JP2014115519A - Developing apparatus, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing apparatus for reliably preventing scattering of suspended toner, while preventing melting of toner, and an image forming apparatus and a process cartridge.SOLUTION: A developing apparatus includes a rotatable toner collection member 13 which is arranged downstream of a developing region, where a developer carrier 5 faces an image carrier 1, in a surface moving direction of the image carrier 1, to collect toner suspended in a developing apparatus 4. At least one of a plurality of magnetic poles of the developer carrier 5 is arranged in a position facing the toner collection member 13 so as to form a magnetic field to brush a developer. The toner collection member 13 is arranged in contact with the developer brushed with the magnetic field by at least one of the magnetic poles, so as not to come into contact with any of a surface of the developer carrier 5 or a surface of the image carrier 1.

Description

  The present invention relates to a developing device using a developer containing toner and a carrier, an image forming apparatus including the developing device, and a process cartridge.

  Conventionally, as this type of developing device, in order to prevent toner floating in the developing device (toner cloud) from flowing out of the developing device and scattering, the floating toner floating in the developing device is collected. One having a toner collection roller is known. For example, Patent Document 1 discloses a developing device that includes a toner collection roller that is rotationally driven so as to attract and collect floating toner in the developing device on the outer peripheral surface at a position close to the developing sleeve. In this developing device, a thin plate scraper is brought into contact with the outer peripheral surface of the toner collecting roller to scrape and remove the toner adsorbed on the outer peripheral surface of the toner collecting roller. By removing the toner from the outer peripheral surface of the toner collecting roller in this way, toner leakage from the bearings at both ends in the axial direction of the toner collecting roller can be prevented, or toner contamination on the outer peripheral surface of the toner collecting roller can be removed. Therefore, toner scattering can be prevented more reliably. As a member for scraping off the toner from the toner collecting roller, there is also known a member using an elastic foam material in addition to the above-described thin scraper.

  However, as in the developing device disclosed in Patent Document 1, in a configuration in which a scraper or a foam material is brought into contact with the outer peripheral surface of the toner recovery roller and the toner collected and collected on the outer peripheral surface is scraped, the toner recovery roller that is driven to rotate. Heat is generated by friction between the outer peripheral surface of the steel and the scraper. This heat generation causes a problem that the toner collected by adsorption on the outer peripheral surface of the toner collecting roller is melted. The melting of the toner causes a failure of the developing device, which may impair the high durability and high reliability of the image forming apparatus including the developing device.

  In particular, in recent years, the melting point has a lower melting point than conventional toners and can be fixed at a low temperature in order to drive the developing roller at a high speed in order to increase the speed of the image forming apparatus and to reduce the fixing energy to reduce the environmental load. Fixing toner has been used. In addition, high durability and high reliability are required to minimize downtime due to equipment failure. That is, when the developing roller is driven at a high speed, the amount of toner floating inside the developing device increases, and the amount of toner that is attracted and collected on the outer peripheral surface of the toner collecting roller increases. For this reason, in order to scrape more toner from the outer peripheral surface of the toner recovery roller, the toner recovery roller must be rotated faster, and the scraper or foam that is in contact with the outer peripheral surface of the toner recovery roller The amount of heat generated by friction with the material increases. In addition, the low-temperature fixing toner has a lower melting point than that of the conventional toner, and is thus easily melted. For this reason, more toner may be melted in the developing device.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device capable of reliably preventing toner scattering while avoiding melting of the toner, and an image forming apparatus including the developing device, and A process cartridge is provided.

  In order to achieve the above-mentioned object, the invention according to claim 1 is a developer carrying system comprising a plurality of magnetic poles on which a surface carrying a developer containing toner and a magnetic carrier is configured to be movable. A developing device that develops a latent image formed on the image carrier by transporting a developer carried on the surface of the developer carrier to a development area facing the image carrier. A developer collecting member provided on the downstream side of the developing region in the moving direction of the surface of the image carrier and having a rotatable toner collecting member for collecting the floating toner floating in the developing device; At least one of the plurality of magnetic poles of the toner collecting member is provided so as to form a magnetic field that causes the developer to rise at a position facing the toner collecting member, and the toner collecting member includes: a surface of the developer carrying member; Of the image carrier And is characterized in that it is arranged to contact the developer was allowed to napping in the magnetic field due and the at least one magnetic pole so as not to contact with any surface.

  According to the present invention, the rotatable toner collecting member is provided on the downstream side in the surface moving direction of the image carrier from the developing region. With this toner collecting member, the floating toner floating in the developing device can be collected, so that the floating toner can be prevented from scattering. Further, at least one of the plurality of magnetic poles of the developer carrying member is provided so as to form a magnetic field for causing the developer to spike at a position facing the toner collecting member. Further, the toner recovery member is disposed at a position in contact with the developer spiked by the magnetic field generated by the at least one magnetic pole. The spiked developer rubs the surface of the rotating toner collecting member, so that the collected toner attached to the surface of the toner collecting member can be removed. As a result, the toner contamination on the surface of the toner collecting member can be removed and the floating toner collecting function of the toner collecting member can be maintained, so that toner scattering can be more reliably prevented. In addition, since the toner collecting member is arranged so as not to contact either the surface of the developer carrier or the surface of the image carrier, frictional heat is generated by the contact of the surface of the developer carrier and the like. Therefore, toner melting due to the frictional heat can be avoided. Therefore, it is possible to reliably prevent the toner from scattering while avoiding melting of the toner.

1 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention. FIG. 2 is an enlarged configuration diagram illustrating a developing device and a photoreceptor according to the present embodiment. FIG. 4 is a partial perspective view of the developing device showing a flow of the developer in the developer conveyance path. FIG. 3 is an external perspective view illustrating a position where toner is supplied from a developing device. FIG. 3 is a partially enlarged view of a main part where a developing roller and a toner collecting roller are opposed to each other. FIG. 3 is a schematic configuration diagram illustrating a configuration example of a driving unit of a toner collection roller. FIG. 4 is an explanatory diagram for explaining toner removal from a toner collecting roller. FIG. 10 is a partially enlarged view showing a configuration of a developing device according to a conventional example.

  An embodiment in which the present invention is applied to an electrophotographic color copying machine (hereinafter referred to as “copying machine”) as an image forming apparatus will be described below. In this embodiment, the case of a copying machine will be described. However, the present invention can be applied not only to a copying machine but also to other image forming apparatuses including a developing device such as a printer, a facsimile machine, and a multifunction machine. .

  FIG. 1 is a schematic configuration diagram of a copier 500 according to the first embodiment of the present invention. In FIG. 1, a copier 500 includes a printer unit 100 as an image forming unit, a paper feeding device 200 as a recording medium supply unit that supplies transfer paper as a recording medium to the printer unit 100, and the like. Further, the copying machine 500 includes a scanner 300 as image reading means fixed on the printer unit 100, and an automatic document feeder 400 is fixed on the scanner 300.

  The printer unit 100 includes an image forming unit including four sets of process cartridges 18Y, 18M, 18C, and 18K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). 20 is provided. Y, M, C, and K added after the numerals of the respective symbols indicate members for yellow, magenta, cyan, and black (the same applies hereinafter). In addition to the process cartridges 18Y, 18M, 18C, and 18K, the printer unit 100 includes an optical writing unit 21 as a latent image writing unit, an intermediate transfer unit 17, a secondary transfer device 22, a registration roller pair 49, a belt fixing system. The fixing device 25 is provided.

  The optical writing unit 21 includes a light source (not shown), a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of a later-described photosensitive member 1 as an image carrier based on image data with laser light.

  Each of the process cartridges 18Y, 18M, 18C, and 18K includes a drum-shaped photosensitive member 1 as an image carrier, a charging device as a charging unit that charges the surface of the photosensitive member 1, and a latent image formed on the photosensitive member 1. And a developing device 4 as developing means for developing the toner. Further, each of the process cartridges 18Y, 18M, 18C, and 18K includes a drum cleaning device as an image carrier cleaning unit that cleans the surface of the photoconductor 1, a static eliminator as a static elimination unit that neutralizes the surface of the photoconductor 1, and the like. ing. Since the process cartridges 18Y, 18M, 18C, and 18K have the same configuration, the process cartridge 18Y for yellow will be described below.

  The surface of the photoreceptor 1Y is uniformly charged by the charging device. The surface of the photoreceptor 1Y that has been subjected to the charging process is irradiated with laser light that is modulated and deflected by the optical writing unit (exposure device) 21. Thereby, the potential of the surface of the photoreceptor 1Y of the irradiation part (exposure part) is attenuated. Due to the attenuation of the surface potential, an electrostatic latent image for Y is formed on the surface of the photoreceptor 1Y. The formed electrostatic latent image for Y is developed by the developing device 4Y to become a Y toner image. The Y toner image formed on the Y photoconductor 1Y is primarily transferred to an intermediate transfer belt 110 as an intermediate transfer member described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device. Further, in the Y process cartridge 18Y, the photoreceptor 1Y cleaned by the drum cleaning device is discharged by the charge eliminator. Then, it is uniformly charged by the charging device and returns to the initial state. The series of processes as described above is the same for the other process cartridges 18M, 18C, and 18K.

Next, the intermediate transfer unit 17 will be described.
The intermediate transfer unit 17 includes an intermediate transfer belt 110 as an intermediate transfer member, a belt cleaning device 60 as an intermediate transfer member cleaning unit that cleans the surface of the intermediate transfer belt 110, and the like. The intermediate transfer unit 17 also includes a stretching roller 14, a drive roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, M, C, and K.

  The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14 so as to have a predetermined tension. The intermediate transfer belt 110 moves endlessly in the clockwise direction in the drawing by the rotation of the driving roller 15 driven by a belt driving motor (not shown).

  The primary transfer bias rollers 62Y, 62M, 62C, and 62K are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, and receive a primary transfer bias from a power source (not shown). Further, the intermediate transfer belt 110 is pressed toward the photoreceptors 1Y, 1M, 1C, and 1K from the inner peripheral surface side to form primary transfer nips. In each primary transfer nip, a primary transfer electric field is formed between the photoreceptor 1 and the primary transfer bias roller 62 due to the influence of the primary transfer bias. The Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 by the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, K toner images formed on the M, C, K photoconductors 1M, C, K are sequentially superposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as “four-color toner image”) as a multiple toner image is formed on the intermediate transfer belt 110.

  The four-color toner image superimposed and transferred onto the intermediate transfer belt 110 is secondarily transferred onto a transfer sheet (not shown) as a recording medium at a secondary transfer nip described later. Transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by a belt cleaning device 60 that sandwiches the belt with the driving roller 15 on the left side in the drawing.

Next, the secondary transfer device 22 will be described.
Below the intermediate transfer unit 17 in the figure, a secondary transfer device 22 is disposed in which a paper conveying belt 24 is stretched by two stretching rollers 23. The paper transport belt 24 moves endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. One of the two stretching rollers 23, that is, the upstream stretching roller 23 arranged on the upstream side (right side in the drawing) in the transfer paper conveyance direction is between the secondary transfer backup roller 16 of the intermediate transfer unit 17. Further, the intermediate transfer belt 110 and the paper transport belt 24 are sandwiched. By this sandwiching, a secondary transfer nip is formed in which the intermediate transfer belt 110 of the intermediate transfer unit 17 and the paper transport belt 24 of the secondary transfer device 22 are in contact with each other. A secondary transfer bias having a polarity opposite to that of the toner is applied to the one (upstream side) stretching roller 23 by a power source (not shown). By applying the secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is applied from the belt side to the one (upstream) stretching roller 23 side in the secondary transfer nip. A secondary transfer electric field to be electrostatically moved is formed. The transfer paper fed into the secondary transfer nip so as to synchronize with the four-color toner image on the intermediate transfer belt 110 by a registration roller pair 49 described later has four colors affected by the secondary transfer electric field and nip pressure. The toner image is secondarily transferred. Instead of the secondary transfer method in which the secondary transfer bias is applied to the one (upstream side) stretching roller 23, a charger for charging the transfer paper in a non-contact manner may be provided.

  In the paper feeding device 200 provided at the lower part of the copying machine 500 main body, a plurality of paper feeding cassettes 44 in which a plurality of transfer sheets can be stacked and stored in a bundle of sheets are arranged so as to overlap each other in the vertical direction. It is installed. Each paper feed cassette 44 presses the paper feed roller 42 against the uppermost transfer paper in the paper bundle. Then, by rotating the paper feed roller 42, the uppermost transfer paper is sent out toward the paper feed path 48.

  The paper feed paths 46 and 48 that receive the transfer paper delivered from the paper feed cassette 44 have a plurality of conveying roller pairs 47 and a registration roller pair 49 provided near the end in the paper feed path 48. . Then, the transfer paper is conveyed toward the registration roller pair 49. The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the secondary transfer nip as the belt moves endlessly. The registration roller pair 49 sends out the transfer paper sandwiched between the rollers at a timing at which the transfer paper can be brought into close contact with the four-color toner image at the secondary transfer nip. Thereby, in the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the transfer paper. Then, it is secondarily transferred onto the transfer paper and becomes a full color image on the white transfer paper. The transfer paper on which the full-color image is formed in this manner exits the secondary transfer nip as the paper transport belt 24 moves endlessly, and then is sent from the paper transport belt 24 to the fixing device 25.

  The fixing device 25 includes a belt unit that stretches the fixing belt 26 by two rollers and moves endlessly, and a pressure roller 27 that is pressed toward one roller of the belt unit. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the transfer paper received from the paper transport belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed from the pressure roller 27 has a heat source (not shown) inside, and heats the fixing belt 26 by the heat generated by the heat source. The heated fixing belt 26 heats the transfer paper sandwiched in the fixing nip. The full color image is fixed on the transfer paper by the influence of the heating and the nip pressure.

  The transfer paper subjected to the fixing process in the fixing device 25 is stacked on the stack portion 57 provided outside the left side plate in the drawing of the printer housing, or forms a toner image on the other surface. Any one of the transport modes to be returned to the secondary transfer nip is selected.

  When copying a document (not shown), for example, a bundle of sheet documents is set on the document table 30 of the automatic document feeder 400. However, when the original is a single-sided original that is closed in a main form, it is set on the contact glass 32. Prior to this setting, the automatic document feeder 400 is opened with respect to the copying machine main body, and the contact glass 32 of the scanner 300 is exposed. Thereafter, the single-bound original is pressed by the closed automatic document feeder 400. When a copy start switch (not shown) is pressed after the document is set in this way, the document reading operation by the scanner 300 starts. On the other hand, when a sheet document is set on the automatic document feeder 400, the automatic document feeder 400 automatically moves the sheet document to the contact glass 32 prior to this document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. Then, the reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, passes through the imaging lens 35, and then enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

  In parallel with such document reading operation, each device in each of the process cartridges 18Y, 18M, 18C, 18K, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 starts driving. Then, based on the image information constructed by the reading sensor 36, the optical writing unit (exposure device) 21 is driven and controlled, and Y, M, C, and K toner images on the respective photoreceptors 1Y, 1M, 1C, and 1K. Is formed. These toner images become four-color toner images superimposed and transferred on the intermediate transfer belt 110.

  Further, almost simultaneously with the start of the document reading operation, the paper feeding operation is started in the paper feeding device 200. In this paper feeding operation, one of the paper feeding rollers 42 is selectively rotated, and the transfer paper is sent out from one of the paper feeding cassettes 44 accommodated in the paper bank 43 in multiple stages. The fed transfer paper is separated one by one by the separation roller 45 and enters the paper feed path 46, and is then transported toward the secondary transfer nip by the transport roller pair 47. In some cases, paper feeding from the manual feed tray 51 is performed instead of such paper feeding from the paper feeding cassette 44. In this case, after the manual feed roller 50 is selectively rotated to feed the transfer paper on the manual feed tray 51, the separation roller 52 separates the transfer paper one by one and feeds it to the manual feed path 53 of the printer unit 100. Make paper.

  In the case of forming a multicolor image composed of two or more colors of toner, the copying machine 500 stretches the intermediate transfer belt 110 so that the upper stretched surface is almost horizontal, and all the upper stretched surface is placed on the upper stretched surface. Photoconductors 1Y, 1M, 1C, and 1K are brought into contact with each other. On the other hand, when forming a monochrome image consisting of only K toner, the intermediate transfer belt 110 is tilted to the lower left in the drawing by a mechanism (not shown) and the upper stretched surface is set to Y, M, C. The photoconductors 1Y, 1M, and 1C are separated. Of the four photoconductors 1Y, 1M, 1C, and 1K, only the K photoconductor 1K is rotated counterclockwise in the drawing to form only the K toner image. At this time, for Y, M, and C, not only the photosensitive member 1 but also the developing device 4 is stopped, and each member of the photosensitive member 1 and the developing device 4 and the toner and magnetic carrier (hereinafter referred to as the developing device 4). Unnecessary consumption of a two-component developer (hereinafter referred to as “developer”).

  The copier 500 includes a control unit as a control unit (not shown) configured by a CPU that controls each device in the copier 500, an operation display unit (not illustrated) configured by a liquid crystal display, various key buttons, and the like. It has. The operator sends a command to the control unit by a key input operation on the operation display unit, so that the single-sided printing mode, which is a mode for forming an image only on one side of the transfer paper, can be selected from, for example, three modes. One can be selected. The three single-sided printing modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

  FIG. 2 is an enlarged configuration diagram showing the developing device 4 and the photoreceptor 1 provided in the process cartridges 18Y, 18M, 18C, and 18K, respectively, in the copying machine according to the present embodiment. Since the four process cartridges 18Y, 18M, 18C, and 18K have substantially the same configuration except that the colors of the toners to be handled are different from each other, Y, M, C, and the like denoted by “4” in FIG. The subscript K is omitted.

  As shown in FIG. 2, the surface of the photosensitive member 1 is charged by a charging device (not shown) while rotating in the direction of arrow G in the drawing. An electrostatic latent image is formed on the surface of the charged photoreceptor 1 by laser light emitted from an optical writing unit (exposure device) (not shown), and toner is supplied to the electrostatic latent image from the developing device 4. A toner image is formed.

  The developing device 4 stores a developer containing toner and a carrier, and supplies the toner to the latent image on the surface of the photosensitive member 1 while developing the developer in the direction of arrow I in the drawing as a developer carrying member. The developing roller 5 is provided. The developing roller 5 includes a developing sleeve 81 as a developer support means that can rotate, and includes a magnet roller 82 as a first magnetic field generating means that is composed of a plurality of magnetic poles and that can rotate in the direction of arrow A in the figure. .

The developing sleeve 81 is made of a nonmagnetic and conductive material such as aluminum, austenitic stainless steel, or magnesium. The surface of the developing sleeve 81 may be smooth, but in a high speed machine, any of the following roughening treatments / processings (A) to (C) may be performed to suppress developer slip.
(A) Groove extrusion processing such as V-groove or U-groove, machining of various concave shapes or laser processing or edging processing (B) Blasting processing (C) Thermal spraying processing of metal or ceramic

  The magnet roller 82 uses Sr ferrite or Ba ferrite as magnet powder, and a PA (polyamide) material such as 6PA or 12PA as a polymer compound, EEA (ethylene / ethyl copolymer) or EVA (ethylene / vinyl copolymer). ) And the like, chlorine-based materials such as CPE (chlorinated polyethylene), and rubber materials such as NBR. The magnet roller 82 has a plurality of magnetic poles (in the example shown, five magnetic poles P14, P15, P11, P12, P13) by magnetization. The developer on the developing sleeve 81 is conveyed in the order of P14 (N) → P15 (S) → P11 (N) → P12 (S) → P13 (N). The symbol in parentheses indicates the polarity of the magnetic pole. However, since the magnetic pole P13 and the magnetic pole P14 have the same polarity, a repulsive magnetic field is generated, and the developer falls at a position past the position facing the magnetic pole P13. A magnetic pole P11, which is a developing pole, faces the photoreceptor 1 and has a function of supplying toner to the latent image on the surface of the photoreceptor 1 and holding the carrier on the developing roller 5 to prevent carrier adhesion. It is possible to reduce carrier adhesion by making the magnetic pole P11 a high magnetic material such as a rare earth magnet. A magnetic pole P12 as a magnetic spike generating magnetic pole, which is one of the plurality of magnetic poles, is disposed at a position facing a toner collecting roller 13 (to be described later) as a toner collecting means (toner collecting member). The toner collecting roller 13 is a roller that prevents scattering of floating toner, and is also referred to as a toner scattering prevention roller.

  Further, the developing device 4 supplies the developer to the developing roller 5 along the axial direction of the developing roller 5 along the axial direction of the developing roller 5 (hereinafter, for the sake of convenience, “back side in the drawing” or “back in FIG. 2”). A supply screw 8 serving as a supply conveyance member that conveys the developer toward the side. A doctor blade 12 serving as a developer regulating means for regulating the developer supplied to the developing roller 5 to a thickness suitable for development is provided downstream of the developing roller 5 facing the supply screw 8 in the developer transport direction. I have. Further, on the downstream side in the developer transport direction with respect to the developing region that is the portion of the developing roller 5 facing the photoreceptor 1, the developer that collects the developed developer that has passed through the developing region and separated from the surface of the developing roller 5 is collected. The conveyance path 7 faces the developing roller 5. The collection conveyance path 7 is a collection conveyance member that conveys the collected developer collected in the same direction as the supply screw 8 along the axial direction of the developing roller 5. I have. A supply conveyance path 9 provided with a supply screw 8 is arranged in parallel above the developing roller 5, and a collection conveyance path 7 provided with a collection screw 6 is arranged in parallel below the development roller 5.

  Further, the developing device 4 is provided with an agitation transport path 10 in parallel with the supply transport path 9 and the recovery transport path 7. The agitation conveyance path 10 is inclined so as to be substantially the same height as the collection conveyance path 7 on the back side and the supply conveyance path 9 on the front side. In addition, the agitating and conveying path 10 is a direction opposite to the supply screw 8 while stirring the developer along the axial direction of the developing roller 5, that is, the front side of the sheet of FIG. A stirring / conveying member that conveys in the direction of (sometimes referred to as). In the present embodiment, the stirring and conveying member includes a spiral stirring screw 11 arranged in an inclined manner in the axial direction. The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition wall. The supply conveyance path 9 and the agitation conveyance path 10 of the first partition wall 133 have an opening on the front side in the figure, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. Further, the supply conveyance path 9 and the collection conveyance path 7 are partitioned by a second partition wall 134. The supply conveyance path 9 and the collection conveyance path 7 of the second partition wall 134 have an opening on the back side in the drawing, and the supply conveyance path 9 and the collection conveyance path 7 communicate with each other. In addition, the two developer conveyance paths of the agitation conveyance path 10 and the recovery conveyance path 7 are partitioned by a third partition wall 135 as a partition member. The third partition wall 135 has an opening on the back side in the figure, and the stirring conveyance path 10 and the collection conveyance path 7 communicate with each other.

  The supply screw 8, the recovery screw 6 and the stirring screw 11, which are developer conveying members, are made of resin or metal screws. The diameters of the screws are 26 (mm) for the supply screw 8 and the recovery screw 6, and the stirring screw 11 is φ30 (mm). The supply screw 8 is a double winding with a screw pitch of 54 (mm), the recovery screw 6 is a double winding with a screw pitch of 36 (mm), and the stirring screw 11 has a screw pitch of 54 (mm). It is a double roll. The number of rotations of each screw is set to about 600 (rpm).

  The developer carried on the developing roller 5 is thinned by a doctor blade 12 made of stainless steel, and then transported to a developing region that is a portion facing the photosensitive member 1, so that the latent image on the photosensitive member 1 is developed. Done. The diameter of the developing roller 5 is φ40 (mm), and the gaps between the developing roller 5 and the doctor blade 12 and the photoreceptor 1 are about 0.3 (mm), respectively.

  The developer after development is collected in the collection conveyance path 7, conveyed to the back side in FIG. 2, and developed to the agitation conveyance path 10 at the opening of the third partition wall 135 provided in the non-image area portion. The agent is transferred. In addition, in the vicinity of the opening of the second partition wall 134 on the downstream side in the developer conveyance direction in the supply conveyance path 9, on the upper side of the supply conveyance path 9, as shown in FIG. Toner 9 is supplied.

Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 3 is a partial perspective view of the developing device 4 for explaining the flow of the developer in the developer transport path. Each arrow in the figure indicates the moving direction of the developer. In FIG. 3, the developer is supplied in contact with the developing roller 5 while moving in the supply conveyance path 9 that receives the supply of the developer from the agitation conveyance path 10. The surplus developer that has moved to the downstream end in the transport direction of the supply transport path 9 without being supplied to the developing roller 5 is supplied to the recovery transport path 7 from the surplus opening of the second partition wall 134 (arrow in FIG. 3). E).

  On the other hand, the developer supplied to the developing roller 5 is used for development in the developing region, and then separated from the developing roller 5 and separated from the developing roller 5 and is delivered to the collection conveyance path 7. The collected developer that has been transferred from the developing roller 5 to the collection conveyance path 7 and conveyed to the downstream end in the conveyance direction of the collection conveyance path 7 by the collection screw 6 passes through the collection opening of the third partition wall 135 to the stirring conveyance path 10. Supplied (arrow F in FIG. 3).

  In the agitating / conveying path 10, the excess developer supplied from the supply / conveying path 9, the collected developer collected in the collecting / conveying path 7, and the toner replenished from a toner replenishing port 95 (see FIG. 4) described later (FIG. 3 arrow t) is stirred. The agitated developer is conveyed downstream in the conveying direction of the agitating screw 11 and upstream in the conveying direction of the supply screw 8, and is supplied to the supply conveying path 9 from the supply opening of the first partition wall 133. (Arrow D in FIG. 3).

  A toner concentration sensor (not shown) composed of a magnetic permeability sensor is provided below the agitation transport path 10, and a toner supply control device (not shown) is operated based on the output of the toner concentration sensor. Toner is supplied from the toner container.

  In the developing device 4 shown in FIG. 3, a supply conveyance path 9 and a collection conveyance path 7 are provided, and developer supply and collection are performed in different developer conveyance paths, so that developed developer is supplied to the supply conveyance path 9. There is no contamination. For this reason, it is possible to suppress a decrease in the toner concentration of the developer supplied to the developing roller 5 toward the downstream side of the supply conveyance path 9 in the conveyance direction. Further, since the recovery conveyance path 7 and the agitation conveyance path 10 are provided and the developer recovery and agitation are performed in different developer conveyance paths, the developed developer does not fall during the agitation. Thereby, since the sufficiently stirred developer is supplied to the supply conveyance path 9, it is possible to suppress the developer supplied to the supply conveyance path 9 from being insufficiently stirred. In this way, the toner density of the developer in the supply conveyance path 9 can be suppressed from decreasing, and the developer in the supply conveyance path 9 can be prevented from being insufficiently stirred, so the image density during development can be reduced. Can be constant.

FIG. 4 is an external perspective view for explaining the toner replenishment position of the developing device 4.
As shown in FIG. 4, the toner replenishing port 95 for replenishing toner is provided above the downstream end in the transport direction of the supply transport path 9 including the supply screw 8. The toner replenishing port 95 is located above the surplus opening (arrow E in FIG. 3) of the second partition wall 134, so that the toner easily mixes with the surplus developer and the collected developer, and replenishment is performed at this position. Thus, the developer can be more efficiently stirred.

  Next, the configuration of the developing roller 5 and the toner collecting roller 13 in the developing device of the copying machine having the above-described configuration and the surroundings will be described.

  FIG. 5 is a partially enlarged view of a main part where the developing roller 5 and the toner collecting roller 13 are opposed to each other. In FIG. 5, a developing roller 5 includes a developing sleeve 81 as a cylindrical developer supporting means for carrying the developer, and a first magnetic field generating means that is contained in the developing sleeve 81 and attracts the developer by magnetic force. And a magnet roller 82. The magnet roller 82 of the developing roller 5 has a plurality of magnetic poles (in the present embodiment, five magnetic poles P14, P15, P11, P12, P13 as shown in FIG. 2) as shown in FIG. Yes. At least one of the plurality of magnetic poles (in this embodiment, the magnetic pole P12) is provided so as to form a magnetic field that causes the developer to spike at a position facing the toner recovery roller 13.

  The toner collecting roller 13 is provided downstream of the developing region where the developing roller 5 and the photosensitive member 1 face each other in the surface moving direction of the photosensitive member 1 and is rotatable to collect the floating toner floating in the developing device 4. Is a roller. The toner collecting roller 13 is disposed so as not to contact either the surface of the developing roller 5 or the surface of the photosensitive member 1 and to contact the developer spiked by the magnetic field generated by the at least one magnetic pole P12. Has been.

The toner collecting roller 13 includes a rotatable hollow sleeve 90 and flanges (not shown) press-fitted to both ends of the hollow sleeve 90. The hollow sleeve 90 is made of a nonmagnetic and conductive material such as aluminum, austenitic stainless steel, or magnesium. The surface of the hollow sleeve 90 may be smooth, but any of the following roughening treatments / processings (A) to (C) may be performed to prevent re-scattering of the adhered toner.
(A) Groove extrusion processing such as V-groove or U-groove, machining of various concave shapes or laser processing or edging processing (B) Blasting processing (C) Thermal spraying processing of metal or ceramic

  For the processing of (A) above, the depth of the groove or recess is about 0.05 (mm) to 0.5 (mm), and the shape, number, etc. thereof can be set, for example, in the same manner as in the known art. Is possible. About the process of said (B), the roughness has the preferable range of Rz7 (micrometer)-Rz50 (micrometer). This roughness range is a range that can be manufactured in the above (B), and is a preferable range that can prevent re-scattering of toner. About the process of said (C), the roughness has the preferable range of Rz40 (micrometer)-Rz90 (micrometer). This roughness range is a range that can be manufactured in the above (C), and is a preferable range that can prevent re-scattering of toner.

  In this embodiment, since the diameter of the toner recovery roller 13 is relatively large, φ20 (mm), a hollow sleeve is used for cost reduction and mass reduction. If the toner collection roller 13 has a relatively small diameter of approximately φ10 (mm) or less, the solid shaft may be more advantageous in terms of cost and mass.

  Further, it is preferable that the gap between the surface of the photosensitive member 1 and the surface of the toner collecting roller 13 is smaller than the gap between the surface of the developing roller 5 and the surface of the toner collecting roller 13. For example, the gap a between the toner collection roller 13 and the photosensitive member 1 is set to 0.5 (mm), and the gap b between the toner collection roller 13 and the developing roller 5 is set to 2 (mm).

  Further, as shown in FIG. 5, a casing 96 is provided on the opposite side of the toner collecting roller 13 from the developing roller 5 (below the toner collecting roller 13 in FIG. 5). The gap between the toner recovery roller 13 and the casing 96 is set to 1.5 (mm), for example. The casing 96 is provided with a shield magnet 91 as second magnetic field generation means (magnetic field generation means for preventing developer leakage, magnetic shield generation means). The shield magnet 91 is provided so as to face the surface of the toner collection roller 13 in a non-contact manner, and generates a magnetic field that prevents the developer from moving between the toner collection roller 13 and the casing 96 in a direction that leaks out of the developing device 4. generate. As the shield magnet 91, a rubber magnet is used for cost reduction and improvement of the pasting workability. However, the shield magnet 91 is not limited to this, and a block magnet may be used.

Next, a method for driving the toner collection roller 13 will be described.
FIG. 6 is a schematic configuration diagram illustrating a configuration example of the driving unit of the toner collection roller 13. In FIG. 6, the end of the recovery screw 6 on the front side of the developing device 4 is provided with an eccentric cam 97. The eccentric cam 97 is fitted into the elongated hole of the cam follower 98 in a rotatable state. A one-way clutch 99 is press-fitted into the opposite end of the cam follower 98, and a drive shaft of the toner collecting roller 13 is inserted into the inner diameter portion of the one-way clutch 99.

  In FIG. 6, when the eccentric cam 97 rotates in the P direction by the rotation of the recovery screw 6, the cam follower 98 swings in the Q direction and the R direction. The one-way clutch 99 is locked only during the Q-direction operation and is idled during the R-direction operation, so that the toner recovery roller 13 is intermittently driven in the J-direction. By setting the swing angle of the cam follower 98 to, for example, 7.2 (°), when the recovery screw 6 rotates 50 times, the toner recovery roller 13 rotates 360 (°), that is, once. Since the collecting screw 6 rotates at about 600 (rpm), the toner collecting roller 13 rotates intermittently at an extremely low speed of about 12 (rpm).

  The drive unit shown in FIG. 6 can obtain a large reduction ratio with a simple configuration. However, the drive system of the toner collection roller 13 is not limited to this configuration, and is reduced by a plurality of gears and timing belts, and a small dedicated motor. It is also possible to select a method such as installation.

  In the developing device 4 configured as described above, the developing sleeve 81 and the hollow sleeve 90 are rotated in the I and J directions, that is, in the same direction in FIG. That is, the developing sleeve 81 and the hollow sleeve 90 are rotated so that the surface of the developing sleeve 81 and the surface of the hollow sleeve 90 move in directions opposite to each other at a position where the developing roller 5 and the toner collecting roller 13 face each other. ing. Hereinafter, the movement of the developer and the recovery operation of the carrier at this time will be described with reference to FIG.

  In FIG. 5, the developer that has supplied toner to the photoreceptor 1 near the magnetic pole P11 on the developing roller 5 has fallen due to centrifugal force or gravity after passing through the magnetic pole P12 (arrow K). However, after passing through the magnetic pole P13, the rest falls (arrow L). Part of the dropped developer tends to leak from the gap between the toner collection roller 13 and the casing 96 (arrow M). At this time, the developer that is about to leak from the gap between the toner collection roller 13 and the casing 96 is blocked by the magnetic shield by the shield magnet 91, that is, by the magnetic head of the carrier formed by the magnetic force of the shield magnet 91. Leakage is prevented.

On the other hand, in the space O surrounded by the photosensitive member 1, the developing roller 5, and the toner collecting roller 13, toner cloud is generated violently due to the movement of the developer and the rise and fall. Therefore, a negative pressure is generated by rubbing the spikes caused by the magnetic pole P12 against the toner collecting roller 13, and the toner cloud is sucked into the developing device 4 together with the developer. Further, the gap b (2 mm) between the toner collecting roller 13 and the developing roller 5 is made larger than the gap a (0.5 mm) between the toner collecting roller 13 and the photosensitive member 1 (a <b). Thus, the difference in flow path resistance is made, so that the toner cloud is difficult to flow out of the developing device 4 and easily flows into the developing device 4. A part of the toner cloud adheres to the surface of the toner collecting roller 13 (arrow P), but when the toner collecting roller 13 rotates and reaches the vicinity of the opposite portion of the developing roller 5, the developer is rubbed by the magnetic brush of the magnetic pole P12. It is taken in and collected into the developing device 4.

  The magnetic spikes formed by the shield magnet 91 and the magnetic pole P12 are extremely soft because they are a continuum of magnetic carrier particles, and even if they are rubbed against the toner recovery roller 13, problems such as heat generation do not occur. Further, as described above, the toner collecting roller 13 is intermittently rotated at an extremely low speed to prevent the toner adhering to the toner collecting roller 13 from re-scattering, and further, the surface is roughened as described above. May be applied.

The toner collection roller 13 can be rotated in either direction. However, as described in the above embodiment, since the relative speed due to the rubbing of the magnetic spikes increases when the developing roller 5 and the toner recovery roller 13 face each other in the opposite direction, they adhere to the toner recovery roller 13. High toner removal effect. As described above, the shield magnet 91 is disposed in the vicinity of the toner collecting roller 13 to generate a magnetic shield, thereby preventing the developer from leaking. Further, since the toner adhering to the surface can be removed by sliding the magnetic brush of the developing roller 5 on the toner collecting roller 13, a scraper or foaming material that contacts the surface and scrapes the toner as in the prior art. Can be abolished.

  There is a sufficient effect of preventing toner scattering by the method described above. However, there is a slight outflow of toner from the gap between the toner collecting roller 13 and the photosensitive member 1, and there is a possibility that the inside of the apparatus is contaminated when used for a long time. For this reason, in the copying machine 500 according to the present embodiment, toner scattering is further reduced by the following method.

FIG. 7 is a schematic configuration diagram for explaining toner removal from the toner collection roller 13.
In FIG. 7, the photosensitive member 1 is charged to about −600 (V) by a charging device (not shown) (background portion), and discharged to about −100 (V) by an optical writing unit (exposure device) (not shown). Part). Further, the process in the copying machine 500 of the present embodiment is a negative-positive process using a developer in which toner is negatively charged and carrier is positively charged. In this negative-positive process, a developing bias power supply 900 as a developing bias applying means (electric field forming means) applies about −500 (V) as a developing bias to the developing sleeve 81 of the developing roller 5. Further, a toner recovery bias is applied by a toner recovery bias power source 910 as a toner recovery bias application unit (electric field forming unit) so that the potential of the hollow sleeve 90 of the toner recovery roller 13 is about −700 (V). . In this way, a predetermined electric field is formed by applying a predetermined bias to each of the developing sleeve 81 of the developing roller 5 and the hollow sleeve 90 of the toner collecting roller 13. That is, the potential of the toner collecting roller 13 is set lower than the surface potential of the photosensitive member 1 and the potential of the developing sleeve 81.

  In FIG. 7, the large particles are the positive polarity carrier C and the small particles are the negative polarity toner T. The potential difference of the hollow sleeve 90 viewed from the photoreceptor 1 is at least −100 (V). As a result, the positive polarity carrier C has an electrostatic force toward the hollow sleeve 90, but the negative polarity toner T has an electrostatic force toward the photosensitive member 1, so that the negative polarity toner T is not attracted to the hollow sleeve 90. . However, the floating toner floating in the developing device 4 may adhere to the hollow sleeve 90, although it is not aggressive. However, the potential of the developing sleeve 81 based on the potential of the hollow sleeve 90 is +200 (V). The toner T adhering to the hollow sleeve 90 is conveyed to a portion facing the developing sleeve 81 by the rotation of the hollow sleeve 90. The toner T on the hollow sleeve 90 conveyed to the portion facing the developing sleeve 81 is rubbed with a developer 83 (hereinafter referred to as “magnetic ear”) that is spiked on the developing sleeve 81. Simultaneously with the rubbing, the toner T on the hollow sleeve 90 is moved toward and adsorbed toward the developing sleeve 81 by an electric field formed by a potential difference (+200 (V)) with the developing sleeve 81. The developer on the developing sleeve 81 is taken in. Thereby, toner contamination on the surface of the toner collection roller 13 can be prevented, and the floating toner collection function by the toner collection roller 13 can be maintained.

  In the above-described embodiment, the negative positive process using the negative toner is used, but the same effect can be obtained by appropriately selecting the potential polarity in the positive positive process using the positive toner.

  The inventor has conducted extensive experiments on the presence or absence of heat generation due to toner scattering and friction using the copying machine 500 according to the present embodiment. Table 1 shows the effects of the respective configurations and evaluation results for the comparative example and Examples 1-4.

  In the comparative example in Table 1, as shown in the prior art in FIG. 8, the scraper S is in contact with the toner recovery roller 13 in order to prevent the developer from leaking out of the developing device. There's a problem. Further, when the scraper S is worn or wavy over time, the toner collecting roller 13 may be streaked.

  In Example 1, since the leakage of the developer was prevented by the shield magnetic field by the shield magnet 91, the scraper could be abolished and heat generation disappeared. However, since the toner collecting roller 13 has no function of removing the toner, the toner collecting roller 13 is contaminated.

  In Example 2, since the magnetic spikes by the magnetic pole P12 were rubbed against the toner collection roller 13, the contamination of the toner collection roller 13 was reduced.

  In Example 3, since the gap b (2 mm) between the toner collection roller 13 and the developing roller 5 is larger than the gap a (0.5 mm) between the toner collection roller 13 and the photosensitive member 1 (a <b), Toner scattering to the outside of the developing device was further reduced.

  In Example 4, a potential difference was provided between the developing roller 5 and the toner collecting roller 13. Since the potential difference is set to a polarity at which the toner attached to the toner collection roller 13 is transferred to the development roller 5 at a position where the development roller 5 and the toner collection roller 13 face each other, the scattering of the toner to the outside of the developing device is further reduced. The contamination of the toner collecting roller 13 was further reduced.

In addition, as a developer used in this embodiment, a developer having the following configuration can be used.
The toner used in this embodiment contains at least a binder resin and a colorant, and if necessary, a release agent, a charge control agent, and other components. In addition to the above-mentioned additives, a fluidity improver and other components are added as necessary. For these materials, all known materials are possible. Examples of the binder resin include styrene, parachlorostyrene, vinyl toluene, vinyl chloride, vinyl acetate, vinyl propionate, methyl (meth) acrylate, ethyl (meth) tacrylate, propyl (meth) acrylate, (meth ) N-butyl acrylate, isobutyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) Hydroxypropyl acrylate, 2-chloroethyl (meth) acrylate, (meth) acrylonitrile acid, (meth) acrylamide, (meth) acrylic acid, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether. Examples include a weight body of monomers such as vinyl methyl ketone, N-vinyl pyrrolidone, N-vinyl pyridine and butadiene, a copolymer composed of two or more of these monomers, or a mixture thereof. In addition, polyester resin, polyol resin, polyurethane resin, polyamide resin, epoxy resin, rosin, modified rosin, terbene resin, phenol resin, hydrogenated petroleum resin, ionomer resin, silicone resin, ketone resin, xylene resin, etc. alone or in combination Can be used.

  As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, Yellow lead, Titanium yellow, Polyazo yellow, Oil yellow, Hansa yellow (GR, A, RN, R), Pigment yellow L, Benzidine yellow (G, GR), Permanent yellow (NCG), Vulcan fast yellow (5G, R) ), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Se Red, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake , Thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone red, Riazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalo Cyanine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The amount used is generally 0.1 to 50 parts by mass with respect to 100 parts by mass of the binder resin.

  Examples of the charge control agent include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts). .), Alkylamide, phosphorus simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, the range of 2-5 mass parts is good. If the amount is less than 0.1 parts by mass, the toner is insufficiently charged and is not practical. When the amount exceeds 10 parts by mass, the chargeability of the toner is too high, and the electrostatic attraction force with the carrier increases, leading to a decrease in developer fluidity and a decrease in image density.

Examples of release agents include low molecular weight polyolefin waxes such as low molecular weight polyethylene and low molecular weight polypropylene, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, beeswax, carnauba wax, candelilla wax, rice wax, and montan wax. Natural waxes such as paraffin wax, petroleum wax such as microcrystalline wax, higher fatty acids such as stearic acid, palmitic acid, myristic acid, metal salts of higher fatty acids, higher fatty acid amides, and various modified waxes thereof. Can be mentioned.

  These may be used alone or in combination of two or more, but it is preferable to use those having a melting point in the range of 70 to 125 (° C). By setting the melting point to 70 (° C) or higher, it is possible to obtain a toner having excellent transferability and durability. By setting the melting point to 125 (° C) or lower, the toner is quickly melted at the time of fixing, and reliable release. The effect can be demonstrated. The amount of these release agents used is preferably 1 to 15 (% by mass) based on the toner. If it is less than 1 (mass%), the effect of preventing offset is insufficient, and if it is 15 (mass%) or more, the transferability and durability are lowered.

As an additive (external additive), fine particles having a volume average particle size of 50 to 500 (nm) and a bulk density of 0.3 (g / cm ³ ) or more are added. The amount of external addition is preferably 0.2 to 3 (% by mass) with respect to the toner base. If the amount is less than this range, the effect of forming an appropriate gap between the toners or between the toner and the others is not exhibited. On the other hand, when the amount is large, fluidity is inhibited, or the amount of desorption increases, so that aggregates of external additives are formed, and image quality is deteriorated. In addition to the above-mentioned additives, additives outside this range can be added, and it is preferable to add fine particles having a small volume average particle diameter for the purpose of improving fluidity.

In the additive in the present embodiment, as the inorganic _{compound, SiO 2, TiO 2, Al} 2 O 3, MgO, CuO, ZnO, SnO 2, CeO 2, Fe 2 O 3, BaO, CaO, K 2 O, Examples include Na ₂ O, ZrO ₂ , CaO · SiO ₂ , K ₂ O (TiO ₂ ) n, Al ₂ O ₃ · 2SO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO _{3 and the} like. Of these, SiO ₂ , TiO ₂ , and Al ₂ O ₃ are preferable. In particular, these inorganic compounds may be hydrophobized with various coupling agents, hexamethyldisilazane, dimethyldichlorosilane, octyltrimethoxysilane, and the like. Further, the organic compound additive may be a thermoplastic resin or a thermosetting resin, for example, vinyl resin, polyurethane resin, epoxy resin, polyester resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin. , Urea resin, aniline resin, ionomer resin, polycarbonate resin and the like. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.

  Specific examples of vinyl resins include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid. -Acrylic ester copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, and the like.

  The additive (fine particles) in this embodiment is excellent as a toner for a developer in the developing device. That is, the contact area with the toner particles, the photoconductor drum, and the charge imparting member is very small and contacts evenly, so the effect of reducing adhesion is great and effective in improving development / transfer efficiency. Furthermore, since it acts as a roller, it is buried in the toner particles even when cleaning the cleaning drum and the photosensitive drum under high stress (high load, high speed, etc.) without wearing or damaging the photosensitive drum. It is difficult to remove or return even after being buried a little, so that stable characteristics can be obtained over a long period of time. Further, the toner is moderately detached from the surface of the toner and accumulated at the tip of the cleaning blade, and the so-called dam effect has an effect of preventing a phenomenon that the toner passes from the blade.

  As a method for producing the toner in the present embodiment, a method obtained by melting and kneading a toner constituent material and then pulverizing and classifying is generally used as a conventional method, but is not limited to this method. A method is possible. As the polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, and the like are possible. Although different from the polymerization method, in addition to a dissolution suspension method, a polymer suspension method, etc., an extension reaction method or the like can be used. .

  Other than the conventional method is preferable in that the toner having the above-described particle size range and circularity can be easily obtained. Further, the circularity may be adjusted by subjecting the toner after pulverization and classification to heat treatment.

  The method for adding the additive in the present embodiment is not particularly limited, and a method in which the toner base particles and the additive are mechanically mixed and adhered using various known mixing devices, or a toner base in a liquid phase. There is a method in which particles and additives are uniformly dispersed with a surfactant or the like, and after an adhesion treatment, dried.

The particle size distribution of the toner described above can be measured by using a toner particle size distribution measuring apparatus by the Coulter counter method. Examples of these devices include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter).
The measurement method is described below.

  First, 0.1 to 5 (ml) of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 (ml) of the aqueous electrolytic solution. Here, the electrolytic solution is prepared by preparing about 1 (%) NaCl aqueous solution using primary sodium chloride, and for example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 (mg) of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the weight and number of toner particles or toner are determined by using the 100 (μm) aperture as the aperture by the above-described measuring apparatus. Measure and calculate weight distribution and number distribution. From the obtained distribution, the weight average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

  As a channel, it is less than 2.00-2.52 (micrometer); 2.52-3.17 (micrometer); 3.17-4.00 (micrometer); 4.00-5.04 (micrometer) Less than 5.04 to 6.35 (μm); 6.35 to less than 8.00 (μm); 8.00 to less than 10.08 (μm); 10.08 to less than 12.70 (μm); 12.70 to less than 16.00 (μm); 16.00 to less than 20.20 (μm); 20.20 to less than 25.40 (μm); 25.40 to less than 32.00 (μm); Using 13 channels of 00 to less than 40.30 (μm), particles having a particle size of 2.00 (μm) or more and less than 40.30 (μm) are targeted.

The circularity of the toner described above is a value obtained by the following equation (1).
Circularity = (perimeter of a circle having the same area as the projected area of the particle) / (perimeter of the projected image of the particle) (1)

  The circularity is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere. The more complicated the surface shape, the smaller the circularity.

  The circularity can be measured using, for example, a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics. As a specific measuring method, a surfactant, preferably an alkylbenzene sulfonate, is added in an amount of 0.1 to 0.5 (as a dispersant) in 100 to 150 (ml) of water from which impure solids have been previously removed. ml) and about 0.1 to 0.5 (g) of a measurement sample. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the concentration of the dispersion is set to 3000 to 10,000 (pieces / μl), and the shape of the toner is measured with the above-described apparatus.

Hereinafter, the carrier used in this embodiment will be described supplementarily.
The carrier used in the present embodiment is formed so that the weight average particle diameter is 20 to 60 (μm) (preferably 20 to 45 (μm)). This particle size range is also excellent as a carrier for the developer in the developing device. When the average particle diameter of the carrier is less than 20 (μm), the fine particles are increased in the distribution of the carrier particles, and the magnetization per particle may be lowered to cause carrier scattering. On the other hand, if the average particle diameter of the carrier exceeds 45 (μm), the carrier spikes during the development process become rough, and the uniformity of solid and halftone may be inferior (particularly, the average particle diameter is It becomes remarkable when it exceeds 60 (μm)). In addition, since the specific surface area is reduced, toner scattering may occur in a small particle size toner.

  The carrier is not particularly limited except for the particle diameter, and can be appropriately selected according to the purpose. However, a carrier having a core material and a resin layer covering the core material is preferable.

  There is no restriction | limiting in particular as a material of a core material, It can select suitably from well-known things. For example, the core material is preferably 50 to 90 (emu / g) manganese-strontium (Mn-Sr) material, manganese-magnesium (Mn-Mg) material, etc. Highly magnetized materials such as iron powder (100 (emu / g) or more) and magnetite (75 to 120 (emu / g)) are preferable. Also, copper-zinc (Cu-Zn) type (30 to 80 (emu / g)) or the like is advantageous in that it can weaken the contact with the photosensitive drum in which the toner is in a spiked state and is advantageous for high image quality. The weakly magnetized material is preferred. These may be used alone or in combination of two or more.

  The material for the resin layer of the carrier is not particularly limited and can be appropriately selected from known resins according to the purpose. Examples thereof include amino resins, polyvinyl resins, polystyrene resins, and halogenated olefin resins. Polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, fluoride Examples thereof include a copolymer of vinylidene and vinyl fluoride, a fluoroterpolymer such as a terpolymer of tetrafluoroethylene, vinylidene fluoride, and a non-fluorinated monomer, and a silicone resin. These may be used individually by 1 type and may use 2 or more types together.

  The resin layer may contain conductive powder or the like as necessary. Examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. The average particle diameter of these conductive powders is preferably 1 (μm) or less. When the average particle diameter exceeds 1 (μm), it may be difficult to control electric resistance.

  The carrier resin layer is prepared, for example, by dissolving the silicone resin in a solvent to prepare a coating solution, and then uniformly coating the coating solution on the surface of the core by a known coating method, drying, and baking. It can form by performing. Examples of the application method include a dipping method, a spray method, and a brush coating method.

  The amount of the resin layer in the carrier is preferably 0.01 to 5.0 (% by mass). If the amount of the resin layer is less than 0.01 (% by mass), a uniform resin layer may not be formed on the surface of the core material. If the amount exceeds 5.0 (% by mass), the resin layer Becomes too thick and granulation of carriers occurs, and uniform carrier particles may not be obtained.

  The developer (initial agent) stored in advance in the developing device is also a mixture of the above-described toner and carrier. There is no restriction | limiting in particular as content (carrier density | concentration) of the carrier in a developing agent, According to the objective, it can select suitably. For example, 90-98 (mass%) is preferable and 93-97 (mass%) is more preferable.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A developer carrying member such as a developing roller 5 having a plurality of magnetic poles that form a magnetic field on the surface of the developer carrying member including a toner and a magnetic carrier is configured to be movable. A developing device 4 that develops a latent image formed on the image carrier by conveying the developer carried on the image carrier to a development region facing the image carrier such as the photosensitive member 1, The developer carrying member includes a toner collecting member such as a rotatable toner collecting roller 13 provided on the downstream side of the image carrying member in the surface movement direction and collecting floating toner floating in the developing device. At least one of the magnetic poles is provided so as to form a magnetic field that causes the developer to rise at a position facing the toner collecting member, and the toner collecting member may be either a surface of the developer carrying member or a surface of the image carrying member. Also contact Are arranged to contact the developer was allowed to napping in the magnetic field due and the at least one magnetic pole so as not.
According to this, as described in the above embodiment, the rotatable toner collecting member is provided on the downstream side in the surface moving direction of the image carrier from the developing region. With this toner collecting member, the floating toner floating in the developing device can be collected, so that the floating toner can be prevented from scattering. Further, at least one of the plurality of magnetic poles of the developer carrying member is provided so as to form a magnetic field for causing the developer to spike at a position facing the toner collecting member. Further, the toner recovery member is disposed at a position in contact with the developer spiked by the magnetic field generated by the at least one magnetic pole. The spiked developer rubs the surface of the rotating toner collecting member, so that the collected toner attached to the surface of the toner collecting member can be removed. As a result, the toner contamination on the surface of the toner collecting member can be removed and the floating toner collecting function of the toner collecting member can be maintained, so that toner scattering can be more reliably prevented. In addition, since the toner collecting member is arranged so as not to contact either the surface of the developer carrier or the surface of the image carrier, frictional heat is generated by the contact of the surface of the developer carrier and the like. Therefore, toner melting due to the frictional heat can be avoided. Therefore, it is possible to reliably prevent the toner from scattering while avoiding melting of the toner.
(Aspect B)
In the aspect A, a developer seal member that closes the opening from the opening of the casing 96 of the developing device 4 so that the developer does not leak out of the developing device 4 is provided, and the developer seal member is a toner such as the toner collection roller 13 It is provided so as not to contact the surface of the recovery member.
According to this, as described in the above embodiment, since heat is not generated due to friction between the developer seal member and the surface of the toner recovery member, toner melting can be avoided more reliably.
(Aspect C)
In the above aspect A or B, at the position where the developer carrying member such as the developing roller 5 and the toner collecting member such as the toner collecting roller 13 face each other, the toner collecting member is rotated so that the surface moving directions are opposite to each other. Let
According to this, as described in the above embodiment, compared to the case where the toner collecting member is rotated so that the surface movement directions of the developer carrying member and the toner collecting member face each other at the same position. The relative movement speed of the developer spiked on the developer carrying member with respect to the surface of the toner collecting member is increased, and the developer spiked on the developer carrying member adheres to the surface of the toner collecting member. The function of removing toner can be enhanced.
(Aspect D)
In any one of the above aspects A to C, the toner attached to the surface of the toner collecting member is between the surface of the developer carrying member such as the developing roller 5 and the surface of the toner collecting member such as the toner collecting roller 13. Electric field generating means such as a developing bias power source 900 and a toner recovery bias power source 910 for generating an electric field in a direction to move to the carrier side are provided.
According to this, as described in the above embodiment, the toner attached to the surface of the toner recovery member is removed by the predetermined electric field formed between the surface of the developer carrying member and the surface of the toner recovery member. Since the toner can be electrostatically moved to the carrier side, toner removal from the surface of the toner recovery member can be promoted.
(Aspect E)
An image forming apparatus such as a copying machine 500 including an image carrier such as a photoreceptor 1 and a developing device 4 that develops a latent image formed on the image carrier, the surface of the image carrier and toner collection The gap with the surface of the member is smaller than the gap between the surface of the developer carrying member and the surface of the toner collecting member such as the toner collecting roller 13.
According to this, as described in the above embodiment, the flow path resistance generated in the gap between the image carrier and the toner recovery member is larger than the flow path resistance generated in the gap between the developer carrier and the toner recovery member. . Since the air flow tends to flow in the direction where the flow path resistance is small, as described above, by causing a difference in the flow path resistance, the floating toner in the developing device 4 is difficult to flow out of the developing device and flows into the developing device. This makes it easier to prevent the toner from scattering outside the developing device.
(Aspect F)
In the above aspect E, a toner recovery bias power source that generates an electric field in a direction in which the toner moves to the image carrier side between the surface of the image carrier such as the photoreceptor 1 and the surface of a toner recovery member such as the toner recovery roller 13. Electric field generating means such as 910 is provided.
According to this, as described in the above embodiment, the toner attached to the surface of the toner collection member is removed from the image carrier side by a predetermined electric field formed between the surface of the image carrier and the surface of the toner collection member. Therefore, the toner removal from the surface of the toner collecting member can be promoted.

DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Developing apparatus 5 Developing roller 13 Toner collection roller 18 Process cartridge 81 Developing sleeve 82 Magnet roller 83 Magnetic spike 90 Hollow sleeve 91 Shield magnet (Magnetic field generating means, magnetic shield generating means for preventing developer leakage)
96 Casing 500 Copying machine 900 Developing bias power source 910 Toner recovery bias power source P12 Magnetic pole (magnetic head generating magnetic pole)

JP 2006-91155 A

Claims (9)

A developer carrying body including a toner and a magnetic carrier and having a plurality of magnetic poles that form a magnetic field on the surface is supported, and is carried on the surface of the developer carrying body. A developing device that develops a latent image formed on an image carrier by conveying the developer to a development region facing the image carrier,
A rotatable toner collecting member provided downstream of the developing region in the surface moving direction of the image carrier and collecting floating toner floating in the developing device;
At least one of the plurality of magnetic poles of the developer carrying member is provided so as to form a magnetic field that causes the developer to spike at a position facing the toner collecting member,
The toner collecting member is disposed so as not to contact either the surface of the developer carrier or the surface of the image carrier and to contact the developer spiked by a magnetic field by the at least one magnetic pole. A developing device. The developing device according to claim 1.
Magnetic field generating means for generating a magnetic field for preventing the movement of the developer in a direction leaking out of the developing device from between the toner collecting member and the casing of the developing device faces the surface of the toner collecting member in a non-contact manner. A developing device provided in the apparatus. The developing device according to claim 1 or 2,
A developing device, wherein at a position where the developer carrying member and the toner collecting member are opposed to each other, the toner collecting member is rotated so that the surface moving directions are opposite to each other. In the developing device according to any one of claims 1 to 3,
An electric field generating unit is provided between the surface of the developer carrying member and the surface of the toner collecting member to generate an electric field in a direction in which the toner attached to the surface of the toner collecting member moves to the developer carrying member. A developing device. An image forming apparatus comprising: an image carrier; and a developing unit that develops a latent image formed on the image carrier,
An image forming apparatus using the developing device according to claim 1 as the developing unit. The image forming apparatus according to claim 5.
An image forming apparatus, wherein a gap between the surface of the image carrier and the surface of the toner collecting member is smaller than a gap between the surface of the developer carrier and the surface of the toner collecting member. The image forming apparatus according to claim 5 or 6,
An image forming apparatus comprising: an electric field generating unit configured to generate an electric field in a direction in which the toner moves to the image carrier side between the surface of the image carrier and the surface of the toner collecting member. The image forming apparatus according to claim 5,
An image forming apparatus comprising a process cartridge in which the developing device and the image carrier are accommodated.   A process cartridge in which the developing device according to claim 1 and an image carrier are accommodated.

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