JP2009151103A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that there is possibility that an image defect is caused by intrusion of developer into an area between first and second developing sleeves. <P>SOLUTION: A developing device includes: first and second developer carriers for developing electrostatic latent images; first and second magnetic field generating means disposed in respective developer carriers; a developer container that rotatably supports the first and second developer carriers; and a restricting member that restricts developer from entering an area which is inside of the developing machine and is between the first and second developer carriers extending adjacent to each other, wherein part in longitudinal direction is provided with a low restricting area where a restricting force is weaker than that in the other area. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is used for an image forming apparatus such as a copying machine or a laser beam printer using an electrophotographic method or an electrostatic recording method in which a developer is attached to a latent image formed on an image carrier to make a visible image. It relates to a developing device.

  In image forming apparatuses such as electrophotographic copying machines, conventionally, developing apparatuses applied to these image forming apparatuses are known by a powder cloud method, a cascade method, a magnetic brush method, etc. Among these, two-component development is known. In the case of the magnetic brush method, a two-component developer containing a mixture of magnetic carrier, toner, etc. is adsorbed to the magnetic field generating means, and the developer is raised in a brush shape at the magnetic pole portion, and then on the photosensitive drum. The electrostatic latent image is developed by rubbing to form an image. At this time, since the magnetic carrier itself in the developer acts as a soft developing electrode, the toner can be attached in proportion to the charge density of the electrostatic latent image, that is, suitable for reproduction of a gradation image. is there. Further, the developing device itself can be made compact.

  As this two-component developing type magnetic brush developing apparatus, a magnetic brush developing method using a developing sleeve which is a developer carrying member is generalized. In order to achieve the purpose of efficiently developing the electrostatic latent image on the photosensitive drum, a two-component containing a magnetic carrier such as a magnetic powder, for example, ferrite, and a toner in which a pigment is dispersed in a resin. The developer is a hollow cylindrical developer carrier made of a non-magnetic material having a magnetic pole inside the developer while the developer is agitated and mixed, and the toner retains electric charge by frictional charging due to mutual friction. Hold on the developing sleeve. By the developer sleeve, the developer is transported from the developer container to the developing region facing the photosensitive drum, and the developer is sprinkled by the action of the magnetic field in this developing region to rub the surface of the photosensitive drum, The electrostatic latent image formed on the photosensitive drum is developed.

  This two-component magnetic brush developing method using a developing sleeve is used in many products, mainly black and white digital copying machines and full-color copying machines that require high image quality.

  Until now, when the rotational speed of the photosensitive drum is relatively low, that is, in the case of a relatively low-speed copying machine, a short development time is sufficient and a good developed image can be obtained. Even one was good. However, when the rotational movement speed of the photosensitive drum is increased in the recent flow of demands for high speed copying machines, it is not always possible to form a suitable image with only one developing sleeve. .

  As a countermeasure, there is a method of increasing the developing efficiency by increasing the peripheral speed of the developing sleeve. However, if the peripheral speed of the developing sleeve is increased, the centrifugal force acting on the developer forming the magnetic brush increases, and the developing The scattering of the agent increases, causing the inside of the copying machine to be contaminated, and the function of the apparatus may be deteriorated.

  Therefore, as another countermeasure, two or more developer carriers such as a developing sleeve are used, and they are arranged adjacent to each other so as to be adjacent to each other, and are continuously transmitted along each other. Thus, a so-called multi-stage magnetic brush developing method has been proposed in which the developer is conveyed to extend the developing time and increase the developing ability.

  Here, FIG. 9 shows an example of a conventional multi-stage magnetic brush developing type developing device having two developing sleeves.

  The developing device 104 includes a developer container 122 disposed in parallel with the photosensitive drum 101, and the inside thereof is partitioned into a developing chamber R 1 and a stirring chamber R 2 by a partition wall 123 parallel to the photosensitive drum 101. A developer 120 in which toner particles and a magnetic carrier are mixed is accommodated in the developing chamber R1 and the agitating chamber R2.

  A conveying screw 124 is accommodated in the developing chamber R1, and the developer 120 is conveyed along a longitudinal direction parallel to the photosensitive drum 101 of the developer container 122 by rotational driving. The developer conveying direction by the screw 125 is opposite to that by the screw 124.

  The partition wall 123 has openings on the front side and the back side, and the developer 120 conveyed by the screw 124 is delivered to the screen 125 from one of the openings, and the developer 120 conveyed by the screw 125 is It is delivered to the screw 4 from the other one of the above openings.

  An opening is provided in a portion of the developer container 2 adjacent to the photosensitive drum 101, and two openings, a first developing sleeve 126 and a second developing sleeve 128 made of a nonmagnetic material are provided in the opening. A developer carrier is provided.

  Of the two developer carriers, the first developing sleeve 126 facing upstream in the rotational direction a of the photosensitive drum 101 rotates in the direction of arrow b (opposite to the rotational direction a of the photosensitive drum 101). Then, an appropriate developer layer thickness is provided by a blade-like developer regulating member (layer thickness regulating blade) 121 disposed upstream of the developing area A1 in the rotational direction of the developing sleeve 126, here at the upper end of the developer container 122 opening. Then, the developer 120 is carried and conveyed to the first development area A1.

  A roller-shaped first magnetic field generating means (mag roller) 127 is fixedly disposed in the developing sleeve 126. The first mag roller 127 has a developing magnetic pole S1 facing the first developing area A1. A developer magnetic brush is formed by the developing magnetic field formed by the developing magnetic pole S1 in the first developing area A1, and this magnetic brush contacts the photosensitive drum 101 that rotates in the direction of arrow a in the first developing area A1. The electrostatic latent image is developed in the first development area A1.

  The first mag roller 126 has N 1, N 2, N 3, and S 2 poles in addition to the developing magnetic pole S 1, and the N 2 pole and the N 3 pole are adjacent to each other with the same pole in the developer container 2. And a barrier is formed against the developer 120.

  Further, a second developer is carried in a region below the first developing sleeve 126 and on the downstream side of the photosensitive drum 101 in the rotational direction a, substantially opposed to both the first developing sleeve 126 and the photosensitive drum 101. A second developing sleeve 128, which is a body, is rotatably arranged in the direction of arrow c. The second developing sleeve 128 is made of a non-magnetic material like the first developing sleeve 126, and a roller-shaped second mag roller 129, which is a second magnetic field generating means, is installed in a non-rotating state inside the second developing sleeve 128. The second mag roller 129 has five poles S3, N4, S4, N5, and S5.

  The developer 120 flows through the first developing sleeve 126 in the order of N 2 → S 2 → N 1 → S 1 → N 3, and then the developer on the first developing sleeve 126 moves to the second developing sleeve 128. Then, the sheet is conveyed on the second developing sleeve 128 in the order of S3 → N4 → S4 → S5 → N5. Here, the delivery of the developer is performed between the opposite poles (N3 pole and S3 pole) that are substantially opposed to each other. This is because the magnetic field lines are not formed in the case of the same poles, so that stable delivery cannot be performed.

  Among these, the N4 pole is in contact with the photosensitive drum 101 in the opposite portion of the second developing sleeve 128 and the photosensitive drum 101, that is, in the second developing area A2, and after passing through the first developing area A2. The electrostatic latent image on the photosensitive drum 101 is further developed a second time. Thus, high development efficiency is achieved by performing the second development.

  As described above, by adopting a configuration in which two developing sleeves are provided, for example, even if the developing time is shortened as the peripheral speed of the photosensitive drum is increased, high developing efficiency is possible, and the developing density is reduced. Good image formation can be achieved without causing density unevenness.

  By the way, in the developing device provided with the two developing sleeves as described above, the magnetic flux density in the region where the first mag roller 127 and the second mag roller 129 face each other becomes high, and the developer is restrained by the magnetic force. Power is increasing. Therefore, the space on the developing container side between the two developing sleeves 126 and 128 tends to be filled with the developer due to the interaction between the magnetic force generated by the two mag rollers and the propulsive force accompanying the rotation of the developing sleeve. .

  The developer filling this space is stored in the stirring chamber R2 from the second developing sleeve 128 after the end of the previous development. That is, the developer is a developer whose toner concentration is different from that of the developer that has passed through the layer thickness regulating blade 121 in a normal process.

  The developer is transported to the second developing sleeve 128 again by the action of the rotation of the developing sleeve 128 and the magnetic force of the mag roller 129, and the developer coating amount of the second developing sleeve 128 is appropriate by the layer thickness regulating blade 121. The coating amount of the first developing sleeve 126 thus made becomes much larger.

  In a state where such a developer is mixed, not only does the formation of a defective image such as a decrease in density after durability occur in the developing process of the electrostatic latent image on the photosensitive drum 101, but also the coating amount of the second developing sleeve 128 By itself becoming much larger than the appropriate value, overflow from the ground capri and the developing container 122 is generated, and various problems such as scattering of toner into the apparatus are caused.

As a countermeasure against the problem that the developer is rotated between the two developing sleeves as described above, a regulating member that regulates the entry of the developer into the region between the first developing sleeve 126 and the second developing sleeve 128 Has been proposed (see Patent Document 1). As shown in FIG. 13, a restricting member 130 is provided in the region between the first developing sleeve 126 and the second 128 for preventing revolving so as to prevent the developer from entering the second developing sleeve 128.
JP 2004-191469 A

  However, when the restriction member 30 is provided, the following new problem may be caused.

  Originally, the regulating member only mechanically blocks the developer that tries to enter between the two developing sleeves by the action of the magnetic force of the two mag rollers and the propulsive force accompanying the rotation of the developing sleeve. Therefore, the regulating member receives the pressure by the developer in a very high state. As a result, the developer in the vicinity of the regulating member is hardened by the pressure and may cause a problem of aggregation.

  The developer agglomerates fall from the regulating member into the stirring chamber during the durability process, and eventually get caught by the layer thickness regulating blade of the first developing sleeve while being conveyed by the conveying screw, thereby inhibiting the developer coating. However, the image may be affected as a so-called white streak-like image.

  In view of the above problems, an object of the present invention is to provide a developing device that suppresses the occurrence of aggregation flaws while eliminating image defects due to the intrusion of the developer between the first developing sleeve and the second developing sleeve. It is what.

  The above object is achieved by the following developing device.

First and second developer carriers for developing an electrostatic latent image on the image carrier, and a plurality of magnetic poles enclosed and fixedly disposed in the first and second developer carriers, respectively. First and second magnetic field generating means, a developer container for rotatably supporting the first and second developer carriers, and an area inside the developing machine and extending adjacent to each other In a developing device comprising: a regulating member that regulates the intrusion of the developer into the region between the first and second developer carriers.
The developing device is characterized in that a weak regulation region having a weaker regulation force than that of another region is provided in a part of the longitudinal direction.

  The above object can also be achieved by the following developing device.

A developer carrier for developing an electrostatic latent image on the image carrier, a magnetic field generating means having a plurality of magnetic poles contained and fixed in the developer carrier, and the developer carrier can be rotated. In a developing device comprising: a developing container to be supported; and a regulating member that regulates the rotation of the developer on the developer carrying member in an area inside the developing machine.
The developing device is characterized in that a weak regulation region having a weaker regulation force than that of another region is provided in a part of the longitudinal direction.

  According to the present invention, it is possible to provide a developing device free from a defective image by preventing coagulation flaws from being generated by the restricting member while suppressing the rotation of the agent in the second developing sleeve.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
FIG. 1 shows an image forming apparatus to which the present invention can be applied. The image forming apparatus shown in the figure is a four-color full-color electrophotographic image forming apparatus having four image forming units, and the figure is a longitudinal sectional view schematically showing the schematic configuration thereof. Note that this embodiment is one form to which the present invention can be applied, and is not limited to this.

  In the image forming apparatus shown in the figure, four image forming portions (image forming stations) are arranged from the upstream side to the downstream side along the rotation direction (arrow R7 direction) of the intermediate transfer belt 7 as an intermediate transfer member. ing.

  Each image forming section includes drum-type electrophotographic photosensitive members (hereinafter referred to as “photosensitive drums”) 1a, 1b, 1c, and 1d as image carriers, and in this order, yellow, magenta, cyan, and black. This is a photosensitive drum for forming toner images of respective colors.

  The photosensitive drums 1a, 1b, 1c, and 1d are each driven to rotate in the direction of arrow R1 (clockwise in FIG. 1). Around each of the photosensitive drums 1a, 1b, 1c, and 1d, chargers (charging means) 2a, 2b, 2c, and 2d, exposure devices (latent image forming means) 3a, 3b, 3c, 3d, developing devices (developing means) 4a, 4b, 4c, 4d, primary transfer rollers (primary transfer means) 5a, 5b, 5c, 5d, drum cleaners (cleaning devices) 6a, 6b, 6c, 6d are arranged. Has been. An endless intermediate transfer belt 7 as an intermediate transfer member is stretched around the primary transfer rollers 5a, 5b, 5c, 5d and the secondary transfer counter roller 8 described above. The intermediate transfer belt 7 is pressed by the primary transfer rollers 5a, 5b, 5c, and 5d from the back side thereof, and the surface thereof is brought into contact with the photosensitive drums 1a, 1b, 1c, and 1d. The intermediate transfer belt 7 rotates in the direction of arrow R7 as the secondary transfer counter roller 8 also serving as a driving roller rotates in the direction of arrow R8. The rotation speed of the intermediate transfer belt 7 is set to be approximately the same as the rotation speed (process speed) of each of the photosensitive drums 1a, 1b, 1c, and 1d.

  A secondary transfer roller (secondary transfer means) 9 is disposed at a position corresponding to the secondary transfer counter roller 8 on the surface of the intermediate transfer belt 7. The secondary transfer roller 9 holds an intermediate transfer belt 7 between the secondary transfer counter roller 8 and a secondary transfer nip (secondary transfer) between the secondary transfer roller 9 and the intermediate transfer belt 7. A transfer portion) is formed.

  The transfer material P used for image formation is stored in a state of being stacked on the paper feed cassette 10. The transfer material P is supplied to the above-described secondary transfer nip portion by a feeding / conveying device (all not shown) having a paper feeding roller, a conveying roller, a registration roller, and the like. A fixing device 11 having a fixing roller 12 and a pressure roller 13 pressed against the fixing roller 12 is disposed on the downstream side of the secondary transfer nip portion along the conveyance direction of the transfer material P, and further fixing. A paper discharge tray is disposed on the downstream side of the apparatus 11.

  In the image forming apparatus configured as described above, a four-color full-color toner image is formed on the transfer material P as follows.

  First, the photosensitive drums 1a, 1b, 1c, and 1d are rotationally driven at a predetermined process speed in the direction of the arrow by a photosensitive drum driving motor (not shown), and are set to a predetermined polarity and potential by the chargers 2a, 2b, 2c, and 2d. Uniformly charged. The charged photosensitive drums 1a, 1b, 1c, and 1d are exposed based on image information by the exposure devices 3a to 3d, and the charge of the exposed portions is removed to form an electrostatic latent image for each color.

  These electrostatic latent images on the photosensitive drums 1a, 1b, 1c, and 1d are developed as toner images of respective colors of yellow, magenta, cyan, and black by the developing devices 4a, 4b, 4c, and 4d. These four color toner images are sequentially primary-transferred onto the intermediate transfer belt 7 by the primary transfer rollers 5a, 5b, 5c, and 5d in the primary transfer nip. Thus, the four color toner images are superimposed on the intermediate transfer belt 7. At the time of primary transfer, toner (residual toner) that is not transferred to the intermediate transfer belt 7 and remains on the photosensitive drums 1a, 1b, 1c, and 1c is removed by the drum cleaners 6a, 6b, 6c, and 6d. The photosensitive drums 1a, 1b, 1c, and 1d from which the residual toner has been removed are used for the next image formation.

  The four color toner images superimposed on the intermediate transfer belt 7 as described above are secondarily transferred to the transfer material P. The transfer material P conveyed from the paper feed cassette 10 by the feeding / conveying device is supplied to the secondary transfer nip T <b> 2 by the registration roller so as to be synchronized with the toner image on the intermediate transfer belt 7. To the supplied transfer material P, the four-color toner images on the intermediate transfer belt 7 are secondarily transferred collectively at the secondary transfer nip by the secondary transfer roller 9.

  The transfer material P onto which the four color toner images have been secondarily transferred is conveyed to the fixing device 13 where it is heated and pressed to fix the toner image on the surface. The transfer material P after the toner image is fixed is discharged onto a paper discharge tray. The four-color full-color image formation on one surface (front surface) of one transfer material P is thus completed.

  Here, the developing device of this embodiment will be described in detail with reference to FIG. Since each developing device used in the image forming apparatus main body of the present embodiment has the same configuration, only one developing device will be described. In the following description, the developing device 4 may refer to any of the developing devices 4a, 4b, 4c, and 4d.

  The developing device 4 includes a developer container 20, and the inside thereof is divided into a developing chamber R 1 and a stirring chamber R 2 by a partition wall 23. On the other hand, the developer 33 in which the toner particles and the magnetic carrier are mixed is accommodated in the developing chamber R1 and the stirring chamber R2. The magnetic carrier used in the present invention may be a ferrite carrier, a resin magnetic carrier made of a binder resin, a magnetic metal oxide, or a nonmagnetic metal oxide.

  A conveying screw 24 is accommodated in the developing chamber R1 and conveys the developer along the longitudinal direction of the developing sleeves 26 and 28 by rotational driving. The developer conveying direction by the screw 25 accommodated in the stirring chamber R <b> 2 is opposite to that by the screw 24.

  The partition wall 23 is provided with openings on the front side and the back side, and the developer conveyed by the screw 24 is delivered to the screen 25 from one of the openings, and the developer conveyed by the screw 25 is It is delivered to the screw 24 from the other one of the openings.

  An opening is provided in a portion of the developer container 20 adjacent to the photosensitive drum 1, and the opening is made of a material such as aluminum or nonmagnetic stainless steel, and has a surface with appropriate irregularities. Two developing sleeves of a carrier 26 and a second developer carrier 28 are provided.

  The upstream developer sleeve 26, which is the first developer carrier, rotates in the direction of arrow b (the direction opposite to the photosensitive member rotation direction), and an appropriate developer layer is formed by the layer thickness regulating blade 21 at the upper end of the developer container opening. After the thickness is regulated, the developer is carried and conveyed to the first development area A1. A roller-shaped first mag roller 27 is fixedly disposed in the upstream developing sleeve 26. The first mag roller 27 has a developing magnetic pole S1 facing the first developing area A1. The developing magnetic pole S1 forms a developer magnetic brush by the developing magnetic field formed in the first developing area A1, and the magnetic brush contacts the photosensitive drum 1 rotating in the direction of arrow a in the first developing area A1. The electrostatic latent image is developed in the first development area A1. At this time, the toner adhering to the magnetic brush and the toner adhering to the surface of the developing sleeve are also transferred to the image area of the electrostatic latent image and developed. In this embodiment, the first mag roller 27 has N1, N2, N3, and S2 poles in addition to the developing magnetic pole S1, and the N1 pole and the N3 pole are adjacent to each other and have a repulsive magnetic field. Thus, a barrier is formed against the developer.

  The downstream developing sleeve 28 as the second developer carrying means is placed in the direction substantially in the direction of the arrow C (in the same direction as the upstream developing sleeve) in a region substantially facing both the upstream developing sleeve 26 and the photosensitive drum 1 below the upstream developing sleeve 26. ) Is rotatably arranged. The downstream developing sleeve 28 is made of a nonmagnetic material like the upstream developing sleeve 26, and a roller-like second mag roller 29 as a magnetic field generating means is installed in a non-rotating state in the second developing sleeve 28. The mag roller 29 has five poles S3, N4, S4, N5, and S5. Among these, the magnetic brush on the N4 pole is in contact with the photosensitive drum 1 in the second development area A2, and the development is further performed on the photosensitive body after passing through the first development area A1. The S3 pole and the S5 pole are the same pole, and a repulsive magnetic field is formed between the S3 pole and the S4 pole, and a barrier is formed against the developer. Of these, the S3 pole faces the N3 pole of the first mag roller 27 contained in the upstream developing sleeve 26 in the vicinity of the position where both sleeves are closest. Hereinafter, the flow of the developer will be described with reference to an enlarged view (FIG. 3) near the first developing sleeve 26 and the second developing sleeve 28. A repulsive magnetic field is formed between the N3 pole and the N2 pole of the first developing sleeve 26, and a repulsive magnetic field is also formed between the S3 pole and the S5 pole of the second developing sleeve 28, so that the first The developer that has been transported on the developing sleeve 26 and passed through the developing region reaches the N3 pole and cannot pass through the closest position of both sleeves due to the repulsive magnetic field, and from the N3 pole to the S3 pole direction as indicated by the arrow d. It moves to the downstream developing sleeve 28 side according to the magnetic field lines extending to the downstream developing sleeve 28 and is conveyed to the conveying screw 5 in the stirring chamber. By providing the downstream developing sleeve 28 below the upstream developing sleeve 26 as in the present embodiment, the developer flows through the upstream developing sleeve 26 in the order of N2-> S2-> N1-> S1-> N3, and then the upstream developing sleeve. The developer on 26 is blocked by the repulsive magnetic field of both sleeves, moves to the downstream developing sleeve 28, is transported on the downstream developing sleeve 28 in the order of S3-> N4-> S4-> N5-> S5, and is blocked by the repulsive magnetic field at the S5 pole. Then, the developer is peeled off to the stirring chamber R2.

  The delivery poles N3 and S3 do not need to completely face each other. The developer can be delivered smoothly as long as it is substantially opposed within the range of 45 ° from the completely opposed state.

  Here, a region between the first developing sleeve 26 and the second developing sleeve 28 in the developing container 20 related to the present invention will be described.

  In the developing device of this embodiment, a regulating member 30 is disposed in a region between the first developing sleeve 26 and the second developing sleeve 28. In this embodiment, the regulating member 30 has a partition wall 23 between the developing chamber R1 and the stirring chamber R2 so as to face both the first developing sleeve 26 and the second developing sleeve 28 with a gap. It is arranged to extend continuously from.

  The flow of the developer when the regulating member 30 is used will be described with reference to FIG. 3. As described above, the developer moves from the first developing sleeve 26 to the second developing sleeve 28, and the first developing is performed. The developer conveyed on the sleeve 28 in the order of S3 → N4 → S4 → N5 → S5, and peeled off to the stirring chamber R2 at the S5 pole, is driven by the propulsive force accompanying the rotation of the second developing sleeve 28 and the first. The developing sleeve 26 and the second developing sleeve 28 tend to move to the region between the first developing sleeve 26 and the second developing sleeve 28 by the magnetic force of the magnetic poles N3 and S3 of the developer delivery portion. When the developer moves to this region, the developer tends to enter between the two developing sleeves 26, 28, the amount of developer coating on the second developing sleeve 28 increases, and various image defects are a concern. As described in the section of the prior art.

  Actually, as described above, in the developing device according to the present embodiment, the regulating member 30 is disposed in the region between the first developing sleeve 26 and the second developing sleeve 28. The regulating member 30 blocks the developer that is about to enter the region, and prevents the developer from entering between the two developing sleeves 26 and 28.

  While the presence of the regulating member 30 can prevent the developer from entering the region between the two developing sleeves 26 and 28, the presence of the regulating member 30 causes the developer to stay in the vicinity of the regulating member 30. In addition, a large pressure is applied to the retained developer. As a result, the developer aggregates into a lump and may cause a new image defect. It is an object of the present invention to solve this problem.

  The present invention avoids the above problem by adopting the following configuration.

  The cause of the occurrence of the coagulation flaw is that the developer regulated by the regulating member 30 has no escape place and tries to stay there, whereas the developer is supplied later after the development sleeve rotates. Therefore, the developer is compressed in the region where the regulating member 30 is disposed, and a large pressure is applied. The developer that has been subjected to a large pressure becomes agglomerated wrinkles and may cause image defects.

  Therefore, the present invention is characterized in that a region where the developer collected near the regulating member 30 can escape is provided so that the developer does not stay near the regulating member 30.

  A specific configuration will be described with reference to FIG. FIG. 4 is a perspective view of the developing device of this embodiment as viewed obliquely from above. In order to describe the regulating member 30, the first developing sleeve 26 and the second developing sleeve 28 are indicated by dotted lines.

  A feature of the developing device according to the embodiment is that the regulating member 30 is not provided in the entire thrust area, and there is a region where the regulating member 30 is not present in a part of the thrust direction. Since the developer does not stay in the region where the regulating member 30 is not present, the developer regulated by the regulating member 30 in other regions also escapes to the region where the regulating member 30 is not present, so that the developer is removed. It becomes difficult to stay. As a result, the occurrence of agglomerated wrinkles is suppressed, and image defects due to the agglomerated wrinkles do not occur.

  In the present embodiment, the regulating member 30 is arranged in the central portion in the thrust direction, and regions without the regulating member are provided in the regions at both ends. This is due to the following reason.

  By providing a region without the regulating member 30 in a part in the thrust direction, it is possible to suppress the occurrence of agglomerated soot as described above. However, in the region where the regulating member 30 is not present, the developer enters between the two developing sleeves 26 and 28, and the coating amount of the second developing sleeve 28 increases, which may cause image defects. For this reason, it is inherently not desirable to set an area without a regulating member as an image area. However, the width of the developer coat area and the image guarantee area is not actually equal, and the developer coat area is set to be wider than the image guarantee area in most cases. This is because of the nature of the image guarantee area, and there is a reason that the coat area needs to be large enough to withstand fluctuations due to some errors during assembly and parts accuracy. This is because an area outside the standard size outside the area may be provided with an area for printing information such as a reference mark (such as a registration mark) for position confirmation or numbering.

  Outside such an image guarantee area, a fine image is rarely required, and if an image appears for the time being, the function is sufficiently satisfied. For this reason, some image defects are often allowed.

  Therefore, in this embodiment, a portion where the regulating member 30 is not provided is provided in an area outside the image guarantee area provided at both ends in the thrust direction. Therefore, even if the developer is not well regulated and the coating amount of the second developing sleeve is somewhat increased, the final image is not greatly affected because it is outside the image guarantee area.

  The place where the developer accumulated in the vicinity of the regulating member 30 is allowed to escape is a region where the mag roller in the developing sleeve exists. This is because if the developer escapes to a place where the mag roller does not exist, the developer that escapes cannot be held well by the mag roller, and the developer may overflow to the outside of the apparatus. Therefore, it is necessary to provide a region without the regulating member in the region where the mag roller exists. Therefore, it is necessary to make the regulating member shorter than the thrust length of the mag roller in the developing sleeve. At this time, it is preferable that the length is shorter than both of the first mag roller and the second mag roller, and it is preferable that the mag roller is disposed inside both ends of the mag roller. By adopting this configuration, the developer that has escaped from the vicinity of the regulating member does not overflow.

  When the thrust positional relationship so far is summarized using FIG. 5, the overflow of the developer can be suppressed by making the thrust length of the regulating member 30 shorter than the thrust width of the tuna roller in the developing sleeves 26 and 28. . Further, if the thrust length of the regulating member 30 is made longer than the image guarantee area, even if the developer is not well regulated in a portion where there is no regulating member, the final image is not greatly affected.

(Example 2)
This embodiment has almost the same configuration as that of the first embodiment. In the following, differences from the first embodiment will be mainly described with reference to FIG.

  In Example 1, regions where the regulating member 30 is not provided are provided at both ends in the thrust direction as regions where the developer escapes. The configuration without the regulating member 30 is the best configuration for allowing the developer near the regulating member 30 to escape, but there is a concern that the coating amount of the developer on the second developing sleeve 28 increases at that portion. Exists.

  As described in the section of the first embodiment, even if the coating amount of the developer on the second developing sleeve 28 is increased, there is not much problem as long as it is outside the image guarantee area at both ends. However, if the coating amount becomes too large, there may be a problem in the image regardless of the end portion. In this case, it is desirable that the developer escapes to some extent while restricting the invasion of the developer to some extent. Such a configuration can be dealt with by changing the gap between the second developing sleeve 28 and the regulating member 30 well.

  According to the study by the inventors, the narrower the gap between the second developing sleeve 28 and the restricting member 30, the stronger the restriction of the restriction member, and the wider, the weaker the restriction of the restriction member, so that the developer enters. I found it easier. Thus, it has been found that by managing the gap, it is possible to realize a configuration in which the developer escapes to some extent while restricting the intrusion of the developer to some extent as described above.

  Therefore, in this embodiment, instead of providing a region where there is no restriction member as in the first embodiment, a portion where the gap between the second developing sleeve 28 and the restriction member 30 is wider than other regions is provided. The configuration.

  In the present embodiment, specifically, the gap between the second developing sleeve 28 and the regulating member 30 is set to 1.0 mm at the centrally restricted portion and 5.0 mm at the weakly regulated portions at both ends. I made it. By adopting such a configuration, it is possible to prevent the developer from entering the second developing sleeve 28 at the central portion, and to let the developer escape within a range that does not affect the image at both end portions. Can be suppressed.

(Example 3)
This embodiment has substantially the same configuration as the above-described first and second embodiments. Hereinafter, differences from the first and second embodiments will be mainly described with reference to FIG.

  Up to now, in the parts where both the first and second embodiments are more restrictive, the distance between the restricting member 30 and the second developing sleeve 28 is basically constant. However, if this distance is constant, the restriction is restricted. There is a concern that the developer regulated by the member 30 is somewhat difficult to move in the thrust direction.

  This embodiment has the following configuration in view of the above concerns.

  The feature of this embodiment is that the distance between the regulating member 30 and the second developing sleeve 28 gradually increases from the center toward both ends. Specifically, the gap between the second developing sleeve 28 and the regulating member 30 is 1.0 mm at the center and 5.0 mm at both ends, so that the slope gradually increases. With such a configuration, the developer regulated by the regulating member 30 gradually moves from the central portion toward both ends according to the inclination of the regulating member 30. For this reason, there is a merit that the effect of releasing the developer from the back of the regulating member is enhanced as compared with the case where no inclination is provided.

Example 4
In the embodiments so far, the case where there are two developing sleeves as the developing device 4 has been described. However, the present invention can be applied not only when there are two developing sleeves but also when there is only one developing sleeve.

  FIG. 8 is a sectional view of a developing device provided with one developing sleeve to which the present invention can be applied. Compared with the developing device described in the first embodiment, the configuration is substantially the same except that the number of developing sleeves is reduced by one, so detailed description will be omitted.

  Also in the developing device 4 having one developing sleeve, the regulating member 30 is disposed so as to face the developing sleeve with a gap. In the developing device having the two developing sleeves, the regulating member 30 regulates the intrusion of the developer between the two developing sleeves. In the developing device provided with the sleeve, the developer which has completed the development on the developing sleeve 26 is arranged so as to be swung around the developing sleeve 26 as it is to be coated on the developing sleeve again. Yes.

  When the developer after the development is accompanied, there is a concern that the developability is reduced only in that portion, so that it is necessary to arrange such a regulating member 30, but on the other hand, there is a problem of occurrence of coagulation flaws. What can be obtained is the same as a developing device having two developing sleeves.

  As a countermeasure against the coagulation flaw, a weakly regulated region may be provided in a part of the longitudinal direction as in the case of the developing device including two developing sleeves.

  At that time, in the configuration provided with two developing sleeves so far, the gap between the second developing sleeve and the regulating member 30 was important. Needless to say, in the developing device provided with one developing sleeve, The gap between the developing sleeve 26 and the regulating member 30 that is present only one is important.

  Although not described in detail, if the above-described points are noted, all of the configurations described for the regulating member 30 in Examples 1 to 3 can be applied to the developing device including one developing sleeve of the present example. Is possible.

It is sectional drawing of the image forming apparatus of a present Example. It is sectional drawing of the image development apparatus of a present Example. FIG. 6 is a cross-sectional view of the vicinity of a developing sleeve. It is a perspective view of a developing device. It is a figure showing the dimension of the longitudinal direction. It is a perspective view of a developing device. It is a perspective view of a developing device. It is sectional drawing of a developing device. It is sectional drawing of the conventional image development apparatus.

Explanation of symbols

1 Photosensitive drum (image carrier)
4 Developing device 26, 28 Developing sleeve 27, 29 Magnet roller 30 Regulating member

Claims (10)

First and second developer carriers for developing an electrostatic latent image on the image carrier, and a plurality of magnetic poles enclosed and fixedly disposed in the first and second developer carriers, respectively. The first and second magnetic field generating means, the developing container that rotatably supports the first and second developer carriers, and the region inside the developing container and extending adjacent to each other In a developing device comprising a regulating member that regulates the intrusion of the developer into the region between the first and second developer carriers,
A developing device characterized in that a weak regulation region having a weaker regulation force than that of another region is provided in a part of the longitudinal direction. A developer carrier for developing an electrostatic latent image on the image carrier, a magnetic field generating means having a plurality of magnetic poles contained and fixed in the developer carrier, and the developer carrier can be rotated. In a developing device comprising: a developing container to be supported; and a regulating member that regulates the rotation of the developer on the developer carrying member in an area inside the developing machine.
A developing device characterized in that a weak regulation region having a weaker regulation force than that of another region is provided in a part of the longitudinal direction.   3. The developing device according to claim 1, wherein a gap between the regulating member and the developer carrying member is wider in the weakly regulated region than in other regions.   4. The developing device according to claim 1, wherein the restricting member is not provided in the weakly restricted region.   The developing device according to claim 1, wherein a gap between the regulating member and the developer carrying member is gradually expanded toward a weak regulating region.   The developing device according to claim 1, wherein the weakly regulated regions are provided at both ends in the longitudinal direction.   7. The developing according to claim 1, wherein the regulating member has a shorter length in the longitudinal direction than the magnetic field generating means, and is disposed on the inner side of both end positions of the magnetic field generating means. apparatus.   The developing device according to claim 1, wherein in the weakly regulated region, additional information outside the standard size is developed.   The developing device according to claim 8, wherein the additional information includes any one of a position confirmation mark, numbering information, and job information.   The developing device according to claim 1, wherein the weakly regulated region is provided outside the image region.

Images