JP5653071B2 - Development device - Google Patents

Description

The present invention is provided in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile, or a composite machine using an electrophotographic system or an electrostatic recording system, and a developer for a latent image formed on an image carrier. the by adhering relates to a developing device for a visible image.

  2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic method generally charges the surface of a drum-shaped photoconductor, which is an image carrier, uniformly by a charger, and the charged photoconductor is converted into image information by an exposure device. In response to the exposure, an electrostatic latent image is formed on the photoreceptor. The electrostatic latent image formed on the photosensitive member is visualized as a toner image by a toner as a developer using a developing device. The visualized image is transferred to a recording material by a transfer device. Thereafter, the toner image transferred onto the recording material is melted and fixed onto the recording material S by heat and pressure by a fixing device.

  As such a developing apparatus, there is one that uses a two-component developer including non-magnetic toner particles (toner) as a developer and magnetic carrier particles (carrier). In the developing device using the two-component developer, the toner and the carrier are conveyed in the developing container while being agitated, and the developer is carried on the developing sleeve which is a developer carrying member. The carrying amount of the developer carried on the developing sleeve is regulated by a regulating blade that is a developer regulating member. Thereafter, by applying a developing bias between the developing sleeve and the photosensitive member, only the toner is transferred to the electrostatic latent image formed on the surface of the photosensitive member, and a toner image corresponding to the electrostatic latent image is formed on the surface of the photosensitive member. Is formed.

  Also known is a twin-sleeve type developing device that uses two developing sleeves in order to increase the exposed area of the developing sleeve to the photosensitive member. In the case of such a twin-sleeve type developing device, since the exposed area of the developing sleeve can be increased, higher speed and higher image quality can be realized than a structure with a single developing sleeve.

  However, in the case of the twin sleeve system, the amount of scattered toner increases because the exposed area of the developing sleeve is large. For example, the developer is likely to be ejected from between two developing sleeves that rotate in the counter direction. In addition, the developing sleeve forms irregularities on the surface of the intermediate portion to make it easier to carry the developer, while the surface roughness of both end portions (metal ring portions) is made smaller than that of the intermediate portion so that the developer is at both end portions. Although it is suppressed from being carried, a large amount of toner may protrude from the metal ring portion. Such protrusion of the toner to the metal ring portion can occur even with a single developing sleeve. In any case, a large amount of scattered toner is not preferable because it easily causes in-machine contamination and image defects.

  In order to suppress such scattered toner, a technique for sealing a part of the developing sleeve facing the photosensitive drum has been conventionally known (see, for example, Patent Documents 1 to 5). Patent Documents 1 to 5 describe a structure in which a non-development area at the end of the opening of the developing container is sealed with a sheet in order to suppress toner leakage at the end of the developing sleeve.

JP 2002-268379 A JP2007-232815A JP 2008-129140 A Japanese Patent Laid-Open No. 2-101486 JP-A-9-319215

  As described above, the sheet for preventing toner scattering is disposed between the developing sleeve and the photosensitive drum. Since the developing sleeve and the photosensitive drum are disposed in close proximity to each other (via a gap), both surfaces of the sheet disposed in the gap are in proximity to or in contact with the developing sleeve and the photosensitive drum, respectively. When the developing sleeve and the photosensitive drum are rotated to form an image in such a state, both surfaces of the sheet are rubbed against the developing sleeve and the photosensitive drum, and the sheet is pulled in the rotation direction. Therefore, if the sliding resistance between the both surfaces of the sheet and the developing sleeve and the photosensitive drum is large, the sheet is pulled strongly, the sheet is loosened and the sliding resistance is further increased, or the sheet is further damaged. There is a possibility. When the sheet is broken, toner scattering cannot be sufficiently suppressed, and in-machine contamination and image defects are likely to occur.

  In particular, when the sheet becomes weak, such as in a high-temperature and high-humidity environment, the sheet stiffness is lost against the rubbing resistance, and the sheet is easily damaged. In addition, in the case of a configuration in which the sheet comes into contact with the surface of the developing sleeve or a configuration in which the sheet comes into contact with the developing sleeve due to the weight of the sheet, the influence of rubbing with the developing sleeve becomes large.

In view of such circumstances, the present invention is designed to realize a structure capable of reducing the sliding resistance between a cover member such as a sheet and a developer carrying member and suppressing a decrease in the durable life of the cover member. It is a thing.

The present invention provides a developer container that contains a two-component developer composed of a non-magnetic toner and a magnetic carrier, and an opening that faces the image carrier of the developer container and carries the developer. A developer carrying member to be conveyed , and at least a part of both surfaces thereof are arranged to face the developer carrying member and the image carrier , respectively , and the developer carrying member conveys the developer; A sheet member attached to the developing container so as to cover the widthwise end of the developer carrying member orthogonal to the end of the opening of the developing container, and the sheet member and the developer The sheet member is subjected to a treatment for interposing a toner before the initial driving of the apparatus, and the sheet member has an average height of irregularities on the surface on the developer carrier side than on the surface on the image carrier side. On both sides to be lower Lying in a developing device according to claim in which roughening treatment is performed.

According to the present invention, since the toner is interposed between the sheet member and the developer carrier before the initial driving of the apparatus, the frictional resistance between the sheet member and the developer carrier is reduced. And the fall of the durable life of a sheet | seat member can be suppressed.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2A is a diagram of a developing device according to the present embodiment, in which FIG. 1A is a view of a part of the developing device viewed from the photosensitive drum side, and FIG. FIG. 3 is a schematic configuration diagram showing a developing device in a cut state in order to explain the movement of the developer. FIG. 4A is a cross-sectional view perpendicular to the rotation axis, showing a part of the developing device cut and viewed from the photosensitive drum side, and FIG. The sheet which concerns on this embodiment is shown, (A) is a schematic plan view, (B) is sectional drawing which expanded a part, (C) And (D) is a schematic plan view which shows another example from which a surface shape differs, respectively. .

  An embodiment of the present invention will be described with reference to FIGS. 1 to 5. First, an outline of the image forming apparatus of the present embodiment will be described with reference to FIG. In the following description, a tandem type image forming apparatus that forms a full-color image will be described as an example of the image forming apparatus. However, it goes without saying that the present invention can be applied to other image forming apparatuses.

[Image forming apparatus]
As shown in FIG. 1, the image forming apparatus 100 includes stations PY, PM, PC, and PK for each color of Y (yellow), M (magenta), C (cyan), and K (black). . Each station has substantially the same configuration, and a full-color image forms an image of each color of Y, M, C, and K, respectively. In FIG. 1, Y, M, C, and K are added to the reference numerals of the components of each station, but the subscripts are omitted in the following description. Therefore, for example, if the developing device 4 is used, the developing device 4Y, the developing device 4M, the developing device 4C, and the developing device 4K in each of the Y, M, C, and K stations are commonly referred to.

  The photosensitive drum 1 as an image carrier is rotatably provided, and the surface of the photosensitive drum 1 is covered with charged particles accompanying the discharge of the primary charger 2 as a corona charger (which may be a charging roller). It is charged like this. Thereafter, the uniformly charged surface of the photosensitive drum 1 is exposed to light modulated in accordance with an information signal by a light-emitting element 3 as a latent image forming unit such as a laser to discharge a dark part potential, thereby exposing the photosensitive drum. An electrostatic latent image is formed on the surface of the drum 1. The electrostatic latent image formed in this way is visualized on the photosensitive drum 1 as a toner image by the developing device 4.

  Next, the toner image is transferred to the intermediate transfer belt 25 that is an intermediate transfer member at the primary transfer portion T by applying a primary transfer bias from the power source D1 to the primary transfer roller 5 that is a primary transfer unit. At this time, the intermediate transfer belt 25 rotates, and the toner images are sequentially stacked at each station. Then, the toner images on which the respective colors are superimposed are conveyed to the secondary transfer portion T2, and a secondary transfer bias is applied from the power source D2 between the secondary transfer inner roller 23 and the secondary transfer outer roller 14. At this time, all the colors are secondarily transferred collectively to the recording material P conveyed to the secondary transfer portion T2 in synchronization with the toner image.

  The recording material P on which the toner image is placed is conveyed to the fixing device 7, and the toner image is fixed on the recording material P by the fixing device 7. On the other hand, the transfer residual toner on the photosensitive drum 1 is removed by the cleaning device 6, and the transfer residual toner on the intermediate transfer belt 25 is removed by the belt cleaning device 26. Further, the toner consumed in the image formation is supplied to the developing device 4 from the toner supply tank.

  The recording material P is pulled out from the paper feed cassette 10 by the pickup roller 11, separated one by one by the paper feed separation device 12, and sent to the registration roller 13. The registration roller 13 receives and waits for the recording material P in the stopped state, and sends the recording material P to the secondary transfer portion T2 in time with the toner image carried on the intermediate transfer belt 25. The intermediate transfer belt 25 is supported around the tension roller 21, the drive roller 22, and the secondary transfer inner roller 23, and is driven by the drive roller 22 to rotate in the direction of arrow R2.

[Developer]
Next, the developing device 4 of this embodiment will be described with reference to FIGS. As shown in FIG. 2, the developing device 4 includes a developing container 40, developing sleeves 41 and 43 that are developer carrying members, each of which constitutes a developer carrying member, and a sheet 70 that is a sheet member . The developing container 40 contains a two-component developer composed of a nonmagnetic toner and a magnetic carrier. Further, the developing container 40 has a divided supply chamber 47 and a stirring chamber 48, and a supply screw 45 is arranged in the supply chamber 47 and a stirring screw 46 is arranged in the stirring chamber 48. Each of these screws 45 and 46 is rotationally driven, and conveys the developer in opposite directions while stirring the developer.

  In the case of this embodiment, the supply chamber 47 and the stirring chamber 48 are arranged so as to be lined up and down, and a replenishment developer (which may mainly contain toner and carrier) is supplied to the lower stirring chamber 48. A developer supply port 50 is provided. A developer discharge port 49 is provided in the upper supply chamber 47. Further, both end portions of both the chambers 47 and 48 are communicated so that the developer is transferred between the two chambers, thereby constituting a developer circulation path.

  Further, the developing sleeves 41 and 43 are disposed so as to be able to rotate and drive closer to the photosensitive drum 1 side than both the chambers 47 and 48 of the developing container 40, and a part of the surface of both the sleeves 41 and 43 from the opening 40 a of the developing container 40. Is exposed. The pair of developing sleeves 41 and 43 are arranged so that the rotation axes thereof are parallel to each other and with a gap in the rotation direction of the photosensitive drum 1. That is, the pair of developing sleeves 41 and 43 are arranged with a gap therebetween so as to be aligned vertically along the rotation direction of the photosensitive drum 1. Further, the rotation shafts of the developing sleeves 41 and 43 are arranged in parallel with the rotation shaft of the photosensitive drum 1.

  Magnets 42 and 44, which are multipolar magnets, are disposed in the developing sleeves 41 and 43, respectively. These magnets 42 and 44 are fixed to the developing container 40 so as not to rotate. The magnets 42 and 44 have a plurality of N poles and S poles alternately arranged in the rotation direction of the developing sleeves 41 and 43, and have no magnetic poles on a part opposite to the surface facing the photosensitive drum 1. It is configured.

  As shown in FIG. 3, the developing device 4 configured as described above increases the toner ratio through the developer supply port 50 disposed at the end of the developing container 40 positioned upstream in the transport direction of the stirring screw 46. The replenishment developer is supplied to the stirring chamber 48. The agitation screw 46 mixes the replenishing developer supplied through the developer supply port 50 with the circulating developer in the process of conveying the developer in the axial direction and circulating it to the supply chamber 47. At the same time, the developer separated from the lower developing sleeve 43 remaining after the development and returned to the stirring chamber 48 is taken into the circulating developer and mixed. The supply screw 45 uniformly supplies the charged developer along the longitudinal direction of the upper developing sleeve 41 in the process of conveying the developer in the axial direction and circulating it to the stirring chamber 48. Through the developer discharge port 49 disposed at the end of the developer container 40 located on the downstream side of the supply screw 45 in the conveying direction, a part of the circulating developer overflows and is discharged as having reduced charging performance. Yes.

  Development of the electrostatic latent image formed on the photosensitive drum 1 by the developing device 4 is performed as follows. First, the developer is stirred while being conveyed in a direction perpendicular to the paper surface of FIG. 3 by the supply screw 45 and the stirring screw 46, and the non-magnetic toner is charged to the negative polarity and the magnetic carrier is charged to the positive polarity. The charged two-component developer is carried on the developing sleeves 41 and 43 rotating around the magnets 42 and 44 in a stand-up state and rubs the photosensitive drum 1. The power source D4 applies, to the developing sleeves 41 and 43, an oscillating voltage obtained by superimposing a rectangular AC voltage having a frequency of 8.0 kHz and a peak-to-peak voltage Vpp of 1.8 kV on a negative DC voltage Vdc (for example, −350 V). Apply. As a result, the negatively charged toner moves to the electrostatic latent image on the photosensitive drum 1 that is relatively positive with respect to the developing sleeves 41 and 43 by the DC voltage Vdc, and the electrostatic latent The image is reversed and developed with toner.

  The movement of the developer ni at this time will be described with reference to FIG. The toner in the developer ni conveyed to the surface facing the photosensitive drum 1 by the developing sleeve 41 receives an electric force due to a potential difference between the electrostatic latent image on the photosensitive drum 1 and the developing sleeve 41, and the developing sleeve 41 receives the electric force from the developing sleeve 41. Fly towards 1. More specifically, the toner reciprocates in the facing distance (gap) between the developing sleeve 41 and the photosensitive drum 1 by the AC voltage applied to the developing sleeve 41. The negatively charged toner moves according to the potential difference between the DC voltage Vdc applied to the developing sleeve 41 and the electrostatic image while reciprocating. As a result, toner returns to the developing sleeve 41 in the dark portion potential VD region, and an amount of toner corresponding to the potential difference adheres to the photosensitive drum 1 in the bright portion potential VL region.

  The developer ni carried on the upper developing sleeve 41 is moved downward along the magnetic force lines of the magnets 42 and 44 formed in a region where the developing sleeve 41 and the lower developing sleeve 43 are opposed to each other. Move to. Since there is no magnetic pole downstream of the N3 magnetic pole of the magnet 42 in the rotation direction, the two-component developer ni is peeled off from the developing sleeve 41 at this portion. The peeled two-component developer ni is attracted to the S3 magnetic pole of the magnet 44 and is mounted on the developing sleeve 43.

  The developer ni toner conveyed again to the surface facing the photosensitive drum 1 by the developing sleeve 43 receives an electric force due to a potential difference between the electrostatic image of the photosensitive drum 1 and the developing sleeve 43, and the developing sleeve 43 receives the electric force from the developing sleeve 43. Fly towards. The toner reciprocates at a distance facing the photosensitive drum 1 by the AC voltage applied to the developing sleeve 43, and an amount corresponding to the potential difference between the DC voltage Vdc applied to the developing sleeve 43 and the electrostatic image is applied to the photosensitive drum 1. Adhere to. The developer ni in which a part of the toner is consumed by the development is carried on the developing sleeve 43 and rotated, and is collected again in the developing container 40 and returned to the stirring chamber 48.

[Surface properties of development sleeve]
As described above, the developing sleeves 41 and 43 for carrying and transporting the developer carry the carrying portions 41a and 43a carrying the developer at the axially intermediate portion, and carry the developer at both axial ends than the carrying portions 41a and 43a. Non-supporting portions 41b and 43b that are difficult to perform are provided. The support portions 41a and 43a are portions where irregularities are formed on the surfaces of the developing sleeves 41 and 43 formed in a cylindrical shape with a metal such as an aluminum alloy or stainless steel, for example. The developer is carried on the developing sleeves 41 and 43 by being held on the uneven portions. The non-supporting portions 41b and 43b are portions (metal ring portions) that are not subjected to blasting as described above and have a surface roughness smaller than that of the supporting portions 41a and 43a.

  Since the non-carrying portions 41 b and 43 b are not formed with irregularities, it is difficult to hold the developer, and even if the developer is adsorbed by the magnets 42 and 44, the developer is carried by the rotation of the developing sleeves 41 and 43. Without being carried away from the non-supporting parts 41b and 43b. The non-carrying parts 41 b and 43 b are arranged in a non-image forming area that is out of the image forming area of the photosensitive drum 1. Since the developing sleeves 41 and 43 have the supporting portions 41a and 43a and the non-supporting portions 41b and 43b as described above, the developer is positively conveyed by the supporting portions 41a and 43a, and the non-supporting portions 41b and 43b develop. The agent is not transported.

[Magnetic seal]
Further, in the developing device 4 of the present embodiment, magnetic seals 51 and 52 are arranged at both axial ends of the developing sleeves 41 and 43, respectively. The configuration of this part will be described with reference to FIG. As shown in FIG. 4B, the magnetic seals 51 and 52 are formed by bending a band-shaped magnet member having magnetic poles on the surface. Such magnetic seals 51 and 52 are arranged so as to cover the opposite sides of the non-carrying portions 41b and 43b of the developing sleeves 41 and 43 in the axial direction at the opposite sides to the photosensitive drum 1, respectively.

  As shown in FIG. 4A, the magnetic seal 51 disposed at the end of the developing sleeve 41 forms a magnetic spike H of developer on the surface to fill the gap between the magnetic seal 51 and the developing sleeve 41. ing. As a result, the two-component developer moves in the axial direction through the gap between the magnetic seal 51 and the developing sleeve 41 to prevent the developer from adhering to the end of the developing sleeve 41 or leaking from the developing container 40. Yes.

Thus, by the magnetic spike H formed on the magnetic seal 51, the developer carrying region A1 in the developing sleeve 41 {the portion indicated by the oblique lines in FIG. 2A and FIG. 4A} is in the longitudinal direction (axial direction , Limited in the width direction ). After that, the developer carried on the carrying area A1 passes through the developing area A2 facing the photosensitive drum 1 (the portion indicated by the diagonal lattices in FIGS. 2A and 4A), and then the developing sleeve 41 and the developing sleeve. It is conveyed to 43 gap G1. In the gap G <b> 1, the developer moves so that the magnetic spike H formed on the developing sleeve 41 is pulled out and transferred to the developing sleeve 43.

  At this time, the developer moves with a rapid change of direction between the developing sleeve 41 and the developing sleeve 43 whose surface moves in the counter direction, and therefore, the developer is removed in the gap G1 between the developing sleeve 41 and the developing sleeve 43. Spreads outward slightly. For this reason, the developer carrying region A3 in the developing sleeve 43 {the portion indicated by the oblique lines in FIG. 2A and FIG. 4A} is outside in the longitudinal direction from the developer carrying region A1 in the developing sleeve 41 ( Widened to the end side). The developer carried on the carrying area A3 is then transported to the developing area A4 (the portion indicated by the diagonal grids in FIGS. 2A and 4A) facing the photosensitive drum 1.

  Further, in the gap G1, since the developer moves with a sudden change of direction, a very small amount of the developer scatters along the gap G1 to the gap G2 outside the longitudinal direction of the two-component developer carrying region. A part of the two-component developer in the gap G2 is scattered from the gap G2 toward the photosensitive drum 1 by the rotating developing sleeve 43.

  On the other hand, as shown in FIG. 4A, the magnetic seal 52 disposed at the end of the developing sleeve 43 also forms a magnetic head H of the developer on the surface, and the magnet 44 slides in a range where the magnetic pole does not have a magnetic pole. The developer that rubs around the developing sleeve 43 is removed. Further, the gap between the magnetic seal 52 and the developing sleeve 43 is filled with the magnetic spike H to prevent the developer from moving in the axial direction toward the end of the developing sleeve 43. As shown in FIG. 4B, the ends of the magnetic seals 51 and 52 near the gap G2 between the developing sleeves 41 and 43 have the same polarity as the S3 magnetic pole facing the gap G2 of the magnet 44 on the downstream side. It is said. As a result, a repulsive magnetic field is formed between the end of the magnetic seal 52 on the gap G2 side and the S3 magnetic pole of the magnet 44, and the developer that rotates around the developing sleeve 43 is conveyed to the gap G2 between the developing sleeves 41 and 43. Is suppressed.

  By providing the magnetic seals 51 and 52 as described above, the two-component developer is prevented from leaking from the developing container 40 through the gap G2 outside the carrying areas A1 and A2. However, the magnetic countermeasure for suppressing the leakage of the developer from the developing container 40 through the gap G2 is not limited to such a magnetic pole arrangement.

  However, even if the magnetic seals 51 and 52 are provided in this way, the developer cannot be sufficiently prevented from leaking from the gap G2 between the developing sleeves 41 and 43 outside the carrying regions A1 and A3. In the present embodiment, the sheet 70 is provided for this purpose, but a case where the sheet 70 is not provided will be described.

  When a large amount of image formation is performed over a long period of time, as shown in FIG. 3, on the guide member 53 on which the developing device 4 is mounted, a position immediately below the carrying areas A1 and A3 of the developing sleeves 41 and 43, Developer ni is deposited like an anthill. The deposited developer ni is separated into a non-magnetic toner and a magnetic carrier when the charged charge is attenuated. For this reason, for example, when the developing device 4 is detachably attached to the image forming apparatus 100 as a toner cartridge, fine non-magnetic toner is scattered around by a slight wind generated when the developing device 4 is pulled out. Then, the deposited developer spreads inward in the longitudinal direction, falls on the intermediate transfer belt 25, and stains the image.

  Further, the toner carried along with the rotation of the photosensitive drum 1 reaches the cleaning device 6 shown in FIG. 1 and stains the region outside in the longitudinal direction from the cleaning blade. For this reason, it is dammed by the side seal installed outside the cleaning blade and falls, and accumulates like a anthill on the guide member on which the cleaning device 6 is mounted. Also in this case, the image is spread on the guide member toward the inner side in the longitudinal direction and falls on the intermediate transfer belt 25 to contaminate the image. Further, a part of the toner passes through the cleaning device 6 and reaches the primary charger 2, and the shield plate and grid of the charger 2 are soiled, resulting in an increase in maintenance frequency.

  As shown in FIG. 4A, more two-component developer is scattered from the gap G2 outside the carrying areas A1 and A3 than from the gap G1 between the carrying areas A1 and A3 to the photosensitive drum 1 side. To do. Further, there is a possibility that the non-magnetic toner resulting from the leakage of the two-component developer is brought to the photosensitive drum 1 and causes unnecessary toner contamination around the end of the photosensitive drum 1.

[Sheet]
In this embodiment, in order to prevent the developer from leaking from the developer container 40, the outer sides of the developer carrying areas A1 and A3 of the developing sleeves 41 and 43 are covered with the sheet 70 that is a sheet member , and the gap G2 The leaked developer is confined in the developing device 4. After the developer leaking from the gap G <b> 2 is captured by the sheet 70, it is collected into the developing container 40 by utilizing the rotation of the developing sleeve 43.

  Such a sheet 70 will be described in detail with reference to FIGS. The sheet 70 which is a cover member is a resin material such as polyurethane formed in a film shape, and is disposed so as to cover a part of the developing sleeves 41 and 43 facing the photosensitive drum 1. In the arrangement state, both surfaces of the sheet 70 are close to or in contact with the developing sleeves 41 and 43 and the photosensitive drum 1. In the case of this embodiment, the sheet 70 is disposed so as to cover the gap G2 between the non-carrying portions of at least one pair of the developing sleeves 41 and 43.

Specifically, among the openings 40a of the developing container 40 facing the photosensitive drum 1, the developing sleeves 41 and 43 have the non-carrying portions 41b and 43b, and the developing sleeves 41 and 43 convey the developer. The sheet 70 is fixed so as to cover both ends in the orthogonal axial direction (width direction) . For this purpose, the sheet 70 is formed in a strip shape having a predetermined length, and both ends in the longitudinal direction constitute an upper frame 40b1 on the upper side of the developing sleeve 41 and a lower frame on the lower side of the developing sleeve 43 constituting the developing container 40. It is fixed to (attached to) 40b2. Therefore, the sheet 70 is arranged so as to be spanned between the upper frame 40b1 and the lower frame 40b2, and covers the portion between the two frames 40b1 and 40b2 in the opening 40a (the end of the opening 40a is sealed). )

  Further, the portions of the developing sleeves 41 and 43 that face the photosensitive drum 1 slightly protrude from the opening 40a. Therefore, the sheet 70 is disposed so as to be wound around a portion of the developing sleeves 41 and 43 that faces the photosensitive drum 1 and a part thereof is in contact with its own weight. For this reason, the length of the sheet 70 is set in consideration of the winding angle.

  Further, the side portion 70 a of the sheet 70 on the end portion side of the developing container 40 covers the horizontal frame 40 b 3 constituting both end portions in the axial direction of the developing container 40. Then, at least a portion located between the developing sleeves 41 and 43 of the side portion 70a of the sheet 70 is fixed to the horizontal frame 40b3 by bonding or the like. This prevents the sheet 70 from slacking while maintaining a predetermined wrap angle with respect to the developing sleeves 41 and 43, and makes the entire side portion 70a easily adhere to the horizontal frame 40b3. Note that the entire side portion 70a may be bonded to the horizontal frame 40b3. On the other hand, the side portion 70b on the center side of the developer container 40 of the sheet 70 is as much as possible within a range where it does not come into contact with the developer carrying area A3 diffused outward as the developer is transferred from the developing sleeve 41 to the developing sleeve 43. Closely positioned.

Such a sheet | seat 70 forms the shape of both surfaces in an unevenness | corrugation (texture), respectively, and as shown to FIG. In other words, the surface roughness of both surfaces of the sheet 70 is roughened (roughening treatment is performed) . As shown in FIG. 5B, the height of the unevenness is set such that the total t of the average heights of the unevenness on both surfaces is, for example, 100 μm or less.

Further, the unevenness on both surfaces of the sheet 70 is formed such that the surface 71 facing the photosensitive drum 1 has a smaller frictional resistance at the time of contact than the surface 72 facing the developing sleeves 41 and 43. . Specifically, the surface 71 of the sheet 70 facing the photosensitive drum 1 is rougher than the surface 72 facing the developing sleeves 41 and 43. For this purpose, for example, the (average) height of the unevenness formed on the surface 71 is made larger than the (average) height of the unevenness formed on the surface 72 (in other words, the surface on the developing sleeve 41, 43 side is more photosensitive. The average height of the unevenness is made lower than the surface on the drum 1 side) , and the number of unevenness of the surface 71 is made smaller than the number of unevenness of the surface 72.

  The reason why the friction resistance of the surface 71 is made smaller than that of the surface 72 in this way is as follows. That is, since the developing sleeves 41 and 43 are made of a metal such as an aluminum alloy or stainless steel, the sheet 70 that is a resin material is in contact with the metal and the resin, and the frictional resistance is relatively small. On the other hand, since the photosensitive drum 1 has a resin coating on the surface of a tube made of, for example, an aluminum alloy, the sheet 70 comes into contact with the resin and the frictional resistance becomes relatively large. Therefore, in the present embodiment, the surface resistance of the sheet 70 facing the photosensitive drum 1 of the sheet 70 having a relatively large rubbing resistance is increased, and the contact area with the photosensitive drum 1 is decreased, thereby reducing the rubbing resistance. We are trying to reduce it.

  As described above, in order to form irregularities on the surface of the sheet 70, for example, there are the following methods. That is, a sheet of paper such as thick paper formed on the surface shape unevenness is brought into close contact with the surface of a thin resin film (for example, about 100 μm thick) whose surface shape is not formed unevenly, and is thickened by applying pressure. The unevenness formed on the sheet is transferred to the surface of the resin fill. Alternatively, the surface of the resin film is brought into close contact with a roller made of a metal having sufficient irregularities on the surface shape or a synthetic resin having sufficient rigidity, and the film is rotated while being sandwiched between the rollers facing each other. The unevenness on the surface of the roller is transferred to the surface of the resin film. In any case, the surface of the thick sheet or roller is formed so as to have the desired unevenness to be formed on the surface of the sheet 70, and the desired surface is transferred by transferring the unevenness to the thin resin film. A sheet 70 having properties is obtained.

  The unevenness formed on the surface of the sheet 70 may be other than the matte shape as shown in FIG. For example, as shown in FIG. 5C, unevenness may be formed in parallel with the longitudinal direction of the sheet 70, or as shown in FIG. 5D, it may be formed in a mesh shape. In any case, any shape that reduces the contact area with the mating member may be used. In addition, it is preferable to reduce the contact area by making the shape of the tip of the protrusion constituting the projections as sharp as possible.

In the case of the present embodiment, toner is applied in advance (before the initial driving of the apparatus) to the surface 72 of the sheet 70 facing the developing sleeves 41 and 43. As a result, the toner is carried on the unevenness formed on the surface 72 of the sheet 70, and the toner is interposed between the developing sleeves 41 and 43 and the sheet 70 in a state where the sheet 70 is disposed at a predetermined position of the developing container 40. I have to. In other words, a process of interposing toner is performed between the sheet 70 and the developing sleeves 41 and 43 in advance. Since the sheet 70 faces the non-carrying portions 41b and 43b of the developing sleeves 41 and 43, the toner may be applied to the non-carrying portions 41b and 43b in advance. Further, it is preferable that the toner to be applied in accordance with the color of the station to be used, but if it is not known which station is used at the stage of applying the toner, it is colorless. It is preferable to use a clear toner.

[Effect of the embodiment]
In the case of the present embodiment configured as described above, the sheet 70 is disposed so as to cover a portion including the gap G2 on the outer side in the axial direction of the developer carrying areas A1 and A3 of the developing sleeves 41 and 43. It is possible to suppress the developer leaking from the outside from being scattered by the sheet 70. The developer that jumps out of the gap G <b> 2 collides with the sheet 70 and is guided to the developing container 40 along the rotation direction of the lower developing sleeve 43. Here, as shown in FIG. 2B, the sheet 70 is disposed so as to be wound around the sleeves 41 and 43 so as to enter and exit along a contour perpendicular to the rotation direction of the developing sleeves 41 and 43. . Further, the side portion 70a of the sheet 70 is in close contact with the horizontal frame 40b3. Therefore, it is possible to sufficiently suppress the developer jumping out from the gap G2 as described above from leaking out of the developing container 40.

  Further, the sheet 70 is disposed so as to be wound around the developing sleeves 41 and 43 as described above, and is in close proximity to the photosensitive drum 1. The gap between the developing sleeves 41 and 43 and the photosensitive drum 1 is, for example, about 300 to 500 μm, and the thickness of the sheet 70 disposed in this gap is about 100 μm. For this reason, the sheet 70 and the photosensitive drum 1 are almost in contact with each other. During image formation, the upper and lower developing sleeves 41 and 43 and the photosensitive drum 1 are rotated in the directions of R3 and R1, respectively. Therefore, the sheet 70 is constantly pulled in the rotational direction by the developing sleeves 41 and 43 and the photosensitive drum 1. ing. In particular, the sheet 70 has a large winding angle around the upper sleeve 41.

  On the other hand, in the case of the present embodiment, the shapes of both surfaces of the sheet 70 are formed to be uneven, so that when both surfaces come into contact with the developing sleeves 41 and 43 and the photosensitive drum 1, the shapes of both surfaces are formed. A contact area can be made smaller than the structure which is not formed in unevenness. Further, the sliding resistance at the time of contact between both surfaces, the developing sleeves 41 and 43 and the photosensitive drum 1 can be reduced, and the decrease in the durable life of the sheet 70 can be suppressed.

  Further, by forming the shapes of both surfaces of the sheet 70 to be uneven, the toner powder that adheres to the metal ring portions (non-supporting portions 41 b and 43 b) of the developing sleeves 41 and 43 when the developing device 4 is operated can be removed at the uneven portions. Hold (support). Thus, toner can be interposed between the developing sleeves 41 and 43 and the sheet 70 to reduce the chance that the sheet 70 and the developing sleeves 41 and 43 are in direct contact with each other. The sliding resistance can be further reduced.

In the case of this embodiment, since the toner is applied to the sheet 70 in advance and the toner is interposed between the developing sleeves 41 and 43 and the sheet 70, the annular portion is caused by the operation of the developing device 4 as described above. The rubbing resistance can be reduced even in the initial state where the amount of toner adhering to the toner is small. That is, in the initial state (when the product is shipped, for example , before the initial driving of the apparatus ), the toner is not conveyed between the non-carrying portions 41b and 43b and the sheet 70. It will be operated in the state without. Then, the rubbing resistance between the developing sleeves 41 and 43 and the sheet 70 increases, and the damage received by the sheet 70 increases. On the other hand, if the toner is present in the initial state as in the present embodiment, such damage to the sheet 70 can be reduced.

  Although it is conceivable that the unevenness formed on the sheet 70 is formed on the metal ring part side of the developing sleeves 41 and 43 as described above, there is a possibility that developer leakage and image defects may occur when the metal ring part is formed with unevenness. is there. That is, as described above, the outer peripheral surface of the intermediate portion of the developing sleeves 41 and 43 has already been shaped (blasted) for carrying and transporting the developer. The developer is conveyed as the outer peripheral blast uneven surface of the developing sleeves 41 and 43 rotates. On the other hand, the developer transportability of the sleeve surface is eliminated by not blasting the metal ring corresponding to the non-image area at the end of the developing sleeves 41 and 43. Therefore, if the blast processing is applied to the metal ring portion, the developer may be positively conveyed to cause a developer leakage or an image defect.

[Another embodiment]
In the above-described embodiment, the present invention is applied to a twin-sleeve developing device. However, the present invention can also be applied to a structure with one developing sleeve. In this case, the developer carrying member is constituted by the single developing sleeve. That is, a sheet as a sheet member is provided at a position opposite to the metal ring at both ends in the axial direction of one developing sleeve that is rotatably supported by the developing container, and the shape of both surfaces of the sheet is formed to be uneven. .

  Further, the position where the sheet is provided is not limited to a position facing both ends of the developer carrying member, but can also be disposed at a position where the developer may leak from the developing container. In short, it suffices if the developer carrier and the image carrier are partially covered with a sheet so that the developer can be prevented from leaking from the developer container.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum (image carrier), 4 ... Developing device, 40 ... Developer container, 41, 43 ... Developer sleeve (Developer carrier, developer carrier), 41a, 43a ..Supporting parts, 41b, 43b ... non-supporting parts, 70 ... sheet ( sheet member )

Claims (2)

A developer container containing a two-component developer composed of a non-magnetic toner and a magnetic carrier;
A developer carrier disposed in an opening facing the image carrier of the developer container and carrying and transporting the developer;
At least a part of both surfaces of the developer carrier and the image carrier are arranged so as to face each other , and the developer carrier is perpendicular to a direction in which the developer carrier transports the developer. A sheet member attached to the developing container so as to cover an end in the width direction and sealing an end of the opening of the developing container ,
The sheet member is subjected to a process of interposing toner before the initial driving of the apparatus between the sheet member and the developer carrier, and the surface of the sheet member on the developer carrier side is closer to the surface on the image carrier side. Roughening treatment is applied to both sides so that the average height of the unevenness is lower than
A developing device. The surface on the developer carrier side of the cover member is capable of carrying toner on the surface by being subjected to the roughening treatment .
The developing device according to claim 1.

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