 is made of a conductive member, and a voltage (for example, −300 V) having the same polarity as that of the toner T (for example, negative polarity) is applied from the power source 66. As a result, a repulsive force acts between the toner T and the brush member 56 on the toner peeling roll 54 so that the toner T on the surface of the brush member 56 is removed. The fixed electrode 62 is disposed immediately before the toner peeling roll 54 in the moving direction of the brush member 56, and a voltage (for example, −300 V) having the same polarity as the toner T (for example, negative polarity) is supplied from the power source 66. Applied.

  A flicker member 68 is disposed on the surface side of the brush member 56 at the position where the toner peeling roll 54 is provided so as to be in contact with the brush fibers 60. The flicker member 68 has a plate shape and is disposed in a direction orthogonal to the moving direction of the brush member 56. Further, the flicker member 68 is provided over substantially the entire length of the brush member 56 in the longitudinal direction.

  A collection tray 70 for collecting the peeled toner is disposed below the surface of the brush member 56 provided with the toner peeling roll 54. Inside the collection tray 70, an auger 72 that conveys toner in a certain direction is provided. A toner recovery box (not shown) is disposed at the end of the auger 72 in the conveyance direction.

  Further, the diameter (φ) of the toner adhesion roll 52 and the toner peeling roll 54 is about 12 mm, and each is formed of SUS. The rotation speed of the toner adhesion roll 52 is 75 mm / s.

The brush member 56 is made of polyimide as the material of the base body 58, and the volume resistance is set to 5 × 10 ¹⁰ Ωcm. Further, nylon is used as the material of the brush fiber 60, the fiber diameter is about 2.0d (denier), and the fiber length is about 5.0mm. The moving speed of the brush member 56 is 75 mm / s. The fixed electrode 62 is made of SUS, and the contact width with the brush member 56 is 15 mm. The charge amount of the toner is −30 μC / g.

  Next, the operation of this embodiment will be described.

  After the toner image is transferred to the intermediate transfer belt 30, the transfer residual toner or the like is attached to the photosensitive drum 12. As shown in FIG. Pass through the contact area. A toner adhering roll 52 is disposed inside the brush member 56 facing the photosensitive drum 12, and a voltage (for example, +300 V) having a polarity opposite to that of the toner is applied from the power source 64 to the toner adhering roll 52. Yes. As a result, the toner T remaining on the photosensitive drum 12 is electrostatically attracted to the brush member 56, and the toner T is collected on the surface of the brush fiber 60.

  The toner T adhering to the brush fiber 60 is transported to the position where the toner peeling roll 54 is disposed as the brush member 56 moves in the direction of arrow C. A voltage (for example, −300 V) having the same polarity as the toner is applied to the toner peeling roll 54 from a power source 66. As a result, a repulsive force acts between the toner T and the brush member 56, so that the toner attached to the brush fiber 60 is removed. Further, at the position where the brush member 56 is suspended from the toner peeling roll 54, the flicker member 158 is in contact with the brush fiber 60, and the toner T adhering to the brush fiber 60 is removed. The peeled toner T falls to the collection tray 70, is conveyed in a fixed direction by the auger 72, and is collected in a toner collection box (not shown).

  Further, immediately before the brush member 56 reaches the toner peeling roll 54, a voltage (for example, −300 V) having the same polarity as the toner T is applied to the fixed electrode 62 from the power source 66. Although the brush fiber 60 is made of a medium-resistance resin, applying a voltage having the same polarity as that of the toner T immediately before reaching the toner peeling roll 54 allows the potential fluctuation of the brush fiber 60 to be delayed. At the position of the toner peeling roll 54, the tip of the brush fiber 60 has an optimum potential. For this reason, the toner T adhering to the brush member 56 is stably removed. Accordingly, even when the image forming apparatus 100 outputs at high speed, it is possible to prevent the occurrence of defective cleaning.

  In such an image forming apparatus 100, the removal of the toner T adhering to the brush fiber 60 uses an electrostatic force, so that it is possible to prevent the toner from being stressed by a mechanical force. Therefore, even when a low-melting toner is used, filming does not occur in the brush member 56, and the detoning ability is not lowered due to this filming.

  Further, the recovery of the toner T from the photosensitive drum 12 and the removal of the toner T from the brush fiber 60 are performed by applying a bias to the toner adhesion roll 52, the toner peeling roll 54, and the fixed electrode 62. Therefore, it is not necessary to provide a complicated function such as switching, and a nip electric field necessary for toner movement can be stably formed. For this reason, it is possible to stably suppress the occurrence of defective cleaning over a long period of time.

  Further, by arranging the fixed electrode 62 immediately before the peeling position where the toner peeling roll 54 is arranged and applying a voltage having the same polarity as that of the toner T, the potential fluctuation delay of the brush fiber 60 is suppressed. The toner can be reliably removed from the brush fiber 60. For this reason, it is possible to suppress the occurrence of cleaning failure even in the image forming apparatus 100 that outputs at high speed.

  Next, a cleaning device according to a second embodiment of the present invention will be described.

  In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 4, in this cleaning device 150, a small-diameter toner peeling roll is provided at a position spaced apart from the photosensitive drum 12 inside the brush member 56 (on the side opposite to the photosensitive drum 12 of the toner adhesion roll 52). 152 and a small-diameter support roll 154 are disposed on the downstream side of the toner peeling roll 152. The brush member 56 is suspended by a toner adhering roll 52, a toner peeling roll 152, and a support roll 154, and the brush member 56 moves around in the direction of arrow C in FIG. The brush member 56 is wound around the toner peeling roll 152 with a small diameter so as to be substantially perpendicular, and the brush member 56 is moved from below to above at the position of the toner peeling roll 152.

  In addition, a flicker member 158 is disposed in contact with the brush fiber 60 at a position where the brush member 56 is wound around the toner peeling roll 152. The flicker member 158 has a plate shape and is arranged in a direction perpendicular to the surface of the base body 58. Further, the flicker member 158 is provided over substantially the entire length of the brush member 56 in the longitudinal direction.

  Further, on the upstream side of the toner peeling roll 152, a plate-like fixed electrode 156 that contacts the back surface of the base body 58 of the brush member 56 is disposed. The toner peeling roll 152 and the fixed electrode 156 are made of a conductive member, and a voltage (for example, −300 V) having the same polarity as the toner T (for example, negative polarity) is applied from the power source 66. Further, the diameter (φ) of the toner peeling roll 152 is set to about 7.0 mm, and the diameter (φ) of the support roll 154 is set to about 7.0 mm.

  In such a cleaning device 150, a voltage having the same polarity as that of the toner T is applied to the fixed electrode 156 before the brush member 56 reaches the toner peeling roll 152. The tip of the brush fiber 60 has an optimum potential. For this reason, the toner T of the brush fiber 60 can be stably removed, and the occurrence of defective cleaning can be prevented even when output at a high speed.

  Further, the brush member 56 is wound around a small-diameter toner peeling roll 152 at a substantially right angle, and a flicker member 158 is disposed at a portion where the curvature is large and the density of the brush fiber 60 is coarsened by the toner peeling roll 152. ing. By this flicker member 158, the toner T can be removed from the brush fiber 60, and the toner T can be removed stably.

  Next, a test for examining the toner removal effect by the cleaning device 50 of the first embodiment (see FIG. 2) will be described.

  Here, specifications of main members and main electric specifications are described.

Brush member 56: Base body 58: Polyimide
Volume resistance: 5 × 10 ¹⁰ Ωcm
Brush fiber 60: Nylon
Fiber diameter: 2.0d (denier)
Fiber length: 5.0mm
Rotation speed: 75mm / s
Diameter φ of toner adhesion roll 52: 12 mm
Material: SUS
Rotation speed: 75mm / s
Diameter φ of toner peeling roll 54: 12 mm
Material: SUS
Rotation speed: 75mm / s
Contact width of the fixed electrode 62: 15 mm
Material: SUS
Charge amount of toner T: −30 μC / g
The evaluation was performed by printing 100,000 sheets of A3 size recording paper continuously.

  Table 1 shows the case where the voltage applied to the release portion (toner peeling roll 54 and fixed electrode 62) is changed and the fixed electrode 62 for release is arranged (first embodiment) and the case where it is not arranged (comparative example). The result of having evaluated the generation | occurrence | production condition of the cleaning defect in each of these is shown. In this test, evaluation was performed by changing the process speed in two stages of 220 mm / s and 400 mm / s. The voltage applied to the toner adhesion roll 52 is fixed at + 300V.

  The toner removal effect was visually observed. In the evaluation of Table 2, “◯” indicates that almost no cleaning failure occurs, “Δ” indicates that the cleaning failure occurs, but “×” indicates that the cleaning level is acceptable, and “x” indicates that many cleaning failures occur.

表１から以下のことが言える。

From Table 1, the following can be said.

  (1) A cleaning failure occurs when the voltage applied to the release portion is low. This is considered to be because the detoning effect of the brush member 56 is not sufficiently obtained, and the toner is saturated on the brush member 56, so that the cleaning performance is deteriorated.

  (2) When the voltage applied to the release portion is high, a cleaning failure occurs. This phenomenon affects the cleaning section where the voltage applied to the release section comes into contact with the photosensitive drum 12 via the brush member 56, so that a sufficient bias cannot be obtained at the cleaning section, and the cleaning performance deteriorates. It is thought that

  (3) By disposing the fixed electrode 62, the cleaning property is improved. This effect is particularly remarkable when the output is high speed (when the process speed is 400 mm / s), and before reaching the release position (toner peeling position) where the toner peeling roll 54 is disposed, the fixed electrode 62. This is considered to be because the optimum potential at the tip of the brush fiber 60 can be obtained at the release position even when there is a delay in the potential fluctuation of the brush fiber 60 by starting to apply a bias to the brush fiber 60.

  In the image forming apparatus 100, the transfer residual toner attached to the photosensitive drum 12 is removed by the cleaning device 50. However, the present invention is not limited to this configuration. For example, the cleaning device of the present invention can also be applied when removing the transfer residual toner attached to the intermediate transfer belt 30.

1 is a schematic configuration diagram illustrating an image forming apparatus including a cleaning device according to a first embodiment of the present invention. It is a block diagram which shows the cleaning apparatus used with the image forming apparatus shown in FIG. It is the elements on larger scale which show the brush member of the cleaning apparatus shown in FIG. It is a block diagram which shows the cleaning apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

10Y, 10M, 10C, 10K Image forming unit 12 Photosensitive drum 50 Cleaning device 52 Toner adhesion roll 54 Toner peeling roll 56 Brush member 58 Base 60 Brush fiber 62 Fixed electrode 64 Power supply 66 Power supply 68 Flicker member 100 Image forming apparatus 150 Cleaning device 152 Toner peeling roll 154 Support roll 156 Fixed electrode 158 Flicker member

Claims (4)

A cleaning device arranged to contact an image carrier on which a toner image is carried, and for cleaning toner from the image carrier,
A roller for toner adhesion, which is rotatably supported facing the image carrier, and has a polarity opposite to that of the toner;
A toner peeling roll that is rotatably supported at a position spaced from the image carrier and has the same polarity as the toner;
A belt-like brush member suspended on the toner adhering roll and the toner peeling roll and moving around in contact with the image carrier;
A cleaning device comprising:   The cleaning device according to claim 1, further comprising a fixed electrode having the same polarity as the toner that contacts the back surface of the brush member immediately before the position where the toner is peeled from the brush member.   The cleaning apparatus according to claim 1, wherein a flicker member that contacts brush fibers of the brush member is provided at a position where toner is peeled from the brush member.   An image forming apparatus comprising the cleaning device according to claim 1.

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