JP2018054770A - Image forming apparatus, developing device, and bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can reduce a variation in distance between an image holding body and a developing roll compared with a technology not having regulation means that regulates at least one of the maximum value of the distance between the image holding body and developing roll and the minimum value of the distance between the image holding body and developing roll, a developing device, and a bearing.SOLUTION: An image forming apparatus 10 comprises: coil springs 94 that each urge a developing roll 220 to be brought closer to a photoreceptor drum 34; and distance regulation mechanisms 800 that each include a viscoelastic body 320, and regulate at least one of the maximum value of the distance between the photoreceptor drum 34 and developing roll 220 and the minimum value of the distance between the photoreceptor drum 34 and developing roll 220 so that the distance between the photoreceptor drum 34 and developing roll 220 falls within a predetermined range. The distance regulation mechanism 800 includes a bearing 300 that supports the developing roll 220, and the viscoelastic body 320 is provided in the bearing 300.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus, a developing device, and a bearing.

  In Patent Document 1, a gap between the photosensitive drum (image holding member) and the developing roller is regulated by a gap regulating roller (tracking roll) that is provided coaxially with the developing roller and contacts the surface of the photosensitive drum. In addition, in the developing device in which at least the flange member is press-fitted on the inner surface of both ends of the photosensitive drum, the gap regulating roller is inlaid on the inner surface of the photosensitive drum surface. A developing device is disclosed that is provided so as to be in contact with a portion other than the portion that is provided.

JP 2006-330676 A

  In the developing device as described above, since the diameter of the developing roll is not constant and has a runout, the runout of the developing roll causes a variation in the distance between the image holding member and the developing roll, and the distance of this distance There is a risk that unevenness of image density may occur due to the fluctuation. It is conceivable to use a viscoelastic body in order to reduce the above-described variation in distance. However, when viscoelasticity is used, the distance between the image carrier and the developing roll may not be within a desired range due to deterioration of viscoelasticity or excessive deformation of the viscoelastic body.

  The present invention relates to an image carrier, compared to a technique that does not have a restriction means for regulating at least one of the maximum value of the distance between the image carrier and the developing roll and the minimum value of the distance between the image carrier and the developing roll. It is an object of the present invention to provide an image forming apparatus, a developing apparatus, and a bearing that can suppress fluctuations in the distance to the developing roll.

  According to a first aspect of the present invention, there is provided an image carrier that develops a latent image, a developing roll that is provided opposite to the image carrier and that develops the latent image of the image carrier, and the image carrier. And an urging means for urging the developer roll so as to approach each other, a viscoelastic body that deforms according to a change in distance between the image carrier and the developer roll, and the image carrier and the developer roll. At least one of the maximum value of the distance between the image carrier and the developing roller and the minimum value of the distance between the image carrier and the developing roller so that the distance between the image carrier and the developing roller is within a predetermined range. An image forming apparatus provided with a bearing for supporting the developing roll so that the developing roll can be rotated, and the viscoelastic body is provided on the bearing. It is.

  According to a second aspect of the present invention, the bearing includes an outer ring member, an inner ring member that supports the developing roll and is disposed inside the outer ring portion, and the viscoelastic body. The image forming apparatus according to claim 1, wherein the elastic body is mounted so as to be sandwiched between the outer ring member and the inner ring member.

  According to a third aspect of the present invention, the developing roll includes a developer holding portion that holds a developer, and a large-diameter portion that has a larger diameter than the developer holding portion. 3. The image forming apparatus according to claim 1, wherein a minimum value of a distance between the image carrier and the developing roll is regulated by bringing a large diameter portion into contact with the image carrier.

  According to a fourth aspect of the present invention, the distance regulating means regulates the maximum value of the distance between the image holding member and the developing roll by bringing a part of the developing roll into contact with the outer ring member. The image forming apparatus according to claim 1.

  The present invention according to claim 5 is characterized in that the viscoelastic body is made of a material containing any one of polyimide, polyethylene terephthalate, polyoxymethylene resin, or polyacetal resin. This is an image forming apparatus.

  According to a sixth aspect of the present invention, there is provided a developing roll that is provided opposite to an image holding body on which a latent image is developed, and that develops the latent image of the image holding body, and the image holding body and the developing roll. An urging unit that urges the image holder and the developing roll to move closer to each other; a viscoelastic body that deforms according to a change in the distance between the image holding body and the developing roll; and a distance between the image holding body and the developing roll is predetermined. A distance regulating means for regulating at least one of a maximum value of a distance between the image carrier and the developing roll and a minimum value of a distance between the image carrier and the developing roll so as to be within a predetermined range; The distance regulating means has a bearing that supports the developing roll so as to rotate, and the viscoelastic body is a developing device provided in the bearing.

  The present invention according to claim 7 is used for the developing roll, and the developing roll and the image holding body are arranged so that the distance from the image holding body facing the developing roll is within a predetermined range. A bearing used to regulate at least one of the maximum value of the distance and the minimum value of the distance between the developing roll and the image carrier, the bearing supporting the outer ring member and the rotating body, An inner ring member disposed on the inner side of the outer ring member, and a viscoelastic body that is mounted between the outer ring member and the inner ring member and deforms in accordance with a change in positional relationship between the outer ring member and the inner ring member. And a bearing.

  According to the first aspect of the present invention, compared with a technique that does not have a restricting means for restricting at least one of the maximum distance between the image carrier and the developing roll and the minimum distance between the image carrier and the developing roll. In addition, it is possible to suppress fluctuations in the distance between the image carrier and the developing roll, and furthermore, an image forming apparatus having a simple structure as compared with the technique in which the viscoelastic body is provided at a position other than the bearing Can be provided.

  According to the second aspect of the present invention, the structure of the bearing provided with the viscoelastic body can be realized.

  According to the third aspect of the present invention, the distance between the image carrier and the developing roll can be increased using the developing roll without adding another member such as a ring-shaped member arranged coaxially with the developing roll. The minimum value can be regulated.

  According to the fourth aspect of the present invention, the distance between the image carrier and the developing roll can be increased using the developing roll without adding another member such as a ring-shaped member arranged coaxially with the developing roll. The maximum value can be regulated.

  According to the fifth aspect of the present invention, the material of the viscoelastic body can be embodied.

  According to the sixth aspect of the present invention, in comparison with a technique that does not have a restricting means for restricting at least one of the maximum value of the distance between the image carrier and the developing roll and the minimum value of the distance between the image carrier and the developing roll. Thus, it is possible to suppress fluctuations in the distance between the image carrier and the developing roll, and further, a developing device having a simple structure as compared with the technique in which the viscoelastic body is provided at a position other than the bearing. Can be provided.

  According to the seventh aspect of the present invention, at least one of the maximum value of the distance between the image carrier, the developing roller rotating body, and the other member and the minimum value of the distance between the image carrier and the developing roller are regulated. At this time, the structure of the apparatus can be simplified.

1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention from the front side. FIG. 2 is a cross-sectional view showing the image forming unit used in the embodiment of the present invention from the front side. FIG. 2 is a cross-sectional view schematically showing a front portion of the image forming unit used in the embodiment of the present invention from the left side. The operation of the distance regulating mechanism will be described. FIG. 4A is a diagram illustrating the distance regulating mechanism in which the distance between the image holding member and the developing roll is minimized, and FIG. 4B is a diagram illustrating the image holding member and developing. It is a figure which carries out the distance control mechanism in which the distance with a roll became the maximum. The bearing used for embodiment of this invention is shown, FIG. 5 (A) is a 1st perspective view, FIG.5 (B) is a 2nd perspective view.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 10 according to an embodiment of the present invention.

  The image forming apparatus 10 includes an image forming apparatus main body 12. A paper storage unit 14 is provided at the lower part of the image forming apparatus main body 12, and a paper discharge unit 16 is provided at the upper part of the image forming apparatus main body 12. The sheet storage unit 14 stores a large number of sheets. A paper transport path 18 is formed from the paper storage unit 14 to the paper discharge unit 16.

  The paper disposed at the top of the paper storage unit 14 is sent out by the pickup roll 20. The fed sheet is temporarily stopped by the registration roll 24 and positioned, and is conveyed to a secondary transfer roll 40 described later at a predetermined timing.

  An image forming unit 22 is provided at the center of the image forming apparatus main body 12. The image forming unit 22 includes, for example, four image forming units 26Y, 26M, 26C, and 26K. The image forming units 26 </ b> Y, 26 </ b> M, 26 </ b> C, and 26 </ b> K are provided corresponding to yellow (Y), magenta (M), cyan (C), and black (K) colors, respectively, along the intermediate transfer belt 28. Are arranged at regular intervals. The intermediate transfer belt 28 is supported by, for example, two support rolls 30 and 32 and rotates in the arrow A direction.

  Each of the image forming units 26Y, 26M, 26C, and 26K includes photosensitive drums 34Y, 34M, 34C, and 34K, which are image carriers, and developing devices 200Y, 200M, 200C, and 200K. The photosensitive drums 34Y, 34M, 34C, and 34K face the primary transfer rolls 38Y, 38M, 38C, and 38K with the intermediate transfer belt 28 interposed therebetween, and the image forming unit 26Y is formed by the primary transfer rolls 38Y, 38M, 38C, and 38K. , 26M, 26C, and 26K, the developer images are primarily transferred to the intermediate transfer belt 28.

  The secondary transfer roll 40 faces the support roll 32 with the intermediate transfer belt 28 interposed therebetween. By the secondary transfer roll 40, the developer image that has been primarily transferred is secondarily transferred onto the sheet conveyed through the sheet conveyance path 18.

  The sheet on which the developer is secondarily transferred is conveyed to the fixing device 42. The fixing device 42 is a device that fixes the toner image transferred onto the paper onto the paper using, for example, heat and pressure, and includes, for example, a heating roll 44 and a pressure roll 46. The paper on which the developer image is fixed by the fixing device 42 is discharged to the paper discharge unit 16 by the discharge roll 48.

  The image forming apparatus 10 further includes a reverse conveyance path 50. The reverse conveyance path 50 is a conveyance path for conveying the sheet on which the developer image is formed on one side to the upstream side of the registration roll 24 in the sheet conveyance path 18 while inverting the sheet. For example, two conveyance rolls 52 and 52 are arranged along the reverse conveyance path 50, and the sheet fed from the discharge roll 48 to the reverse conveyance path 50 is transferred to the sheet conveyance path 18 by the conveyance rolls 52 and 52. Be transported.

  The image forming apparatus 10 further includes a UI device 54. The UI device 54 is provided, for example, on the upper part of the image forming apparatus main body 12. The UI device 54 is configured by combining, for example, a liquid crystal display device and a touch panel type information input device, and an operator inputs setting information for image formation or displays information to the operator. Or

  The image forming apparatus 10 further includes a number of developer containers 56 corresponding to the developing devices 200Y, 200M, 200C, and 200K. A developer (toner) is stored in the developer container 56. The developer container 56 is, for example, at the upper part of the image forming apparatus main body 12 and is detachably attached to the image forming apparatus main body 12 and is attached thereto.

  The image forming apparatus 10 further includes a developer conveying device 58. The developer conveying device 58 conveys the developer of each color accommodated in the developer accommodating body 56 to the corresponding developing devices 200Y, 200M, 200C, and 200K. The developer conveying device 58 is provided with a conveying member 60 formed in a spiral shape, and the developer is conveyed from the developer container 56 to the developing devices 200Y, 200M, 200C, and 200K by rotating the conveying member 60. Is done.

  FIG. 2 shows a yellow image forming unit 26 </ b> Y as an example of the image forming unit 26. The configuration of the other image forming units 26M, 26C, and 26K is the same as that of the yellow image forming unit 26Y, and a description thereof will be omitted.

  In addition to the photosensitive drum 34Y and the developing device 200Y described above, the image forming unit 26Y irradiates the charging device 64Y that charges the photosensitive drum 34Y and the surface of the photosensitive drum 34Y that is charged by the charging device 64Y. The latent image forming device 66Y that forms a latent image on the surface of the photosensitive drum 34Y and the toner remaining on the photosensitive drum 34Y after the toner image is transferred to the intermediate transfer belt 28 by the primary transfer roll 38Y. And a cleaning device 68Y for removing and cleaning the photosensitive drum 34Y.

  The developing device 200Y is a two-component developing device that develops using toner and a carrier. The developing device 200Y includes a developing device side housing 202. The developing device side housing 202 is configured by joining an upper member 202a and a lower member 202b. Further, a developer circulation path 204 is formed in the lower part of the developing device side housing 202. A first developer conveying member 206 and a second developer conveying member 208 are disposed in the developer circulation path 204. The first developer conveying member 206 and the second developer conveying member 208 are each composed of a rotating shaft 210 and a helical stirring and conveying portion 212 formed around the rotating shaft 210. The first developer conveying member 206 and the second developer conveying member 208 are separated by a partition wall 214 formed in the central longitudinal direction. Openings (not shown) are formed on both sides in the longitudinal direction of the partition wall 214. The developer circulates in the developer circulation path 204 through the opening.

  Further, a developer supply port (not shown) connected to the developer circulation path 204 is formed in the developing device side housing 202. From this developer supply port, new toner is supplied from the developer container 56 described above via the developer transport device 58.

  The developing device 200Y has a developing roll 220. The developing roller 220 is provided to face the photosensitive drum 34Y, and performs development on the latent image on the photosensitive drum 34Y. In addition, a layer thickness regulating member 280 is provided on the upstream side of the developing region facing the photosensitive drum 34Y. The layer thickness regulating member 280 regulates the layer thickness of the magnetic brush formed on the developing roll 220. Then, the developer whose layer thickness is regulated by the layer thickness regulating member 280 is supplied to the development region, and a toner image is formed on the photosensitive drum 34Y.

  FIG. 3 is a cross-sectional view schematically showing the front portion of the image forming unit 26Y from the left side. Note that the image forming unit 26Y is symmetrical in the front-rear direction (the left-right direction in FIG. 3, the direction intersecting the paper surface in FIGS. 1 and 2), and the configuration on the rear side of the image forming unit 26Y is the configuration on the front side of the image forming unit 26Y. Since this is the same, the description thereof is omitted.

  As shown in FIG. 3, the photosensitive drum 34 </ b> Y has a drum rotation shaft 36, and is rotatably supported by the photosensitive drum side housing 92 via the drum rotation shaft 36. Here, the photosensitive drum side housing 92 and the above-described developing device side housing 202 (see also FIG. 2) can be brought close to each other by, for example, a structure such as a hinge (not shown) or the like. It can be separated.

  The developing roll 220 described above has a cylindrical member 222 as a developer holding portion and a flange member 224 mounted on the front side of the cylindrical member 222, and the outer side (right end side) of the flange member 224 is rotated. Used as a shaft 226, a roll rotation shaft 226 is rotatably attached to the developing device side housing 202 via a bearing 300 bearing 300. The cylindrical member 222 holds the developer on its outer peripheral surface.

  The flange member 224 has a large diameter portion 224a. The large diameter portion 224a has an outer diameter larger than that of the cylindrical member 222.

  The bearing 300 includes an outer ring member 310, an inner ring member 312 and a viscoelastic body 320 (see also FIG. 5). The outer ring member 310 has a ring shape, and an outer peripheral surface thereof is fixed to the developing device side housing 202.

  The inner ring member 312 has a ring shape and supports the roll rotating shaft 226 (the developing roll 220) so as to be rotatable. More specifically, the inner ring member 312 is made of a resin having low sliding resistance, the inner peripheral surface is a sliding surface, and the roll rotating shaft 226 is rotatably supported by the inner peripheral surface. Further, the inner ring member 312 is disposed inside the outer ring member 310.

  The viscoelastic body 320 is mounted so as to be sandwiched between the outer ring member 310 and the inner ring member 312. As a specific material of the viscoelastic body 320, for example, thermoplastic elastomers such as styrene, olefin, vinyl chloride, urethane, amide, etc. can be used, such as polyimide, polyethylene terephthalate, polyoxymethylene resin, Or it can comprise from the material containing any one of polyacetal resin. The outer ring member 310 and the inner ring member 312 are made of a resin that is less elastically deformed than the viscoelastic body 320. Further, the outer ring member 310, the inner ring member 312 and the viscoelastic body 320 are integrally formed.

  The image forming unit 26Y further includes a coil spring 94 used as a biasing unit. One end of the coil spring 94 is attached to the photosensitive drum side housing 92, and the other end is attached to the developing device side housing 202. The developing device side housing 202 is placed on the photosensitive drum 34Y side. Energize. In other words, the coil spring 94 urges the photosensitive drum 34 and the developing roll 220 to approach each other.

  In the image forming unit 26 </ b> Y configured as described above, when the bearing 300 moves the other of the outer ring member 310 and the inner ring member 312 while fixing one of the outer ring member 310 and the inner ring member 312, the viscoelastic body 320 is elastically deformed, and the positional relationship between the outer ring member 310 and the inner ring member 312 changes.

  Further, in the image forming unit 26Y configured as described above, the lower portion of the viscoelastic body 320 in FIG. 3 is crushed by the urging by the coil spring 94 and the own weight applied to the developing roll 220. To be deformed. Then, the developing roll 220 stops at a position where the repulsive force of the viscoelastic body 320 generated in accordance with the deformation of the viscoelastic body 320 and the own weight applied to the developing roll 220 are balanced.

  At this time, the viscoelastic body 320 is deformed in accordance with a distance G (hereinafter referred to as DRS) between the photosensitive drum 34Y and the developing roll 220. For example, when the developer enters between the photosensitive drum 34Y and the developing roll 220, the distance between the photosensitive drum 34Y and the developing roll 220 increases due to the entry of the developer, and the viscoelastic body 320 is deformed accordingly. To do.

  In the image forming unit 26 </ b> Y configured as described above, the change in the DRS is absorbed by the deformation of the viscoelastic body 320, and uneven development due to the fluctuation of the DRS is suppressed.

  On the other hand, since the image forming unit 26Y has the viscoelastic body 320, if the viscoelastic body 320 deteriorates or the viscoelastic body 320 is excessively deformed, the DRS may change greatly. There is a possibility that at least one of the maximum value and the minimum value of the DRS is not within a range desired for suppressing density unevenness. For this reason, the image forming unit 26Y has a distance regulating mechanism 800 that regulates the maximum value of DRS and the minimum value of DRS so that the DRS falls within a predetermined range. Here, the distance regulating mechanism 800 is an example of a distance regulating means.

  Although the distance regulation mechanism 800 described below regulates both the maximum value of DRS and the minimum value of DRS, the distance regulation mechanism 800 is at least one of the maximum value of DRS and the minimum value of DRS. As long as it stipulates

  The distance regulating mechanism 800 includes the above-described bearing 300 as a part of the configuration, and the above-described viscoelastic body 320 included in the above-described bearing 300 as a part of the configuration. That is, the viscoelastic body 320 included in the distance regulating mechanism 800 is provided in the bearing 300.

  FIG. 4 illustrates the operation of the distance regulating mechanism 800. FIG. 4A illustrates the distance regulating mechanism 800 in a state where the DRS is minimized, and FIG. The distance regulating mechanism 800 in a state where the DRS is maximized is shown.

  As shown in FIG. 4A, when the large-diameter portion 224a of the flange member 224 comes into contact with the photosensitive drum 34Y, the developing roll 220 is further moved from this position to the photosensitive drum 34Y even when urged by the coil spring 94. It becomes impossible to approach. At this time, the lower portion of the inner peripheral surface of the outer ring member 310 in FIG. 4A approaches the lower portion of the outer peripheral surface of the inner ring member 312 in FIG. Pushed by 312 and the outer ring member 310, the viscoelastic body 320 is deformed to contract.

  As described above, the distance regulating mechanism 800 regulates the minimum value of DRS by bringing the large diameter portion 224a of the flange member 224 of the developing roll into contact with the photosensitive drum 34Y. Note that G1 in FIG. 4A indicates the minimum value of DRS.

  As shown in FIG. 4B, when a part of the developing roll 220, more specifically, a part of the flange member 224 comes into contact with the inner peripheral surface of the outer ring member 310, the developing roll 220 is further moved from this position. It becomes impossible to move away from the photosensitive drum. As described above, the distance regulating mechanism 800 regulates the maximum value of DRS by bringing a part of the developing roll 220 into contact with the outer ring member 310. Note that G2 in FIG. 4B indicates the maximum value of DRS.

  FIG. 5 shows a bearing 300. As shown in FIG. 5, the bearing 300 includes the outer ring member 310, the inner ring member 312, and the viscoelastic body 320 described above.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 34 ... Photosensitive drum 94 ... Coil spring 200 ... Developing apparatus 220 ... Developing roll 222 ... Cylindrical member 224 ... Flange member 224a ... Large Diameter 300 ... Bearing 310 ... Outer ring member 312 ... Inner ring member 320 ... Viscoelastic body 800 ... Distance regulating mechanism

Claims (7)

An image carrier on which the latent image is developed;
A developing roll that is provided facing the image carrier and that develops the latent image of the image carrier;
A biasing means for biasing the image carrier and the developing roll so as to approach each other;
The image holding body has a viscoelastic body that deforms according to a change in distance between the image holding body and the developing roll, and the image holding body is set so that a distance between the image holding body and the developing roll is within a predetermined range. A distance regulating means for regulating at least one of a maximum value of a distance between a body and the developing roll and a minimum value of a distance between the image holding body and the developing roll;
Have
The distance regulating means has a bearing that supports the developing roll so as to rotate,
The viscoelastic body is an image forming apparatus provided on the bearing. The bearing is
An outer ring member;
An inner ring member that supports the developing roll and is disposed inside the outer ring part;
The viscoelastic body;
Have
The image forming apparatus according to claim 1, wherein the viscoelastic body is mounted so as to be sandwiched between the outer ring member and the inner ring member. The developing roll has a developer holding part for holding a developer, and a large diameter part having a larger diameter than the developer holding part,
The distance regulating means regulates a minimum value of a distance between the image holding body and the developing roll by bringing the large diameter portion into contact with the image holding body in a state where the viscoelastic body is contracted. The image forming apparatus according to 1 or 2. 4. The distance regulating unit regulates a maximum value of a distance between the image carrier and the developing roll by bringing a part of the developing roll into contact with the outer ring member. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the viscoelastic body is made of a material including any one of polyimide, polyethylene terephthalate, polyoxymethylene resin, and polyacetal resin. A developing roll that is provided opposite to an image carrier on which the latent image is developed, and that develops the latent image on the image carrier;
A biasing means for biasing the image carrier and the developing roll so as to approach each other;
The image holding body has a viscoelastic body that deforms according to a change in distance between the image holding body and the developing roll, and the image holding body is set so that a distance between the image holding body and the developing roll is within a predetermined range. A distance regulating means for regulating at least one of a maximum value of a distance between a body and the developing roll and a minimum value of a distance between the image holding body and the developing roll;
Have
The distance regulating means has a bearing that supports the developing roll so as to rotate,
The viscoelastic body is a developing device provided in the bearing. The maximum value of the distance between the developing roll and the image carrier and the developing roll so that the distance between the developing roller and the image carrier facing the developing roller is within a predetermined range. A bearing used to regulate at least one of the minimum values of the distance between the image carrier and the image carrier,
The bearing is
An outer ring member;
An inner ring member that supports the rotating body and is disposed inside the outer ring member;
A viscoelastic body that is mounted between the outer ring member and the inner ring member and deforms in accordance with a change in positional relationship between the outer ring member and the inner ring member;
Bearing.

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