JP2005202242A - Developing device, processing cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which is equipped with a conveying member for conveying developer containing toner and magnetic carrier in the direction of a rotary shaft by its rotation, and a magnetic field generating means for stirring supplied toner to satisfactorily circulate the developer even at the root of developer nap formed by the magnetic field generating means, to provide a processing cartridge provided with the developing device, and to provide an image forming apparatus provided with the developing device or the processing cartridge. <P>SOLUTION: The developing device has: the conveying member 54Y that conveys developer containing toner and magnetic carrier in the direction of the rotary shaft by its rotation; the magnetic field generating means 90Y which is disposed near the conveying member 54Y and generates a magnetic field; and a scraping member 93Y that scrapes a mass of developer formed by the electric field generating means 90Y. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a developing device including a conveying member that conveys a developer containing toner and a magnetic carrier in a rotation axis direction by rotation, a process cartridge including the developing device, and a copy including the developing device or the process cartridge. The present invention relates to an image forming apparatus such as a printer, a facsimile machine, or a printer.

  2. Description of the Related Art In image forming apparatuses such as copying machines, facsimile machines, and printers, developing apparatuses that develop an image carrier such as a photoconductor using a developer containing toner and a magnetic carrier are known. In such a developing device, toner is consumed by development, so that the toner is replenished in a timely manner. However, stirring and mixing of the replenished toner and the developer is insufficient, and the replenished toner is supplied. In the case where all of the toner cannot be brought into contact with the magnetic carrier, the toner continues to be conveyed while being rubbed with each other, and the charged charge is near 0 and the toner is insufficiently charged. Charged toner is generated, and sufficient chargeability with the desired polarity cannot be secured. Problems such as development unevenness such as white background fog on the formed image, problems such as contamination inside the machine due to toner scattering, image contamination, etc. May occur. Therefore, such a developing device is generally provided with a member for stirring and mixing the supplied toner and the developer to uniformly disperse the supplied toner.

  As such a developing device, for example, as described in [Patent Document 1] and [Patent Document 2], a developing member that transports a developer containing toner and a magnetic carrier in the direction of the rotation axis by rotation is provided. Developing devices. The conveying members described in [Patent Document 1] and [Patent Document 2] have a first conveying member and a second conveying member which are arranged in parallel to each other. The first conveying member and the second conveying member have a screw shape, and are rotated so as to convey the developer in opposite directions, and are conveyed so as to circulate the developer. However, it is designed to stir.

  However, only by stirring the developer with the first transport member and the second transport member, the replenished toner is transported in a state of floating on the developer originally circulated in the developing device, In some cases, the replenished toner is not sufficiently stirred, and thus the replenished toner is not uniformly dispersed in the developer, causing problems such as uneven development. In order to sufficiently stir, it may be possible to provide a stirrer with a shape for stirring separately from the screw shape on the transport member. However, this reduces the transport speed of the developer and causes uneven distribution of the developer. There is a problem of causing problems such as.

  Therefore, in the developing device described in [Patent Document 1], in addition to the conveying member, the developing device includes a magnetic field generating unit that acts on the magnetic carrier conveyed by the second conveying member. By forming developer spikes and supplying and transporting toner pressed against the spikes, the supplied toner is agitated and mixed to be uniformly dispersed in the developer.

JP 2000-89550 A Registered Utility Model No. 2506225

  However, in the developing device described in [Patent Document 1], since the magnetic field generating means is located below or on the side of the second conveying member, it is between the toner supply position and the position where the magnetic field generating means is disposed. Depending on the distance, it may be necessary to use a magnetic field generating means with a strong magnetic force in order to perform agitation well, but using a magnetic field generating means with a strong magnetic force increases the rotational torque of the second transport member. There is.

Therefore, the applicant has previously proposed a technique in which the magnetic field generating means is disposed above the second conveying member in order to prevent an increase in the rotational torque of the second conveying member.
However, when the magnetic field generating means is used, it is considered that the developer is hardly replaced at the root of the developer head formed by the magnetic field generating means, and the circulation is not sufficient regardless of the arrangement position.

  The present invention relates to a developing device provided with a conveying member that conveys a developer containing toner and a magnetic carrier in the direction of the rotation axis by rotation, and in particular, a development provided with a magnetic field generating means for stirring the supplied toner. A developing device that improves the circulation of the developer even at the root portion of the developer formed by the magnetic field generating means, a process cartridge including the developing device, and the developing device or the process cartridge. The object is to provide image forming apparatuses such as copiers, facsimiles, and printers.

  In order to achieve the above object, a first aspect of the present invention provides a conveying member that conveys a developer containing toner and a magnetic carrier in the direction of the rotation axis by rotation, and generates a magnetic field disposed in the vicinity of the conveying member. And a scraping member that scrapes off a lump of developer formed by the magnetic field generating means.

  According to a second aspect of the present invention, in the developing device according to the first aspect, the conveying member is provided with a first conveying member disposed to face the developing member disposed to face the image carrier, And a second conveying member disposed to face the first conveying member.

  According to a third aspect of the present invention, in the developing device according to the second aspect, a supply port for supplying toner into the developing device main body is disposed at a position where the toner is supplied to the second conveying member. And

  According to a fourth aspect of the present invention, in the developing device according to the third aspect, the magnetic field generating unit is configured to cause the toner to be supplied from the supply port to the second conveying member in the developer conveying direction by the second conveying member. A position downstream of the supply position and corresponding to a position in the vicinity of the downstream side of the supply position of the toner from the supply port to the second transport member in the rotation direction of the second transport member. It is characterized by that.

  According to a fifth aspect of the present invention, in the developing device according to any one of the second to fourth aspects, the scraping member is integral with the second conveying member.

  According to a sixth aspect of the present invention, in the developing device according to the fifth aspect, when the scraping member is exposed to the scraping member by the rotation of the second conveying member. When there is a partition between the magnetic field generation means and the scraping member, the developer lump is scraped off by contacting or approaching the partition. And

  According to a seventh aspect of the present invention, in the developing device according to any one of the fifth and sixth aspects, when the magnetic field generating means is exposed to the scraping member, the magnetic field generating means is When the tip of the scraping member has a portion along the locus drawn by the rotation of the second conveying member, and there is a partition between the magnetic field generating means and the scraping member, the partition is The tip of the scraping member has a portion forming a shape along a locus drawn by the rotation of the second conveying member.

  According to an eighth aspect of the present invention, in the developing device according to any one of the second to seventh aspects, the second conveying member is located on the upstream side in the developer conveying direction with respect to the arrangement position of the scraping member. Further, the downstream side is characterized in that the developer conveying speed is increased.

  According to a ninth aspect of the present invention, in the developing device according to any one of the first to eighth aspects, the magnetic field generating means is disposed above the conveying member.

  According to a tenth aspect of the present invention, there is provided a developing device according to any one of the first to ninth aspects, an image carrier, a charging unit for charging the image carrier, and a cleaning unit for cleaning the image carrier. And a process cartridge that is integrally provided with at least one of them and is detachable from the main body of the image forming apparatus.

  An eleventh aspect of the present invention is an image forming apparatus including the developing device according to any one of the first to ninth aspects or the process cartridge according to the tenth aspect.

  The present invention provides a conveying member that conveys a developer containing toner and a magnetic carrier in the direction of the rotation axis by rotation, a magnetic field generating unit that is disposed near the conveying member and generates a magnetic field, and the magnetic field generating unit. Since the developer is provided with a scraping member that scrapes off the formed developer lump, the developer lump formed by the magnetic field generating means stirs, mixes, and disperses the toner, and the scraping member. By scraping off the developer lump, the developer circulation in the root portion of the developer lump can be promoted and the stirring, mixing, and dispersion of the toner can be further improved. It can be sufficiently charged with polarity to prevent problems such as development unevenness such as white background fogging on the formed image, contamination in the machine due to toner scattering, and image contamination. Can, it is possible to provide a high developing device of the user of reliability which can perform good development.

  A first conveying member disposed opposite to the developing member disposed opposite to the image carrier, and a second conveying member disposed opposite to the first conveying member. The developer lump formed by the magnetic field generation means while preventing the developer from being biased by transporting the developer in a circulating manner by the first transport member and the second transport member. Thus, the toner is agitated, mixed, and dispersed, and the developer lump is scraped off by the scraping member, thereby further promoting the circulation of the developer at the root portion of the developer lump and stirring the toner. Further, since mixing and dispersion can be further improved, the toner can be sufficiently charged with a desired polarity. Problems such as development unevenness such as white background fog on the formed image, contamination in the machine due to scattering of the toner, Defects such as image dirt Can be prevented, it is possible to provide a high developing device reliability users can perform better development.

  If the supply port for supplying the toner into the developing device main body is disposed at a position where the toner is supplied to the second conveying member, the toner supplied from the supply port is immediately supplied to the developing member. The developer lump formed by the magnetic field generating means while preventing the developer from being biased by conveying the developer in a circulating manner by the first conveying member and the second conveying member, The toner is agitated, mixed, and dispersed, and the developer lump is scraped off by the scraping member to further promote the circulation of the developer at the root portion of the developer lump. Since the dispersion can be further improved, the toner can be sufficiently charged with a desired polarity. Problems such as development unevenness such as white background fog on the formed image and contamination in the machine due to scattering of the toner can be obtained. It is possible to prevent problems image dirt, it is possible to provide a higher developing device of the user of reliability which can perform good development.

  The magnetic field generating means is positioned downstream of the supply position of the toner from the supply port to the second transport member in the developer transport direction by the second transport member, and the second transport member rotates. If it is arranged corresponding to the position in the vicinity of the downstream side of the supply position of the toner from the supply port to the second conveying member in the direction, the magnetic field generating means is reduced in size and the increase in size of the apparatus is suppressed. However, the developer is circulated by the first conveying member and the second conveying member so as to circulate the developer, and the developer mass is well formed by the magnetic field generating means while preventing the developer from being biased. The developer lump further improves the stirring, mixing, and dispersion of the toner, and the developer lump is scraped off by the scraping member to further circulate the developer at the root of the developer lump. Promotes toner agitation Since mixing and dispersion can be further improved, the toner can be sufficiently charged with a desired polarity. Problems such as development unevenness such as white background fog on the formed image, contamination in the machine due to scattering of the toner, image It is possible to provide a developing device that can prevent defects such as dirt and the like and can perform better development with high user reliability.

  If the scraping member is integrated with the second transport member, the developer is supplied by the first transport member and the second transport member while suppressing an increase in cost due to the provision of the scraping member. The developer lump formed by the magnetic field generating means while being transported in a circulating manner to prevent bias of the developer is used to stir, mix, and disperse the toner, and the developer lump is removed by the scraping member. By scraping, it is possible to further promote the circulation of the developer at the root portion of the developer lump and to further improve the stirring, mixing, and dispersion of the toner, so that the toner is sufficiently charged with a desired polarity. It is possible to prevent problems such as uneven development such as white background fog on the formed image, contamination in the machine due to toner scattering, and problems such as image stains, and to perform better development It is possible to provide a high developing device reliability users.

  When the scraping member is exposed to the scraping member due to the rotation of the second conveying member, the scraping member is in contact with or close to the magnetic field generating means, and the scraping member and the scraping member When there is a partition wall between the members, the developer is circulated by the first transport member and the second transport member if the developer lump is scraped off by contacting or approaching the partition wall. The developer lump formed by the magnetic field generating means is stirred and mixed and dispersed while preventing the developer from being biased, and the developer lump is scraped off by the scraping member. This scraping is carried out from a portion closer to the root of the developer lump, thereby further promoting the circulation of the developer at the root of the lump of developer and further improving the stirring, mixing and dispersion of the toner. To do Therefore, it is possible to sufficiently charge the toner with a desired polarity, and it is possible to prevent problems such as development unevenness such as white background fog on the formed image, and problems such as in-machine contamination due to toner scattering and image contamination. Therefore, it is possible to provide a developing device with high user reliability that can perform better development.

  When the magnetic field generating means is exposed to the scraping member, the magnetic field generating means has a portion that forms a shape along the locus drawn by the rotation of the second conveying member by the tip of the scraping member, When there is a partition wall between the magnetic field generating means and the scraping member, the partition wall has a portion that has a shape along the locus drawn by the rotation of the second conveying member by the tip of the scraping member; In this case, the developer is circulated by the first conveying member and the second conveying member, and the developer is circulated to prevent the developer from being biased. The developer lump is scraped off by the scraping member, and the scraping member interferes with the root portion of the developer lump at the time of scraping. Row against This makes it possible to further promote the circulation of the developer at the root portion of the developer lump and to further improve the stirring, mixing, and dispersion of the toner. It is possible to prevent problems such as development unevenness such as white background fog on the formed image, in-machine contamination due to toner scattering, image contamination, etc., and better development can be performed. A developing device with high user reliability can be provided.

  Assuming that the second transport member has a shape in which the developer transport speed is higher on the downstream side than the upstream side in the developer transport direction with respect to the arrangement position of the scraping member. By rapidly transporting the developer at a portion where the developer transport speed of the transport member 2 is large, the developer is prevented from staying at the position where the scraping member is disposed, and the first transport member and the second transport member are prevented. The developer agglomerates formed by the magnetic field generating means while the developer is conveyed in such a way as to circulate well with the conveying member to prevent the deviation of the developer, and the toner is agitated, mixed, dispersed, and scraped. Since the developer lump is scraped off by the removing member, the developer can be further circulated in the root portion of the developer lump so that the stirring, mixing, and dispersion of the toner can be further improved. Desired It can be charged sufficiently with polarity, and it can prevent problems such as development unevenness such as white background fog on the formed image, contamination in the machine due to toner scattering, and problems such as image smearing, and better development It is possible to provide a developing device with high user reliability.

  If the magnetic field generating means is arranged above the conveying member, the arrangement position of the magnetic field generating means can be made relatively close to the arrangement position of the conveying member. A developer lump that can sufficiently stir, mix, and disperse the toner can be formed by the magnetic field generating means without using a strong magnetic field generating means that needs to be enlarged, and the scraping member By scraping off the developer lump, the developer circulation in the root portion of the developer lump can be promoted and the stirring, mixing, and dispersion of the toner can be further improved. It can be charged sufficiently with polarity, and can prevent problems such as development unevenness such as white background fog on the formed image, contamination in the machine due to scattering of toner, image contamination, etc. It is possible to provide a high developing device of the user of reliability which can perform good development.

  The present invention provides at least one of the developing device according to any one of claims 1 to 9, an image carrier, a charging unit for charging the image carrier, and a cleaning unit for cleaning the image carrier. Since the process cartridge is provided integrally with the image forming apparatus main body and is detachable from the main body of the image forming apparatus, it has a developing device having the above-described effects, and the toner is formed by the developer lump formed by the magnetic field generating means. The developer is stirred, mixed, and dispersed, and the developer lump is scraped off by the scraping member to promote the circulation of the developer at the root of the developer lump, and the toner is stirred, mixed, and dispersed. Since the toner can be sufficiently charged with a desired polarity, problems such as development unevenness such as white background fog on the formed image and toner scattering can be obtained. It is possible to provide a process cartridge with high user reliability that can prevent problems such as internal contamination and image contamination, can perform good development, and contribute to good image formation. .

  Since the present invention resides in an image forming apparatus including the developing device according to any one of claims 1 to 9 or the process cartridge according to claim 10, the developing device that exhibits the above-described effects or the above-described effects. The developer has a process cartridge, and the developer lump formed by the magnetic field generating means stirs, mixes, and disperses the toner, and the developer lump is scraped off by the scraping member. The circulation of the developer at the root portion of the lump of the toner can be promoted, and the stirring, mixing and dispersion of the toner can be further improved, so that the toner can be sufficiently charged with a desired polarity, and the white background on the formed image can be obtained. It is possible to prevent problems such as development unevenness such as fogging, in-machine contamination due to toner scattering, image contamination, etc., and good development can be performed. It is possible to provide an image forming apparatus with high reliability of the user which can performs the image formation.

  FIG. 1 schematically shows an image forming apparatus to which the present invention is applied and which can form a color image. The image forming apparatus 100 is a color laser printer, but may be other types of image forming apparatuses such as other types of printers, facsimile machines, copiers, and multifunction machines of copiers and printers. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside. This is the same when the image forming apparatus 100 is used as a facsimile. The image forming apparatus 100 can form an image using plain paper generally used for copying, OHP sheets, thick paper such as cards and postcards, and envelopes as sheet-like recording media. .

  The image forming apparatus 100 includes a plurality of photosensitive drums 20Y, 20C, 20M, and 20BK that can form images as images corresponding to colors separated into yellow, magenta, cyan, and black, respectively. Adopted tandem structure. The photoconductive drums 20Y, 20C, 20M, and 20BK are arranged on the outer peripheral surface side, that is, the image forming surface side of the transfer belt 11 as an intermediate transfer member, which is an endless belt disposed almost at the center inside the main body of the image forming apparatus 100. positioned.

  The transfer belt 11 is movable in the direction of the arrow A1 while facing the photosensitive drums 20Y, 20C, 20M, and 20BK. The visible image, that is, the toner image formed on each of the photosensitive drums 20Y, 20C, 20M, and 20BK is superimposed and transferred onto the transfer belt 11 that moves in the direction of the arrow A1, and then the transfer paper that is a transfer material as a recording medium. The images are transferred to S in a batch.

  In the superimposing transfer to the transfer belt 11, the toner images formed on the photosensitive drums 20Y, 20C, 20M, and 20BK are transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. As described above, voltage application by primary transfer rollers 12Y, 12C, 12M, and 12BK disposed at positions facing the respective photosensitive drums 20Y, 20C, 20M, and 20BK across the transfer belt 11 causes the A1 direction upstream. The timing is shifted toward the downstream side.

  The transfer belt 11 is an elastic belt whose entire layer is formed using an elastic member such as a rubber agent. The transfer belt 11 may be a single-layer elastic belt, may be an elastic belt using a part of the elastic belt, or a conventionally used fluorine-based resin, polycarbonate resin, or polyimide resin. Or an inelastic belt may be used.

  The photosensitive drums 20Y, 20C, 20M, and 20BK are arranged in this order from the upstream side in the A1 direction. Each of the photosensitive drums 20Y, 20C, 20M, and 20BK has image stations 60Y, 60C, 60M, which are toner image forming units as image forming units, for forming yellow, cyan, magenta, and black images, respectively. 60BK is provided.

  The image forming apparatus 100 includes four image stations 60Y, 60C, 60M, and 60BK that are opposed to each other above the photosensitive drums 20Y, 20C, 20M, and 20BK, and serve as a belt unit that includes the transfer belt 11. A transfer belt unit 10 is a paper transfer belt as a transfer member that is disposed to face the transfer belt 11 and is in contact with the transfer belt 11 and rotates in the same direction as the transfer belt 11 at a contact position with the transfer belt 11. A secondary transfer belt unit 5 having a secondary transfer belt 5a, and a cleaning device 13 as an intermediate transfer belt cleaning device, which is an intermediate transfer cleaning blade disposed opposite to the transfer belt 11 and cleaning the surface of the transfer belt 11. , Arranged below the image stations 60Y, 60C, 60M, 60BK. And a light scanning unit 8 as the optical writing device.

  The image forming apparatus 100 also includes a sheet feeding device 61 as a sheet feeding cassette on which the transfer sheets S transported between the photosensitive drums 20Y, 20C, 20M, and 20BK and the transfer belt 11 are stacked, and a sheet feeding apparatus. Each of the photosensitive drums 20Y, 20C, 20M, and 20BK and the transfer belt are fed at a predetermined timing in accordance with the toner image formation timing of the recording paper S conveyed from the feeding device 61 by the image stations 60Y, 60C, 60M, and 60BK. 11 includes a registration roller pair 4 that feeds toward the transfer portion 11 and a sensor (not shown) that detects that the leading edge of the transfer sheet S has reached the registration roller pair 4.

  The image forming apparatus 100 also includes a fixing device 6 as a roller fixing type fixing unit for fixing the toner image to the transfer sheet S to which the toner image is transferred, and the fixed transfer sheet S of the image forming apparatus 100. A paper discharge roller 7 that discharges to the outside of the main body, a paper discharge tray 17 that is disposed on the top of the main body of the image forming apparatus 100 and loads the transfer paper S discharged to the outside of the main body of the image forming apparatus 100 by the discharge roller 7, The toner bottles 9Y, 9C, 9M, and 9BK, which are located below the paper tray 17 and filled with toners of yellow, cyan, magenta, and black, and the back side of the main body of the image forming apparatus 100, as indicated by the alternate long and short dash lines, The toner hoppers 16Y, 16C, 16M, and 16BK are located on the back side in FIG.

  In addition to the transfer belt 11, the transfer belt unit 10 includes primary transfer rollers 12Y, 12C, 12M, and 12BK, and a driving roller 72 that is a driving member as a plurality of winding members around which the transfer belt 11 is wound. The transfer entrance roller 73, the tension roller 74, the cleaning counter roller 76, the spring 75 as a biasing unit that biases the tension roller 74 in the direction of increasing the tension of the transfer belt 11, and the image forming apparatus main body 100 are detachable. And an intermediate transfer belt case 14 for holding a driving roller 72, a transfer inlet roller 73, a tension roller 74, a cleaning counter roller 76, a spring 75, and the like.

The tension roller 74 has a function of applying a predetermined tension suitable for transfer to the transfer belt 11 by the action of the spring 75.
The transfer belt unit 10 can be detached from the image forming apparatus 100 main body toward the front side in FIG. 1 and can be attached to and detached from the image forming apparatus 100 main body.
The transfer belt unit 10, the secondary transfer belt unit 5, and the cleaning device 13 constitute a transfer device 71.

  The sheet feeding device 61 is disposed at the lower part of the main body of the image forming apparatus 100, and includes a feeding roller 3 as a feeding roller that contacts the upper surface of the uppermost transfer sheet S. The uppermost transfer sheet S is fed toward the registration roller pair 4 by being rotationally driven 3 in the counterclockwise direction.

  The secondary transfer belt unit 5 includes a secondary transfer belt 5a, a secondary transfer roller 5b around which the secondary transfer belt 5a is wound, and driven rollers 5c and 5d. The secondary transfer roller 5b is urged toward the driving roller 72 by an urging unit (not shown), and for transferring the toner image on the transfer belt 11 onto the transfer sheet S by a bias application unit (not shown). A bias is applied. The driven roller 5c is located in the vicinity of the fixing device 6, and the toner image on the transfer belt 11 is transferred by the portion of the secondary transfer belt 5a that is stretched between the secondary transfer roller 5b and the driven roller 5c. The transferred transfer paper S is conveyed toward the fixing device 6.

The fixing device 6 includes a fixing roller 62 having a heat source therein and a pressure roller 63 pressed against the fixing roller 62. The fixing sheet 62 carrying the toner image is transferred to the fixing roller 62 and the pressure roller 63. By passing through a fixing portion that is a pressure contact portion, the carried toner image is fixed on the surface of the transfer paper S by the action of heat and pressure.
The optical scanning device 8 includes light emitting elements 8Y, 8C, 8M, and 8BK for exposing the photosensitive drums 20Y, 20C, 20M, and 20BK, and forming an electrostatic latent image, respectively.

  The yellow, cyan, magenta, and black toners filled in the toner bottles 9Y, 9C, 9M, and 9BK are supplied to the toner hoppers 16Y, 16C, 16M, and 16BK, respectively. The toner stored in the toner hoppers 16Y, 16C, 16M, and 16BK is replenished by a predetermined replenishment amount to the developing devices 50Y, 50C, 50M, and 50BK provided in the image stations 60Y, 60C, 60M, and 60BK, respectively. The

  Regarding the image stations 60Y, 60C, 60M, and 60BK, the configuration will be described as a representative of the configuration of the image station 60Y including the photosensitive drum 20Y. Since the configuration of the other image station is substantially the same, in the following description, for the sake of convenience, a reference numeral corresponding to the reference symbol assigned to the configuration of the image station 60Y is attached to the configuration of the other image station. Further, detailed description will be omitted as appropriate, and those with Y, C, M, K at the end of the reference numerals are configurations for forming yellow, cyan, magenta, and black images, respectively. Will be shown.

  As shown in FIG. 2, the image station 60Y including the photosensitive drum 20Y includes a primary transfer roller 12Y and a photosensitive member around the photosensitive drum 20Y along a rotation direction B1 that is a clockwise direction in the drawing. A cleaning device 40Y as a cleaning unit for cleaning the drum 20Y, a charging unit 30Y as a charging unit as a charging unit for charging the photosensitive drum 20Y, and a developing unit for developing the photosensitive drum 20Y A developing device 50Y which is a developing unit.

The cleaning device 40Y includes a cleaning case 43Y having an opening at a portion facing the photoconductor drum 20Y, a base end portion fixed to the cleaning case 43Y, and a tip portion abutting on the photoconductor drum 20Y so as to be transferred onto the photoconductor drum 20Y. A cleaning blade 41Y for scraping and cleaning residual toner such as residual toner and a cleaning case 43Y are rotatably supported by the cleaning blade 41Y, and the residual toner scraped off by the cleaning blade 41 is conveyed toward a waste toner bottle (not shown). For example, a waste toner screw 42Y.
In this embodiment, a cleaning method that performs cleaning using the cleaning blade 41Y is employed, but a blade rescreening method that performs cleaning using a brush may be employed.

  The charging device 30Y includes a charging roller 31Y that rotates in contact with the surface of the photoreceptor drum 20Y, and a cleaning roller 32Y that rotates in contact with the charging roller 30Y. The charging roller 31Y is connected to a voltage applying means (not shown) for applying a bias of an alternating current component to a direct current, and in the charging region facing the photosensitive drum 20Y, the surface of the photosensitive drum 20Y is neutralized at the same time as the charging roller 31Y. The polarity is charged.

The cleaning roller 32Y is driven to rotate by following the charging roller 30Y to clean the charging roller 30Y.
As described above, in this embodiment, the charging system using the contact roller is adopted, but the charging system may be one using a proximity roller or one using a corotron system. .

A predetermined voltage suitable for primary transfer is applied to the primary transfer roller 12Y by a voltage application unit (not shown).
As shown in FIG. 2, the light emitting element 8Y shown in FIG. 1 irradiates light modulated laser light L to a region between the charging region and the developing region of the photosensitive drum 20Y, and is defined by the charging roller 30Y. The surface of the photosensitive drum 20Y after being uniformly charged to the potential is exposed to form an electrostatic latent image that is visualized as a yellow toner image by the developing device 50Y.

  Of the photoconductor drum 20Y, the primary transfer roller 12Y, the cleaning device 40Y, the charging device 30Y, and the developing device 50Y constituting the image station 60Y, excluding the primary transfer roller 12Y, that is, the photoconductor drum. 20Y, the cleaning device 40Y, the charging device 30Y, and the developing device 50Y constitute a process cartridge 95Y that is a process unit as a unit. The process cartridge 95Y is integrated with the image forming apparatus 100 main body. It is detachable to the front side in FIG. 1 and is detachable.

  In addition, the photosensitive drum 20Y is detachable from the image forming apparatus 100 main body on the front side in FIG. 1, and is detachable, and also constitutes a process cartridge 95Y. Of the cleaning device 40Y, the charging device 30Y, and the developing device 50Y, the one excluding the photosensitive drum 20Y, that is, the cleaning device 40Y, the charging device 30Y, and the developing device 50Y constitute a unit. The unit is integrated, and is detachable from the image forming apparatus 100 main body toward the front side of the sheet in FIG. 1, and is detachable.

  Further, the developing device 50Y alone is detachable from the image forming apparatus 100 main body in the front side of the sheet in FIG. 1, is detachable, and also constitutes a process cartridge 95Y. Of the cleaning device 40Y, the charging device 30Y, and the developing device 50Y, the one excluding the developing device 50Y, that is, the photosensitive drum 20Y, the cleaning device 40Y, and the charging device 30Y constitute a unit. The unit is integrated, and is detachable from the image forming apparatus 100 main body toward the front side in FIG.

  2, 3, or 5, the developing device 50 </ b> Y includes a developing case 55 </ b> Y that is a casing as a developer container having an opening in a portion facing the photoconductor drum 20 </ b> Y, and a photoconductor from the opening. A developing roller 51Y as a developing member disposed close to and facing the photosensitive drum 20Y so as to face the drum 20Y, a developing blade 52Y that regulates the developer on the developing roller 51Y to a certain height, and a developing case 55Y The first conveying screw 53Y as a first conveying member that is a conveying member and the second conveying that is a conveying member that are arranged to face each other and agitate while conveying the developer in a circulating manner. Included in the developer in the developing case 55Y, a second stirring screw 54Y as a member, a bias applying means (not shown) for applying a developing bias of a direct current component And toner concentration detecting means (not shown) for detecting that toner density, and a magnet 90 such as a magnetic field generating means.

The developing device 50Y performs development using a developer as a two-component developer containing a yellow toner as a non-magnetic toner and a magnetic carrier.
As shown in FIG. 2 or FIG. 5, the developing roller 51Y is rotatable and has a sleeve 56Y as a developing sleeve made of a nonmagnetic material carrying a developer on its surface, and is fixedly disposed inside the sleeve 56Y. The sleeve 56Y includes a magnet 57Y that generates a magnetic field for supporting the developer.

  As shown in FIG. 2, FIG. 3, or FIG. 5, the developing case 55 </ b> Y includes a developing chamber 58 </ b> Y that accommodates the first transport screw 53 </ b> Y, an agitation chamber 59 </ b> Y that accommodates the second transport screw 54 </ b> Y, A partition wall 81Y for partitioning and partitioning 59Y and a supply port 91Y for receiving toner from the toner hopper section 16Y shown in FIGS. 3, 4, and 6 are provided. Since the first conveying screw 53Y faces the developing roller 51Y so as to supply the developer to the developing roller 51Y, the developing chamber 58Y is positioned closer to the developing roller 51Y in the developing chamber 58Y and the stirring chamber 59Y. doing.

  The first transport screw 53Y and the second transport screw 54Y are respectively provided with screw shafts 85Y and 86Y formed by rotation shafts 83Y and 84Y forming a rotation center, and spiral protrusions formed on the rotation shafts 83Y and 84Y. have. The first transport screw 53Y and the second transport screw 54Y are disposed in parallel to each other and in parallel to the developing roller 51Y.

  The first conveyance screw 53Y and the second conveyance screw 54Y are rotated around the rotation shafts 83Y and 84Y, respectively, and the rotation shaft directions, that is, the rotation shafts 83Y and 84Y extend by the action of the screw portions 85Y and 86Y. The developer is conveyed in a direction perpendicular to the paper surface in FIG.

  As shown by the arrows in FIG. 2, the rotation directions of the first conveyance screw 53Y and the second conveyance screw 54Y are opposite to each other, and the developer conveyance directions are also opposite to each other. Therefore, the developer is transported so as to circulate in a certain direction by the rotation of the first transport screw 53Y and the second transport screw 54Y.

  In the developing device 50Y, the developer in the developing chamber 58Y is carried in a spike shape on the developing sleeve 56Y by the magnetic force of the magnet 57Y, and the amount of developer carried by the developing sleeve 56Y is regulated by the developing blade 52Y. . The layered developer that is regulated and has an appropriate amount on the developing sleeve 56Y is developed in the developing region between the developing roller 51Y and the photosensitive drum 20Y by the rotation of the developing sleeve 56Y in the direction of the arrow C1 and the developing bias by the bias applying means. The yellow toner in the developer is electrostatically transferred to the electrostatic latent image formed on the surface of the photosensitive drum 20Y, and the electrostatic latent image is visualized as a yellow toner image. It has become.

  The toner density detecting means detects the toner density contained in the developer in the developing case 55Y. When the toner density falls below a predetermined density, an appropriate amount of yellow toner is replenished and supplied from the toner hopper 16Y through the supply port 91Y. The supplied yellow toner and developer are agitated and mixed by the first conveying screw 53Y and the second agitating screw 54Y, and the agitated and mixed developer is supplied to the developing roller 51Y.

  As shown in FIG. 4, a coil 80Y is provided in the toner hopper portion 16Y, and the toner concentration detection means causes the toner concentration contained in the developer in the developing case 55Y to fall below a predetermined concentration. In addition, the coil 80Y is rotationally driven, and an appropriate amount of yellow toner is supplied and supplied from the toner hopper 16Y to the developing device 50Y through the supply port 91Y. Such a configuration is the same in the other toner hoppers 16C, 16M, and 16BK.

  The toner supplied into the main body of the developing device 50Y through the supply port 91Y falls on the second transport screw 54Y. That is, the supply port 91Y is disposed at a position where the toner is supplied to the second transport screw 54Y. This is because if the toner is directly supplied to the first conveying screw 53Y, the toner is supplied to the developing roller 57Y without being sufficiently agitated with the developer, resulting in problems such as uneven development. Since the supply port 91Y is disposed at a position where the toner is supplied to the second conveying screw 54Y, the supplied toner is agitated before reaching the developing roller 57Y.

  However, since the replenished toner can only be moved on a macroscopic scale by simply stirring the toner and developer with the first transport screw 53Y and the second transport screw 54Y, it is originally circulated in the developing device 50Y. Replenished toner because it is difficult to quickly loosen the agglomerated toner while it is only transported in a floating state in a state of being agglomerated to a size of several microns on the developer. Is not sufficiently dispersed, so that the replenished toner is not uniformly dispersed in the developer, and it is impossible to obtain a state in which all of the replenished toner is in contact with the magnetic carrier. Continuing to be conveyed in a rubbing state, a toner with a charged charge near 0 and insufficiently charged, and a toner charged with a reverse polarity are produced, and sufficient chargeability at a desired polarity Can not be ensured, failure or the like uneven development such white head on a formed image, machine contamination due to toner scattering, which may cause a problem of image dirt.

  The magnet 90Y is provided to prevent such a problem. The magnet 90Y acts on the magnetic carrier contained in the developer conveyed by the second conveying screw 54Y. As shown in FIG. 3 or FIG. 5, the magnetic carrier is attracted by the action of the generated magnetic field. The developer spike 92Y, which is a developer lump, is formed, and the replenished and conveyed toner is pressed against the spike, so that the replenished toner lump is broken, stirred and mixed, and uniformly dispersed. . This is excellent in that the charge distribution of the toner becomes sharp and partial transfer omission in image formation is prevented.

  The magnet 90Y is disposed above the second conveying screw 54Y and integrated with the developing case 55Y so as to be fitted onto the upper surface of the developing case 55Y. For this reason, unlike the case where it is located below or to the side of the second transport screw 54Y, the distance from the supply port 91Y or the supply port of the toner to the second transport screw 54Y from the supply port 91Y is relatively short. The developer ear 92Y that can sufficiently secure the dispersion of the toner can be formed without using a material having a stronger magnetic force as the rotational torque of the two conveying screw 54Y increases.

  When the arrangement position of the magnet 90Y is further described, as shown in FIG. 5 or FIG. 6, the magnet 90Y supplies toner to the second conveyance screw 54Y from the supply port 91Y in the rotation direction of the second conveyance screw 54Y. The second conveyance screw 54Y from the supply port 91Y in the vicinity of the downstream side of the position, specifically, the position on the right side of the center of the shaft 84Y in FIG. 5 in the conveyance direction of the developer by the second conveyance screw 54Y. Is disposed corresponding to a position downstream of the toner supply position. This makes it possible to efficiently and reliably disperse the toner by the developer ear 92Y while reducing the size of the magnet 90Y and suppressing an increase in the size of the developing device 50Y.

  However, when the magnet 90Y is used, it is considered that the developer is hardly exchanged at the base of the formed developer head 92Y and the circulation is not sufficient regardless of the position of the magnet 90Y. Therefore, in order to improve the circulation of the developer also in the root portion of the developer ear 92Y formed by the magnet 90Y, as shown in FIGS. 5 to 7, the rotating shaft 84Y has a development formed by the magnet 90Y. It has a scraping member 93Y that scrapes off the agent ear 92Y.

  The scraping member 93Y is formed so as to protrude from the rotation shaft 84Y. In this embodiment, the scraping member 93Y is integrally formed at the time of forming the rotating shaft 84Y from the viewpoint of efficiency of formation and cost reduction, but may be attached to the rotating shaft 84Y after the forming of the rotating shaft 84Y. Since the scraping member 93Y is integral with the rotation shaft 84Y, when the rotation shaft 84Y rotates, the scraping member 93Y also rotates integrally with the rotation shaft 84Y.

  In this embodiment, since the magnet 90Y and the stirring chamber 59Y are separated from each other by the developing case 55Y, the developer ear 92Y formed by the magnet 90Y is attached to the developing case 55Y. Is also attached to the developing case 55Y. Therefore, the scraping member 93Y has substantially the same width as the width of the magnet 90Y in the rotation axis direction at the position substantially the same as the position occupied by the magnet 90Y in the rotation axis direction of the second transport screw 54Y so as to interfere with the root. And has a size in contact with the developing case 55Y when it comes to a position closest to the magnet 90Y, that is, a position just above the rotation shaft 84Y. Thus, the scraping member 93Y is excellent from the viewpoint of improving the circulation of the developer when the developing case 55Y serves as a partition wall and is separated from the magnet 90Y so as to contact the developing case 55Y. However, as long as the circulation of the developer can be improved, the developer may be brought close to the developing case 55Y.

  In this embodiment, as shown in FIG. 8A, the developing case 55Y that forms a partition wall between the scraping member 93Y and the magnet 90Y has a flat shape that separates the scraping member 93Y and the magnet 90Y. Since the shape is the flat surface portion 94Y, the scraping member 93Y can only interfere with a part of the root of the developer ear 92Y attached to the developing case 55Y. In order for the scraping member 93Y to interfere with the entire root of the developer ear 92Y in the state of being attached to the developing case 55Y, the portion of the developing case 55Y to which the developer ear 92Y has adhered is shown in FIG. ), It is desirable that the tip of the scraping member 93Y is a portion having a shape along a locus drawn by the rotation of the second conveying screw 54Y, that is, an arc-shaped portion 89Y having an arc shape.

  In this embodiment, the developing case 55Y is located between the scraping member 93Y and the magnet 90Y to form a partition wall. However, as shown in FIG. 9, the magnet 90Y faces the stirring chamber 59Y and scrapes off. The member 93Y may be exposed. In this case, as shown in FIG. 9A, when the shape of the portion facing the scraping member 93Y is a flat planar portion 96Y, the scraping member 93Y adheres to the magnet 90Y. Since the scraping member 93Y can interfere with only a part of the root of the developer ear 92Y in a state of being removed, the scraping member 93Y interferes with the entire root of the developer ear 92Y in a state of being attached to the developing case 55Y. As shown in FIG. 9B, the portion of the magnet 90Y to which the developer ear 92Y is attached is a portion in which the tip of the scraping member 93Y forms a shape along the locus drawn by the rotation of the second transport screw 54Y. It is desirable that the arc portion 97Y has an arc shape.

  As shown in FIG. 9, when the magnet 90Y is exposed to the scraping member 93Y, when the scraping member 93Y comes closest to the magnet 90Y so as to interfere with the root of the developer ear 92Y, the magnet Although it is desirable to have a size in contact with 90Y, as long as the developer can be circulated favorably, the size may be close to the magnet 90Y.

  As described above, the second transport screw 54Y has the rotating shaft 84Y and the screw portion 86Y, and transports the developer in a certain direction by the action of the screw portion 86Y. However, as is apparent from FIGS. 6 and 7, the screw portion 86Y is disposed in an interrupted manner at the position where the scraping member 93Y is disposed in the rotational axis direction of the second transport screw 54Y. The scraping member 93Y has an action of stirring the developer in the rotation direction thereof, but is not expected to have a function of conveying the developer in the rotation axis direction of the second conveyance screw 54Y. Accordingly, the developer stays in the stirring chamber 59Y at the position where the scraping member 93Y is disposed in the direction of the rotation axis of the second transport screw 54Y, which may adversely affect good development.

  Therefore, as shown in FIGS. 3, 6, and 7, the pitch of the screw part 86Y is larger than that of the screw part 98Y on the upstream side of the scraping member 93Y in the developer conveying direction by the second conveying screw 54Y. The screw portion 99Y on the downstream side is larger. As described above, the developer conveying speed of the second conveying screw 54Y is higher on the downstream side than the upstream side in the developer conveying direction with respect to the arrangement position of the scraping member 93Y. Therefore, since the developer is quickly transported downstream of the scraping member 93Y in the developer transport direction by the second transport screw 54Y, the developer stays at the position where the scraping member 93Y is disposed or in the vicinity thereof. The developer always circulates well in the developing device 50Y, and the development is performed well.

  The pitch of the screw part 85Y and the pitch of the screw part 99Y are the same, and the developer conveyance speeds of these parts are the same. However, the pitch of the screw portion 85Y is intermediate between the pitch of the screw portion 98Y and the pitch of the screw portion 99Y, and the developer conveyance speed in the screw portion 85Y portion is the developer conveyance speed in the screw portion 98Y portion. It is good also as an intermediate | middle with the conveyance speed of the developer in the screw part 99Y.

Further, in order to increase / decrease the developer conveying speed by the second conveying screw 54Y, in place of increasing / decreasing the pitch of the screw portion 86Y or by adjusting the pitch of the screw portion 86Y, the screw portion 86Y is formed. The height of the protruding shape may be adjusted.
In the developing device 50Y of the present embodiment, the DC component developing bias is applied by the bias applying unit. However, the developing bias may be an AC component, or an AC component superimposed on the DC component. May be.

  With the configuration as described above, the surface of the photosensitive drum 20Y is uniformly charged by the charging roller 31Y as it rotates in the B1 direction, and corresponds to the yellow color by exposure scanning of the laser light L from the light emitting element 8Y. An electrostatic latent image is formed, this electrostatic latent image is developed with yellow toner by the developing device 50Y, and the yellow visible toner image obtained by development is moved in the A1 direction by the primary transfer roller 12Y. The foreign matter such as toner that is primarily transferred to the transfer belt 11 and remains after the transfer is removed by the cleaning device 40Y, and is used for the next charge removal and charging by the charging roller 31Y.

Similarly, toner images of the respective colors are formed on the other photosensitive drums 20C, 20M, and 20BK, and the formed toner images of the respective colors are transferred to the A1 direction by the primary transfer rollers 12C, 12M, and 12BK. 11 is sequentially transferred to the same position on the head. The development for forming these color toner images is performed well because the toner is well stirred, mixed, and dispersed.
The toner image superimposed on the transfer belt 11 moves to the transfer portion which is the secondary transfer portion which is the position facing the secondary transfer belt unit 5 as the transfer belt 11 rotates in the A1 direction. 2 is secondarily transferred to the transfer paper S.

  The transfer sheet S conveyed between the transfer belt 11 and the secondary transfer belt unit 5 is fed out and fed from the sheet feeding device 61 by the feeding roller 3, and a detection signal from the sensor by the registration roller pair 4. The leading edge of the toner image on the transfer belt 11 is sent out at a timing facing the secondary transfer roller 5.

  When the transfer paper S is transferred and carried all the toner images of all colors, it is transported by the secondary transfer belt unit 5 and enters the fixing device 6, and a fixing portion between the fixing roller 62 and the pressure roller 63. When the toner passes through the toner image, the carried toner image is fixed by the action of heat and pressure. By this fixing process, a color image which is a composite color image is formed on the transfer paper S, and a permanent image is obtained. The fixed transfer paper S that has passed through the fixing device 6 passes through the paper discharge roller 7 and is stacked on the paper discharge tray 17 at the top of the main body of the image forming apparatus 100. On the other hand, the transfer belt 11 that has finished the secondary transfer is cleaned by the cleaning device 13 to prepare for the next development process by the image station.

  As described above, the image forming apparatus 100 to which the present invention is applied has been described as an embodiment for carrying out the present invention. However, the shape of the conveying member is as described above as long as the developer is conveyed in the rotation axis direction by rotation. In this case, a configuration including a plurality of inclined plates inclined with respect to the rotation axis direction may be used, and in this case, in order to increase or decrease the developer transport speed, What is necessary is just to adjust the arrangement | positioning space | interval and magnitude | size.

The process cartridge that is detachable from the image forming apparatus main body includes at least one of a developing device, an image carrier, a charging unit for charging the image carrier, and a cleaning unit for cleaning the image carrier. As long as it is provided with a unit.
The application of the present invention is not limited to the above-described embodiment unless particularly limited in the above description.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic front view showing a process cartridge provided in the image forming apparatus shown in FIG. 1. FIG. 3 is a schematic perspective view of an internal structure of a developing device provided in the process cartridge shown in FIG. 2. FIG. 2 is a schematic side view showing a structure for supplying toner to a developing device provided in the image forming apparatus shown in FIG. 1. FIG. 3 is a schematic front view of an internal structure of a developing device provided in the process cartridge shown in FIG. 2. FIG. 3 is a schematic plan sectional view of a developing device provided in the process cartridge shown in FIG. 2. FIG. 3 is a schematic perspective view showing a part of a developing device provided in the process cartridge shown in FIG. 2 in an enlarged manner. FIG. 2 is a schematic cross-sectional view showing a configuration aspect and an arrangement aspect of a magnetic field generation unit provided in a developing device to which the present invention is applied. It is a schematic sectional drawing which shows another arrangement | positioning aspect of the magnetic field generation means with which the image development apparatus to which this invention is applied was equipped.

Explanation of symbols

20Y, 20C, 20M, 20BK Image carrier 30Y, 30C, 30M, 30BK Charging unit 40Y, 40C, 40M, 40BK Cleaning unit 51Y Developing member 53Y Conveying member, first conveying member 54Y Conveying member, second conveying member 55Y Member constituting partition wall between magnetic field generating means and scraping member 89Y Shape of partition wall along the locus drawn by the rotation of the second conveying member of the scraping member 90Y Magnetic field generating means 91Y Supply port 92Y Developer Lump 93Y scraping member 95Y, 95C, 95M, 95BK process cartridge 97Y shape of magnetic field generating means along the trajectory drawn by the rotation of the second conveying member at the tip of the scraping member 100 image forming apparatus

Claims (11)

  A conveying member that conveys a developer containing toner and a magnetic carrier in the direction of the rotation axis by rotation, a magnetic field generating unit that is disposed near the conveying member and generates a magnetic field, and a development formed by the magnetic field generating unit A developing device having a scraping member that scrapes off a lump of the agent.   2. The developing device according to claim 1, wherein the conveying member is opposed to the first conveying member disposed opposite to the developing member disposed opposite to the image carrier, and to the first conveying member. And a second transporting member disposed in such a manner.   3. The developing device according to claim 2, wherein a supply port for supplying toner into the developing device main body is disposed at a position where the toner is supplied to the second transport member.   4. The developing device according to claim 3, wherein the magnetic field generating unit is positioned downstream of the supply position of the toner from the supply port to the second transport member in the developer transport direction by the second transport member. A developing device, wherein the developing device is disposed corresponding to a position in the vicinity of a downstream side of a supply position of toner from the supply port to the second conveying member in the rotation direction of the second conveying member. .   5. The developing device according to claim 2, wherein the scraping member is integrated with the second transport member. 6.   6. The developing device according to claim 5, wherein the scraping member is in contact with the magnetic field generating means when the second conveying member is rotated and the magnetic field generating means is exposed to the scraping member, or A developing device characterized in that when there is a partition between the magnetic field generating means and the scraping member, the developer lump is scraped off by contacting or approaching the partition.   7. The developing device according to claim 5, wherein when the magnetic field generating means is exposed to the scraping member, the magnetic field generating means has a tip of the scraping member at the second end. When the conveying member has a portion formed along a locus drawn by the rotation of the conveying member, and there is a partition between the magnetic field generating means and the scraping member, the partition is the second end of the scraping member. A developing device comprising a portion having a shape along a locus drawn by rotation of the conveying member.   8. The developing device according to claim 2, wherein the second conveying member is developed on the downstream side of the developer conveying direction on the downstream side with respect to the arrangement position of the scraping member. A developing device having a shape in which the conveying speed of the agent is increased.   9. The developing device according to claim 1, wherein the magnetic field generating means is disposed above the conveying member.   10. The developing device according to claim 1, and at least one of an image carrier, a charging unit for charging the image carrier, and a cleaning unit for cleaning the image carrier. And a process cartridge that is detachable from the image forming apparatus main body. An image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 10.

Images