JP3888675B2 - Cleaning device and image forming apparatus having the cleaning device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning device that removes toner adhering to the surface of an object to be cleaned and cleans the surface, and an image forming apparatus having the cleaning device.
[0002]
[Prior art]
The above-described type of cleaning device that cleans the object to be cleaned has been widely used in image forming apparatuses configured as copying machines, printers, facsimiles, or the like. Such a cleaning device is configured, for example, as a cleaning device that cleans the peripheral surface of the charging roller that charges the image carrier, or a cleaning device that cleans the surface of the transfer belt.
[0003]
As such a cleaning device, a cleaning device including a cleaning brush that comes into contact with the surface of an object to be cleaned is widely used. This type of cleaning device can effectively remove the toner adhering to the surface of the cleaning brush while the cleaning brush contacts the surface of the object to be cleaned.
[0004]
However, when a large amount of toner adheres to the object to be cleaned, the toner cannot be removed all at once by the cleaning brush, and a lot of toner remains on the object to be cleaned that has passed through the cleaning brush. Causes various problems. For example, when the object to be cleaned is composed of a charging roller of the image forming apparatus and a cleaning roller is rotated, the following problem occurs.
[0005]
The image carrier is charged by a charging roller, and the charged image carrier is exposed to form an electrostatic latent image. The electrostatic latent image is visualized as a toner image, and the toner image is used as a transfer material. In an image forming apparatus in which the surface of the image carrier after the transfer is cleaned by a cleaner, the image carrier after passing the cleaner is charged by a charging roller, so that the toner image can be prevented from being soiled. it can. When the toner on the image carrier that cannot be completely removed by the cleaner adheres to the surface of the charging roller, the toner attached to the surface of the charging roller is removed by a cleaning brush comprising a brush roller in contact with the surface.
[0006]
However, if the cleaner's ability to remove toner decreases due to environmental changes, deterioration of the cleaning member in the cleaner, and the like, a relatively large amount of toner passes through the cleaner, and the toner adheres to the surface of the charging roller. May adhere. In this case, the toner attached to the surface of the charging roller by the brush roller cannot be removed at once, and the toner on the surface of the charging roller is gradually removed while the brush roller rotates several times. become. For this reason, toner that could not be completely removed by the brush roller remains on the charging roller. However, if the image forming operation is performed while the image bearing member is charged by the charging roller, charging unevenness or charging of the image bearing member is performed. Defects may occur, which may cause abnormal images.
[0007]
[Problems to be solved by the invention]
The first object of the present invention is to provide a cleaning device capable of efficiently removing toner even when a large amount of toner adheres to the surface of the charging roller. An image forming apparatus having such a cleaning device is provided. The second purpose is to provide it.
[0008]
[Means for Solving the Problems]
The present invention, in order to achieve the first object, in a cleaning device having a cleaning brush for removing toner adhered to the contact with the surface on the surface of the charging roller, the fibers of the brush of the cleaning brush, charging by contact with the surface of the roller is formed of a material which frictionally charged to the charging polarity opposite to the toner deposited on the surface of the charging roller, the cleaning brush, as a brush roller having a contact with the brush to the surface of the charging roller The brush roller is arranged such that the brush abuts on the surface of the charging roller by its own weight and rotates following the movement of the surface of the charging roller, and the weight of the brush roller There is proposed a cleaning apparatus characterized in that it is set below 200g at least 50 g (according 1).
[0009]
In that case, it is advantageous that the length of the fibers of the brush is set to 2 mm or less .
[0010]
In the cleaning device according to claim 1 or 2, it is advantageous that the thickness of the brush fiber is 2 denier or less and the density of the fiber is set to 20000 / cm ² or more (claim). 3).
[0011]
In order to achieve the second object , the present invention proposes an image forming apparatus comprising the cleaning device according to claim 1, 2 or 3 and a charging roller. ).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an exemplary embodiment in which the member to be cleaned is composed of a charging roller of an image forming apparatus will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a cross-sectional view showing an example of an image forming apparatus. The image forming apparatus shown here is configured as an electronic copying machine, a printer, a facsimile, or a multifunction machine having at least two of these functions. is there.
[0016]
The image forming apparatus shown in FIG. 1 has an image carrier 1 configured as a drum-shaped photoreceptor, and the image carrier 1 is rotationally driven in the direction of arrow A as the image forming operation starts. At this time, the charging roller 2 disposed opposite to the surface of the image carrier rotates in the direction of arrow B by a driving device (not shown) or following the movement of the surface of the image carrier 1. The charging roller 2 includes a cored bar 3 and a resistance layer 4 fixed around the cored bar 3. When the charging roller 2 rotates as described above, a charging voltage having a predetermined polarity is applied to the cored bar 3. The surface of the image carrier 1 is charged with a predetermined polarity. Here, it is assumed that the image carrier is charged with a negative polarity. It is also possible to use an image carrier comprising an endless belt that is wound around a plurality of rollers and driven to rotate.
[0017]
The surface of the charged image carrier 1 is irradiated with a light-modulated laser beam LB emitted from a laser writing unit (not shown) which is an example of an exposure apparatus, and thereby the electrostatic latent image is applied to the image carrier. Is formed. This electrostatic latent image is visualized as a toner image by the developing device 5. The developing device 5 shown here has a developing case 6 containing a dry developer D, and a developing roller 7 that carries and transports the developer D, and the developing roller 7 that is rotationally driven in the direction of arrow C is shown in FIG. The developer toner carried on the peripheral surface is electrostatically transferred to an electrostatic latent image formed on the image carrier, and the latent image is visualized as a toner image. As the developer D, a two-component developer having a toner and a carrier or a one-component developer having no carrier can be used. Here, a two-component developer is used, and the toner is It is assumed that it is charged to a predetermined polarity by the friction with the carrier, in the example shown in the figure, to a negative polarity.
[0018]
A transfer belt 8 driven in the direction of arrow E is disposed opposite to the image carrier 1, and transfer paper P, which is an example of a transfer material fed from a paper supply unit (not shown), is placed on the transfer belt 8. It is carried and carried. When the transfer paper P passes through the transfer region between the image carrier 1 and the transfer belt 8, a transfer voltage is applied to the transfer device 9 disposed opposite to the image carrier 1 with the transfer belt 8 interposed therebetween, whereby the image carrier The toner image formed on the body surface is electrostatically transferred onto the transfer paper P. It is also possible to transfer the toner image formed on the image carrier onto a transfer material made of an intermediate transfer member, and transfer the transferred toner image onto a transfer paper as the final transfer material.
[0019]
The transfer residual toner adhering to the surface of the image carrier after the toner image is transferred is scraped and removed by the two cleaning members of the cleaner brush 10 and the cleaner blade 11 that are in pressure contact with the surface of the image carrier. On the other hand, the transfer paper P to which the toner image has been transferred passes through a fixing device (not shown), and at this time, the toner image is fixed on the transfer paper by the action of heat and pressure.
[0020]
In the image forming apparatus shown in FIG. 1, the image carrier 1, the charging roller 2, the cleaner brush 10, and a cleaning brush 12 to be described later are rotatably assembled to the unit case 13, and the base end portion of the cleaner blade 11 is The unit process 13 is fixed to the unit case 13, and an integrated process cartridge 14 is constituted by these elements. The process cartridge 14 can be pulled out along the guide rail 15 fixed to the main body of the image forming apparatus or pushed into the back side to load the process cartridge 14 at a predetermined position. The cleaner 17 for the image carrier that cleans the surface of the image carrier is constituted by the cleaner brush 16, the cleaner blade 11, and the cleaner case 16 constituted by a part of the unit case 13.
[0021]
As described above, the charging roller 2 is used to charge the image carrier 1 while facing the image carrier. As shown in FIG. 1, the roller 2 may be in pressure contact with the surface of the image carrier 1, but a minute gap is formed from the surface of the image carrier 1, and the roller 2 is positioned in a non-contact state with respect to the image carrier. You may do it.
[0022]
When the image forming operation as described above is performed, the cleaner 17 removes the transfer residual toner on the image carrier, but it is difficult to remove all the toner, and a small amount of toner passes through the cleaner blade 11. The foreign matter such as the toner slipped through in this way and the toner floating in the image forming apparatus main body adheres to the peripheral surface of the charging roller 2. If this is left unattended, uneven charging or poor charging of the image carrier occurs, and the image quality of the toner image formed on the image carrier deteriorates.
[0023]
Therefore, the image forming apparatus of this example is provided with a charging roller cleaning device 18 provided with the cleaning brush 12 described above. The brush of the cleaning brush 12 comes into contact with the surface of the object to be cleaned (charging roller 2 in this example) and removes the toner adhering to the surface.
[0024]
In the illustrated example, the cleaning brush 12 is configured as a rotating brush roller 12A. The brush roller 12A extends parallel to the charging roller 2, and as shown in FIGS. 2 and 3, a metal or hard resin is used. And a brush 20 made of a large number of fibers having a base end fixed to the peripheral surface of the core shaft 19. The brush 20 is provided over the entire circumference of the core shaft 19 in the range indicated by the symbol W in FIG. As shown in FIGS. 1 and 2, the brush 20 abuts on the surface of the object to be cleaned, that is, the surface of the charging roller 2, and the toner attached to the charging roller 2 can be efficiently removed. Thus, the brush roller has a brush that comes into contact with the surface of the object to be cleaned.
[0025]
The brush roller 12A may be rotationally driven by a driving device (not shown). However, the brush roller 12A shown here has a brush 20 that is to be cleaned by the weight of the brush roller 12A, that is, the surface of the charging roller 2. Is arranged so as to rotate in the direction of arrow G following the movement of the surface of the object to be cleaned.
[0026]
Specifically, as shown in FIG. 1 and FIG. 2, bearing members 21 are respectively provided on the side plate 13A on the back side of the unit case 13 and the side plate (not shown) on the near side as shown by the chain line in FIG. Each of the bearing members 21 is fixed, and a guide slot 22 having an open lower portion is formed in each of the bearing members 21, and each longitudinal end portion of the core shaft 19 of the brush roller 12 </ b> A is rotatable in the guide slot 22. It fits along the slot 22 so as to be slidable in the direction of arrow F (direction approaching or separating from the surface of the object to be cleaned). The width of each guide slot 22 is set to be slightly larger than the diameter of each end portion of the core shaft 19, so that each end portion of the core shaft 19 can be fitted into each guide slot 22 without rattling.
[0027]
Since the brush roller 12A is located in the upper region of the charging roller 2 and each end of the core shaft 19 is slidably fitted in the guide slot 22, the brush roller 12A has the brush 20 The roller 12A comes into contact with the surface of the charging roller 2 due to its own weight. In addition, since each end of the core shaft 19 is rotatably fitted in the guide slot 22, the brush roller 12 </ b> A is driven by the movement of the surface of the charging roller 2 when the charging roller 2 rotates in the arrow B direction. And can be rotated in the direction of arrow G. The brush roller 12A rotates with the rotation of the charging roller 2. At this time, the brush 20 in contact with the surface of the charging roller 2 removes the toner adhering to the surface of the charging roller 2 and cleans the surface. is there.
[0028]
Here, as described above, the amount of residual toner that passes through the cleaner 17 when a large environmental change and the deterioration of the cleaner brush 10 and the cleaner blade 11 of the cleaner 17 overlap. And the toner may adhere to the surface of the charging roller 2. In such a case, in the conventional cleaning device, a large amount of toner on the charging roller cannot be removed at once by the cleaning brush, and thus there is a risk that an abnormal image may be generated.
[0029]
Therefore, in the cleaning device 18 of the present example, the fibers of the brush 20 of the cleaning brush 12 come into contact with the surface of the object to be cleaned (charging roller 2 in this example), and the toner adhering to the surface of the object to be cleaned is removed. It is made of a material that is triboelectrically charged to a polarity opposite to the charging polarity. In the image forming apparatus shown in FIG. 1, since the charging roller 2 is configured to negatively charge the image carrier, the toner attached to the surface of the charging roller 2 is also negatively charged. Therefore, the brush 20 of the brush roller 12 </ b> A is made of a material that is positively charged when the brush 20 comes into contact with the surface of the charging roller 2, such as a silicone resin or nylon 66.
[0030]
According to the above-described configuration, even when a large amount of toner adheres to the peripheral surface of the charging roller 2, the toner can be electrostatically attracted to the brush 20 side. The toner can be adsorbed to 12A and the removal efficiency of the toner adhering to the charging roller 2 can be increased. As a result, the image bearing member 1 is not charged by the charging roller 2 while a large amount of toner is attached to the peripheral surface of the charging roller 2, or the toner is hardly attached, or the toner is attached. The image carrier 1 can be charged by the charging roller 2 having a very small amount. Therefore, it is possible to effectively suppress the occurrence of uneven charging and poor charging of the image carrier 1, and to expose and develop the image carrier 1 to form a high quality image.
[0031]
Even when a cleaning brush having a configuration other than the brush roller is used, the above-described effects can be similarly obtained.
[0032]
By the way, in the conventional cleaning device, the brush roller is rotationally driven by a driving device, and a difference is made between the linear velocity of the brush contacting the surface of the object to be cleaned and the linear velocity of the surface of the object to be cleaned. The surface of the cleaning body is cleaned by scraping off the toner adhering to the surface of the cleaning body. However, according to this configuration, not only a driving device for driving the brush roller is required, but also means for restricting the amount of biting of the brush is provided in order to suppress permanent deformation of the brush fiber, which is generally referred to as the falling of the brush. There is a need. For this reason, the cost of a cleaning device rises and the fault that the structure becomes complicated is inevitable. The amount of biting of the brush is the maximum amount of deformation of the brush in the radial direction of the brush roller when the brush roller is pressed against the surface of the object to be cleaned. In the case of a conventional brush roller, this amount of biting By controlling so that the value falls within the appropriate range, the fall of the brush was suppressed.
[0033]
On the other hand, in the cleaning device 18 of this example, the brush roller 12A is not driven to rotate by the driving device, but is rotated by the rotation of the charging roller 2, so that the brush roller 12A is driven to rotate. This eliminates the need for a device, thereby simplifying the configuration of the cleaning device 18 and reducing its cost. In addition, since the brush 20 does not hit the surface of the charging roller 2 excessively, wear on the surface of the charging roller 2 can be suppressed.
[0034]
Further, the brush roller in a state where the brush roller 12A is in contact with the charging roller 2 from the sum of the radius of the brush roller 12A and the radius of the charging roller 2 when the brush roller 12A is not in contact with the charging roller 2 The value obtained by subtracting the distance between the center of 12A and the center of the charging roller 2 is the amount of biting of the brush 20, but if the amount of biting becomes too large, the fibers of the brush 20 deteriorate early and this is permanent. If the deformation occurs, the brush falls, and the brush bite amount is too small, the cleaning efficiency of the surface of the charging roller 2 is lowered. Therefore, conventionally, as described above, the amount of biting of the brush is regulated by adjusting the relative position of the both so that the distance between the center of the brush roller and the center of the charging roller is constant. In the cleaning device 18 of the example, the brush roller 12A is configured to come into contact with the surface of the charging roller 2 by its own weight, so that a desired amount of biting of the brush can be obtained only by adjusting the weight of the brush roller 12A. Therefore, it is possible to omit the regulation means provided in the past. Thereby, simplification of the structure of the cleaning device 18 and cost reduction can be achieved.
[0035]
The length of the fibers of the brush 20 can be set as appropriate, but it is desirable to set the length to 2 mm or less, particularly 0.4 to 0.6 mm. The length of this fiber is the length of the free fiber portion excluding the fiber portion fixed to the core shaft 19. If the length of the fiber is shortened in this way, the bending moment acting on the base end portion of the fiber that is elastically bent and deformed by being pressed against the surface of the charging roller 2 can be reduced. Thereby, it is possible to more effectively suppress the occurrence of brush collapse (permanent deformation) over a long period of time, thereby extending the life of the brush roller 12A. When the fiber length of the brush 20 is longer than 2 mm, the distance between the fibers at the tip end of the fiber increases, so that the load applied to each fiber in contact with the surface of the charging roller 2 increases, thereby increasing the brush. However, such a problem can be avoided by setting the fiber length to 2 mm or less.
[0036]
Generally, in order to remove the toner adhering to the tip of the brush of the brush roller, it is normal to hit the brush against the flicker. However, if the fiber length of the brush 20 is shortened as described above, As shown in FIG. 1, the toner attached to the tip of the brush can be removed without hitting the brush 20 against the flicker. The reason for this is not necessarily clear, but if the fibers are as short as 2 mm or less, the fibers that are elastically deformed by being pressed against the surface of the charging roller 2 will be removed from the charging roller 2 as the brush roller 12A rotates. When it leaves, it is elastically restored to its original form instantly, and this is considered to be because the toner adhering to the tip of the fiber jumps out of the fiber due to the impact at this time.
[0037]
The thickness and density of the fibers of the brush 20 can be set as appropriate. When the thickness is set to 2 denier or less and the density of the fibers is set to 20000 / cm ² or more, particularly 30000 / cm ² , the charging roller A large number of fibers come into contact with the surface of 2, whereby the load applied to each fiber can be reduced. This also can prevent the brush from falling over a long period of time. Further, when the density of the fibers is increased in this way, the number of fibers contacting the surface of the charging roller increases, so that the surface of the charging roller 2 can be efficiently cleaned and the unevenness of the stain can be eliminated. It is possible to always form a high-quality image on the top.
[0038]
Further, the weight of the brush roller 12A can be set as appropriate. In particular, when the weight is set to 50 g or more and 200 g or less, an appropriate biting amount of the brush 20 can be guaranteed and the brush roller 12A can be smoothly rotated. It becomes possible. If the weight of the brush roller 12A is smaller than 50 g, the amount of biting of the brush is too small, and the cleaning efficiency of the surface of the charging roller 2 is reduced. If the weight is larger than 200 g, the amount of biting of the brush is excessively large. It becomes easy to promote the fall of the brush.
[0039]
The brush 20 can be fixed to the core shaft 19 by an appropriate method. In particular, when the fiber base end portion of the brush 20 is fixed to the peripheral surface of the core shaft 19 of the brush roller by the electrostatic flocking method, the core shaft 19, short fibers can be planted with high density. Thereby, it is possible to prevent the brush from falling over a long period of time and to extend the life of the brush roller 12A.
[0040]
For example, an adhesive is applied to the range W of the core shaft 19, the base end portions of a large number of fibers are electrostatically attached to the adhesive, and the base end portions of the fibers are connected to the core shaft 19 via the adhesive. Can be fixed to.
[0041]
When the object to be cleaned is a rotating body formed in a columnar shape like the charging roller 2 shown in FIG. 1, as shown in FIG. 4, a horizontal line H passing through the rotation center O of the rotating body 2A. If the brush roller 12A is brought into contact with the range S of the rotating body circumferential surface above the brush 20, the brush 20 can be brought into contact with the rotating body without any trouble by the weight of the brush roller 12A.
[0042]
The example of the cleaning device in the case where the member to be cleaned is the charging roller 2 that faces the image carrier 1 and charges the image carrier 1 has been described above, but various members to be cleaned other than the charging roller 2 are cleaned. Therefore, the cleaning device having each configuration described above can be used. For example, the above-described configurations can also be employed in a cleaning device that removes toner adhering to the transfer belt 8 shown in FIG.
[0043]
As in the example shown in FIG. 1, at least the cleaning device 18 and the object to be cleaned such as the charging roller 2 can be assembled together to form the process cartridge 14. However, the brush roller 12 A of the cleaning device 18 can be configured. If the length of the brush fiber is set to 2 mm or less as described above, the diameter of the brush roller 12A can be made extremely small, so that an advantage that the process cartridge 14 can be reduced in size can be obtained. The same applies to an image forming apparatus including a cleaning device and an object to be cleaned, and the image forming apparatus can be downsized.
[0044]
【The invention's effect】
According to the invention according to claims 1 to 3, it is possible to increase the removal efficiency of the toner by the cleaning brush, a large amount of toner is also a long time, the charging roller on when a large amount of toner adheres to the charging roller on the It is possible to prevent problems that remain.
[0045]
According to the invention concerning Claim 4 , the image forming apparatus provided with the cleaning apparatus which has the effect mentioned above can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus.
FIG. 2 is an enlarged view of a brush roller.
FIG. 3 is a front view of a brush roller.
FIG. 4 is a diagram for explaining a position where a brush roller is disposed with respect to an object to be cleaned.
[Explanation of symbols]
12 Cleaning brush 12A Brush roller 18 Cleaning device 20 Brush

Claims (4)

In the cleaning apparatus having a cleaning brush for removing contact with the surface of the charging roller toner attached to the surface, the fibers of the brush of the cleaning brush, the contact with the surface of the charging roller, the surface of the charging roller The cleaning brush is configured as a brush roller having a brush that comes into contact with the surface of the charging roller, and the brush is composed of the brush. The brush roller is arranged so as to abut on the surface of the charging roller by its own weight and rotate following the movement of the surface of the charging roller, and the weight of the brush roller is set to 50 g or more and 200 g or less. And a cleaning device. The cleaning device according to claim 1, wherein the length of the fibers of the brush is set to 2 mm or less . The cleaning device according to claim 1 or 2, wherein the thickness of the brush fibers is 2 denier or less and the density of the fibers is set to 20000 / cm ² or more . An image forming apparatus comprising the cleaning device according to claim 1, 2 or 3 and a charging roller .

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