JP2015194676A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that can prevent adhesion of a developer over time in a developing device.SOLUTION: A developing device includes developer conveyance members 53 and 54 that convey a developer and a conveyance path 57 of the developer that has been conveyed by the developer conveyance members, and at least the surfaces of the developer conveyance members 53 and 54 or the surface of the conveyance path 57 is (are) a surface 90 having a developer non-adhesion property. The surface 90 having a developer non-adhesion property reveals the developer non-adhesion property with a rugged shape of the surface 90. The surface 90 having a developer non-adhesion property has a surface roughness Ra larger than 25nm at a measurement length of 2 μm measured by a scanning probe microscope. The surface 90 having a developer non-adhesion property has a surface roughness Ra smaller than 5 μm measured by a contact surface roughness meter according to JIS B0601:'01.

Description

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

  In an image forming apparatus using electrophotographic technology such as a copying machine or a printer, a visible image is formed with a developer on an image carrier such as a photosensitive member or an intermediate transfer member, and the visible image is finally recorded on a recording medium. Since a developer of a visible image that is transferred onto the image carrier but cannot be transferred remains on the image carrier, a cleaning device is provided for collecting the remaining developer. Some image forming apparatuses are provided with a developer recovery conveyance path for returning the recovered developer recovered by the cleaning device to the developing device. In order to reduce the environmental load, the melting point of the developer is being lowered. However, it was caused by the temperature rise during operation of the device, leaving it in a high temperature and high humidity environment, or deterioration of the developer over time. There is a risk of the developer sticking in the developing device and the developer sticking in the developer collecting / conveying path. If the developer fixed in the developer collecting / conveying path is peeled off due to vibration or the like, it may be conveyed into the developing device and cause an abnormal image.

As a technique for suppressing the sticking of the developer, for example, Patent Document 1 discloses a technique in which a release agent is applied to the inner wall of a developer supply transport path for transporting a developer composed of a carrier and toner from a toner cartridge to a developing device. Has been. However, as a result of intensive studies by the present inventors, it has been found that even when a release agent is applied, fixing of the developer is not necessarily suppressed.
In Patent Document 2, switching means for switching whether the collected developer is recycled or discarded is provided, and the operation of the switching means is controlled. However, since the switching unit is not controlled when the power of the image forming apparatus is turned off, the image forming apparatus is fixed when vibration is caused by attaching / detaching the unit when the image forming apparatus is stopped or when an unexpected vibration is given by the user. It cannot be solved that the developer peels off.

The present invention has been made in view of the above problems, and an object thereof is to suppress the sticking of the developer in the developing device over time.
The present invention has been made in view of the above problems, and an object thereof is to suppress the sticking of the developer in the developer recovery transport path over time.

In order to achieve the above object, in the developing device having a developer in the case according to the present invention, the surface in contact with the developer in the case has the developer difficult adhesion property, and the surface having the developer difficult adhesion property is Further, the developer is difficult to adhere due to the uneven shape of the surface.
In the image forming apparatus according to the present invention, the developer remaining on the image carrier on which a visible image is formed by the developer supplied from the developing device is collected by the cleaning device, and the developer collected by the cleaning device is collected. A developer recovery section for returning the developer to the developing means, the surface in contact with the developer in the developer recovery section has a developer difficult adhesion property, and the surface having the developer difficult adhesion property is due to the uneven shape of the surface. It was set as the structure which expressed difficult adhesion.

According to the developing device of the present invention, the surface in contact with the developer in the case is a surface that expresses difficult developer adhesion due to the uneven shape of the surface, so that the developer in the developing device over time Can be suppressed.
According to the image forming apparatus provided with the developer recovery unit according to the present invention, the surface in contact with the developer in the developer recovery unit that returns the developer recovered by the cleaning device to the developing unit is formed by the uneven shape of the surface. By setting it as a surface that exhibits poor developer adhesion, sticking of the developer in the developer recovery section over time can be suppressed.

FIG. 2 is a schematic diagram for explaining a configuration of an embodiment of an image forming apparatus having a developing device and a process cartridge. The figure for demonstrating one Embodiment of a structure of a process cartridge. FIG. 3 is a diagram for explaining a schematic configuration of an embodiment of a developing device according to the present invention. FIG. 2 is a perspective view illustrating a main part of an embodiment of a developing device according to the present invention. The figure for demonstrating the planar view and front view of a developing device, and the circulation state of a developing agent. FIG. 6 is a diagram for explaining a developer circulation state in a collected developer conveyance chamber and a supply developer conveyance chamber in the developing device. (A) is a figure explaining the structure of the developing device which concerns on the 1st Embodiment of this invention, (b) is an enlarged view explaining the structure of the developer conveyance member to which 1st Embodiment was applied. (A) is an enlarged view for explaining a configuration of a developer conveying member to which the first modification of the first embodiment is applied, and (b) is a developer conveying member to which the second modification of the first embodiment is applied. FIG. (A) is a figure explaining the structure of the developing device which concerns on the modification 3 of 1st Embodiment, (b) is an enlarged view explaining the structure of the developer conveyance member to which this invention was applied in the modification 3. FIG. (A) is a figure explaining the structure of the developing device which concerns on the modification 4 of 1st Embodiment, (b) is an enlarged view explaining the structure of the developer conveyance member to which this invention was applied in the modification 4. FIG. FIG. 9 is an enlarged view showing a developer flow in a developing device according to a fourth modification of the first embodiment. FIG. 9 is an enlarged view for explaining the configuration of a developing device according to Modification 5 of the first embodiment and the configuration of a collection guide to which the present invention is applied. The enlarged view explaining the structure of the developing device which concerns on the modification 6 of 1st Embodiment, and the structure of the collection | recovery guide to which this invention was applied. FIG. 2 is a schematic diagram for explaining an embodiment of an image forming apparatus including a developer recovery unit. FIG. 3 is a schematic diagram illustrating a flow of a developer from a cleaning device to a developing device. The perspective view explaining the structure of a developer collection | recovery part. (A), (b) is an expansion perspective view explaining the structure of the 2nd Embodiment of this invention, and the flow of a developer. (A) is a schematic diagram showing a state in which new toner particles are on a smooth surface, (b) is a schematic diagram showing a state in which deteriorated toner is on a fine uneven surface, and (c) is a surface roughness Ra. Is a schematic diagram of 5 μm. The figure explaining the SPM observation result of a toner and various developers difficult adhesion surface. The figure which shows the relationship between the adhesive force of the toner and various developer hard-to-adhere surface before and after aging evaluation, and the surface roughness Ra measured by SPM.

Hereinafter, a plurality of embodiments and modifications for carrying out the present invention will be described with reference to the drawings.
In the first embodiment and its modification, members and portions having a developer difficult adhesion property are provided in the developing device. Such a developing device and an image forming apparatus using the developing device will be described sequentially. Although a plurality of developing devices will be described, in either case, the image forming apparatus can be detachably attached to the main body of the image forming apparatus or the process cartridge can be used as a part of the process cartridge. It is assumed that it can be attached to and detached from the forming apparatus main body. Further, as an image forming apparatus that detachably supports each developing device and process cartridge, only the one shown in FIG. 1 is illustrated, and the process cartridge and the developing device in each embodiment are compared with the image forming apparatus main body of FIG. It shall be removable. In the first embodiment and its modifications, descriptions of those having the same function will be omitted as appropriate in the latter modification.

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus including a process cartridge including a developing device according to the present invention. In FIG. 1, reference numeral 10 denotes an apparatus main body of a tandem type color copier as an image forming apparatus, 32 denotes a document reading section provided with a document transport section for transporting a document, and 30 denotes a stack of output images. A paper discharge tray, 26 is a paper feed unit for storing a recording medium P such as transfer paper, 27 is a paper feed roller for feeding the recording medium P stored in the paper feed unit one by one, and 28 is a recording medium P. A pair of registration rollers for adjusting the conveyance timing is shown.
Reference numerals 6Y, 6M, 6C, and 6Bk are image forming portions for the respective colors (yellow (Y), magenta (M), cyan (C), and black (Bk)), and 1Y, 1M, 1C, and 1BK are toners of the respective colors. Photosensitive drums 5Y, 5M, 5C, and 5Bk as image carriers on which images are formed are developing devices that develop electrostatic latent images formed on the photosensitive drums 1Y, 1M, 1C, and 1BK, 9Y, Reference numerals 9M, 9C, and 9Bk denote transfer bias rollers (primary transfer bias rollers) that transfer the toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1BK in an overlapping manner on the recording medium P.
Reference numeral 8 denotes an intermediate transfer unit provided with an intermediate transfer belt 8A as an intermediate transfer body onto which toner images of a plurality of colors are transferred, and 19 is for transferring a color toner image on the intermediate transfer belt 8A onto a recording medium P. A secondary transfer bias roller as a secondary transfer member, a fixing device 20 for fixing an unfixed image on the recording medium P, and a developing device 31 for toner (toner particles) of each color (yellow, cyan, magenta, black). A bottle container for storing toner bottles 31Y, 31M, 31C, and 31BK of each color supplied to 5Y, 5M, 5C, and 5Bk is shown.

  As shown in FIG. 1, an intermediate transfer unit 8 is disposed in the apparatus main body 10. The image forming units 6Y, 6M, 6C, and 6Bk corresponding to the respective colors (yellow (Y), magenta (M), cyan (C), and black (Bk)) face the intermediate transfer belt 8A of the intermediate transfer unit 8 from below. Are arranged side by side. The four image forming units 6Y, 6M, 6C, and 6Bk are different in toner colors (yellow (Y), magenta (M), cyan (C), and black (Bk)) used in the electrophotographic image forming process. Except for the above, the structure is almost the same, for example, as shown in FIG. In FIG. 2, the alphabets (Y, M, C, and K) for the image forming unit 6, the photosensitive drum 1, and the primary transfer bias roller 9 are omitted.

2 includes a photosensitive drum 1 as an image carrier, a charging unit 4 disposed around the photosensitive drum 1, a developing device 5 as a developing unit, a cleaning unit 2, and the like. (Only the developing device 5 is shown in FIG. 1). In the image forming unit 6, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1, and a desired toner image is formed on the photosensitive drum 1. .
The photosensitive drum 1, the charging unit 4, the developing unit (developing device) 5, and the cleaning unit 2 constituting the image forming unit 6 are provided in a process cartridge 40 that is a unit that can be accommodated together. Each of the process cartridges 40 is configured so as to be detachable from an image forming apparatus main body (hereinafter referred to as “apparatus main body”) 100. It can be exchanged. In FIG. 1, process cartridges 40Y, 40M, 40C, and 40K are used.
As described above, by using the process cartridge 40 that is detachably provided in the apparatus main body 100, workability at the time of performing maintenance of the image forming unit 6 is improved, replacement is facilitated, and recyclability is improved.

  Hereinafter, an operation during normal color image formation in the image forming apparatus shown in FIG. 1 will be described. The image forming units 6Y, 6M, 6C, and 6Bk for each color (yellow (Y), magenta (M), cyan (C), and black (Bk)) are performed on the photosensitive drums 1Y, 1M, 1C, and 1BK. The image forming process will be described with reference to FIG.

First, the document is transported from the document table by a transport roller of a document transport unit (not shown) and placed on the contact glass of the document reading unit 32. Then, the document reading unit 32 optically reads the image information of the document placed on the contact glass.
More specifically, although not shown, the document reading unit 32 scans an image of the document on the contact glass while irradiating light emitted from an illumination lamp. Then, the light reflected from the original is imaged on the color sensor via the mirror group and the lens. The color image information of the original is read for each color separation light of RGB (red, green, blue) by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.
Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to an exposure unit (not shown) including, for example, a laser beam scanning optical writing device. Then, laser light L (FIG. 2) based on the image information of each color is emitted from the exposure unit toward the corresponding photosensitive drums 1Y, 1M, 1C, and 1BK.

  On the other hand, the four photosensitive drums 1Y, 1M, 1C, and 1BK rotate in the clockwise direction in FIG. First, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1BK are uniformly charged at a portion facing the charging unit 4 (see FIG. 2) (charging process). Thus, a charged potential is formed on the photosensitive drums 1Y, 1M, 1C, and 1BK. Thereafter, the charged photosensitive drums 1Y, 1M, 1C, and 1BK surfaces reach the irradiation position of laser light L emitted from an exposure unit (not shown), and an electrostatic latent image is formed by exposure scanning at this position. (Exposure process).

More specifically, in the exposure unit, laser light L corresponding to the image signal is emitted from four light sources corresponding to each color. Each laser beam L passes through a different optical path for each color component of yellow, magenta, cyan, and black.
The laser beam L corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 1Y from the left side of the paper. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 1Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 1Y charged by the charging unit 4.
Similarly, the laser beam L corresponding to the magenta component is irradiated onto the surface of the second photosensitive drum 1M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed.
The cyan component laser beam L is applied to the surface of the third photosensitive drum 1C from the left side of the paper, and an electrostatic latent image of the cyan component is formed.
The black component laser beam L is applied to the surface of the fourth photosensitive drum 1BK from the left side of the drawing, and an electrostatic latent image of the black component is formed.

  Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1BK on which the electrostatic latent images of the respective colors are formed reach positions facing the developing devices 5Y, 5M, 5C, and 5Bk of the developing unit, respectively. Then, the respective color toners are supplied from the developing devices 5Y, 5M, 5C, and 5Bk onto the photosensitive drums 1Y, 1M, 1C, and 1BK, and the latent images on the photosensitive drums 1Y, 1M, 1C, and 1BK are developed. (Development process).

  Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1BK after the development process reach the facing portions of the intermediate transfer belt 8A, respectively. Here, primary transfer bias rollers 9Y, 9M, 9C, and 9Bk are installed at the opposing portions so as to contact the inner peripheral surface of the intermediate transfer belt 8A. Then, the toner images of the respective colors formed on the photosensitive drums 1Y, 1M, 1C, and 1BK are sequentially superimposed and transferred onto the intermediate transfer belt 8A at the positions of the primary transfer bias rollers 9Y, 9M, 9C, and 9Bk. (Primary transfer process). At this time, a small amount of untransferred toner remains on the photosensitive drum 1.

  Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1BK after the transfer process reach positions facing the cleaning unit 2 (see FIG. 2), respectively. Then, the untransferred toner remaining on the photosensitive drums 1Y, 1M, 1C, and 1BK is collected by the cleaning blade 2a of the cleaning unit 2 (cleaning process). Thereafter, the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1BK reach a position facing a neutralization unit (not shown), and residual potentials on the photosensitive drums 1Y, 1M, 1C, and 1BK are removed at this position. . Thus, a series of image forming processes on the photosensitive drums 1Y, 1M, 1C, and 1BK is completed.

  The image forming process described above is performed by each of the four image forming units 6Y, 6M, 6C, and 6BK. That is, referring to FIG. 1, laser light L based on image information is emitted from the exposure unit disposed below the image forming unit onto the photosensitive drums of the image forming units 6Y, 6M, 6C, and 6BK. Irradiated towards. Specifically, the exposure unit emits laser light L from a light source and irradiates the photosensitive drum through a plurality of optical elements while scanning the laser light L with a polygon mirror that is rotationally driven. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the development process described above are transferred onto the intermediate transfer belt 8A in an overlapping manner. Thus, a color image is formed on the intermediate transfer belt 8A.

  The four primary transfer bias rollers 9Y, 9M, 9C, and 9K respectively sandwich the intermediate transfer belt 8A with the photosensitive drums 1Y, 1M, 1C, and 1K to form primary transfer nips. A transfer bias having a polarity opposite to the polarity of the toner is applied to the primary transfer bias rollers 9Y, 9M, 9C, and 9K. The intermediate transfer belt 8A travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9K. Thus, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred while being superimposed on the intermediate transfer belt 8A.

  Thereafter, the intermediate transfer belt 8 </ b> A on which the toner images of the respective colors are transferred in an overlapping manner reaches a position facing the secondary transfer roller 19. At this position, the secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8A between the secondary transfer roller 19 and forms a secondary transfer nip. The color toner image formed on the intermediate transfer belt 8A is transferred onto a recording medium P such as transfer paper conveyed to the secondary transfer nip position. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 8A. Untransferred toner remaining on the intermediate transfer belt 8A is returned to the initial state by being removed by a belt cleaning unit (not shown). Thus, a series of transfer processes performed on the intermediate transfer belt 8A is completed.

  Here, the recording medium P transported to the position of the secondary transfer nip is transported from a paper feeding unit 26 disposed below the apparatus main body 100 via a paper feeding roller 27, a registration roller pair 28, and the like. It is a thing. Specifically, a plurality of recording media P such as transfer paper are stored in the paper supply unit 26 in a stacked manner. When the paper feed roller 27 is driven to rotate counterclockwise in FIG. 1, the uppermost recording medium P is fed toward the rollers of the registration roller pair 28. The recording medium P transported to the registration roller pair 28 temporarily stops at the position of the roller nip of the registration roller pair 28 whose rotation drive has been stopped. Then, the registration roller pair 28 is rotated in synchronization with the color image on the intermediate transfer belt 8A, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

  Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing unit 20. At this position, the color image transferred on the surface is fixed on the recording medium P by heat and pressure generated by the fixing roller and the pressure roller. After fixing, the recording medium P is discharged out of the apparatus through a pair of paper discharge roller pairs 29. The recording medium P discharged from the apparatus main body 100 by the discharge roller pair 29 is sequentially stacked on the stack unit 30 as an output image. Thus, a series of color image forming processes in the image forming apparatus is completed.

Next, referring to FIG. 2, a configuration example of the developing device in the image forming unit will be described in more detail.
FIG. 2 is a schematic cross-sectional view of the process cartridge 40 used in the image forming unit 6, which is detachably attached to the image forming units 6Y, 6M, 6C, and 6Bk of each color shown in FIG. In FIG. 2, the developing unit (developing device) 5 includes a casing 50 as a case, a developing roller 51 as a developer carrying member disposed in the casing 50 and facing the photosensitive drum 1, and a developing roller 51. A developer blade 52 as a developer regulating member installed below the developer, a developer collecting chamber and a supply corresponding to a developer collecting section and a developer supplying section, each of which is a space disposed in the longitudinal direction of the casing 50. First and second transport members (hereinafter referred to as first transport screws, hereinafter) composed of developer transport chambers 58 and 59 and screw members serving as developer transport members disposed in the transport chambers 58 and 59. 53 and 54). The recovered developer transport chamber 58 and the supply developer transport chamber 59 contain a two-component developer composed of a carrier and toner. The toner used for the developer in the present embodiment is one having a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. A supply developer transport chamber 58 serving as a developer supply unit is located at the lower part in the vertical direction and supplies the developer toward the developing roller 51.

  A toner concentration sensor 56 for detecting the toner concentration in the developer is provided at a position facing the conveying screw 54 of the casing 50. Of the two transport screws, the first transport screw 53 is a recovery screw serving as a recovery transport member that mixes and stirs the developer and supply toner that faces the developing roller 51 and leaves the developing roller 51. The second conveying screw 54 is a supply screw serving as a conveying member for supplying the developer to the developing roller 51 while conveying the developer in the longitudinal direction while facing the developing roller 51 substantially downward. , 54 is configured such that the rotation direction is set in the reverse direction, whereby the developer is moved in the relative direction to circulate the developer in a direction perpendicular to the paper surface shown in FIG.

FIG. 3 is a schematic cross-sectional view for explaining a developer supply / recovery state in the developing device, and FIG. 4 is a perspective view of the developing device shown in FIG. The basic configuration of this developing device is the same as that incorporated in the image forming unit (process cartridge) 6 of FIG. As shown in FIG. 3, the developing roller 51 includes a magnet roller 55 having a plurality of magnetic poles fixed inside, a cylindrical developing sleeve 51 a that rotates around the magnet roller 55, and the like. For example, five magnetic poles of P1 to P5 poles are formed on the magnet roller of the developing roller 51. Then, when the developing sleeve 51a rotates around the magnet roller 55 on which the five magnetic poles are formed, the developer moves on the developing roller 51 (on the developing sleeve) along with the rotation. Note that the radial curve attached to the magnet roller 55 of the developing roller 51 in FIG. 3 indicates the respective magnetic field (magnetic force) regions of the P1 pole to the P5 pole. The P1 pole is a main magnetic pole for forming a developer magnetic brush in the development region, the P2 pole is a transport magnetic pole, the P3 pole is an agent separation pre-pole, the P4 pole is an agent separation magnetic pole, and the P5 pole is a pumping pole.
In FIG. 3, a magnet roller having five magnetic poles (P1 to P5 poles) is formed. However, the number of magnetic poles is not limited to five, and may be four or six. Instead of the magnet roller, a plurality of fixed magnets may be arranged. The polarities (N pole and S pole) of the P1 pole to P5 pole shown in FIG. 3 are examples, and the N pole and the S pole may be reversed.

Next, a configuration example of a developing device of the one-way circulation development type will be described.
The developing device 5 shown in FIG. 3 accommodates a developing roller 51, a doctor blade 52, a first conveying screw 53, a recovered developer conveying chamber 58 as a developer accommodating portion accommodating the developing roller 51, a second conveying screw 54, and the second conveying screw 54. A supply developer transport chamber 59 as a developer accommodating portion and a shielding member 57 that shields and separates the spaces between the two developer transport chambers 58 and 59 are configured. In each developer transport chamber 58, 59 in the casing 50 of the developing device 5, toner (grain total: 5.2 μm) mainly composed of polyester resin and carrier (particle diameter: 35 μm) made of magnetic fine particles are uniformly 7 wt%. The mixed developer is filled with a certain amount (for example, 300 g), and the toner stirring after replenishment is performed by rotating the first transport screw 53 and the second transport screw 54 arranged in parallel at a predetermined rotational speed (for example, 600 rpm). The toner and carrier are uniformly mixed and charged.
The uniformly mixed developer is agitated and conveyed along the axial direction corresponding to the longitudinal direction by a second conveying screw 54 provided parallel to the developing sleeve 51a of the developing roller 51, and is contained in the developing sleeve 51a. It is transferred to the surface of the outer peripheral portion of the developing sleeve by the magnetic force of the P4 and P5 magnetic poles of the mag roller 55. When the developing sleeve 51a rotates as shown by an arrow in the drawing, the developer is carried to a developing area formed by the photosensitive member 1 and the developing sleeve 51a, and a developing electric field by a high voltage power source (not shown) is formed, so that the toner on the photosensitive member Develop the latent image. The developed developer is collected in the casing 50 as the developing sleeve 51 a rotates, and is collected in the first conveying screw 53 via the shielding member 57.

FIG. 5 is an arrow view in the direction indicated by arrow A in FIG. 4, in which the castle wall of the developing container is removed. In FIG. 5, the arrow indicates the moving direction of the developer. In (A-1), the developer is recovered from the developing sleeve 51 a toward the first transport screw 53 in the recovered developer transport chamber 58. In this case, the moving direction of the developer in the first conveying screw 53 is shown. (A-2) is the figure by the front view of (A-1).
FIG. 5B shows the moving direction of the developer by the first and second transport screws 53 and 54 in the recovered developer transport chamber 58 and the supplied developer transport chamber 59. In the same figure, in the regions a and b at the screw end, the agitation / conveying chamber as a space by the upper recovery screw and the lower supply screw communicates vertically, and from the upper part to the lower stage in the part a serving as a communication part, In the part b which is a communication part, the developer is conveyed from the lower stage to the upper stage. As for the shape of the screw in the part a and the part b (communication part), a paddle or a reverse-wound screw is provided, and it has a conveying ability in a direction perpendicular to the conveying direction. That is, the developing device 5 includes a communication portion for circulating and conveying the developer disposed at both ends in the longitudinal direction of the two spaces.

FIG. 6 is a schematic cross-sectional view showing the movement of the developer in the longitudinal direction of the developing device shown in FIGS.
As shown in FIG. 6, in the supply developer transport chamber 59, the developer is transported by the second transport screw 54 as shown by the thick arrow, and the developer transported by the second transport screw 54 is the developing roller 51. It is pumped up onto the developing sleeve 51a by the magnetic force.
The developed developer is separated from the developing sleeve 51 a of the developing roller 51 through the shielding member 57 and sent into the collected developer conveying chamber 58 on the first conveying screw 53 side. The two developer conveyance chambers 58 and 59 are communicated by the absence of a part of the shielding member 57 outside the development region of the developing roller 51 and are not used for the development conveyed by the second conveyance screw 54. The developer is transferred from the communicating portion on the downstream side in the transport direction of the second transport screw 54 to the collected developer transport chamber 58 on the first transport screw 53 side.

  As shown in FIGS. 4 and 6, the collected developer conveyance chamber 58 in which the first conveyance screw 53 is disposed is provided with a toner supply port TI outside the screw blade region of the first conveyance screw 53. The toner is replenished from the toner replenishing port TI, mixed with the developer delivered from the second conveying screw 54, and conveyed by stirring. The developer recovered from the developing roller 51 after development is mixed with the developer stirred and transported by the first transport screw 53, and similarly stirred and transported. The developer stirred and transported by the first transport screw 53 is delivered to the supply developer transport chamber 59 in which the second transport screw 54 is disposed at a communication portion located downstream of the recovered developer transport chamber 58 in the transport direction. It is.

  As described above, in the developing device 5 of the present invention, the developer is circulated and conveyed in one direction by the second conveying screw 54 and the first conveying screw 53, and is supplied to the developing roller 51 in the conveying process, from the developing roller 51. Is collected and toner is replenished.

Next, characteristic components of the present invention will be described.
(First embodiment)
In the present embodiment shown in FIG. 7A, the present invention is applied to a developing device of a unidirectional circulation development system.
The surfaces of the first transport screw 53 and the second transport screw 54, which are developer transport members provided in the developing device 5, are surfaces that contact the developer G in the casing 50. The surface of the two conveying screws 54 is made to have a developer difficult adhesion property. The surface of the 1st conveyance screw 53 and the 2nd conveyance screw 54 is a contact part with the developing agent G with which the 1st conveyance screw 53 and the 2nd conveyance screw 54 are equipped, and each axis | shaft 53a, 54a and each axis | shaft are These are the surfaces of the formed spiral blades 53b and 54b. Hereinafter, the first transport screw 53 and the second transport screw 54 may be simply referred to as screws hereinafter.
As a specific example of the method of making the developer difficult to adhere to the screw, both ends of the screw extending in the longitudinal direction are masked, and the other part is coated with a material having the developer difficult adhesion property using a spray. As shown in FIG. 7B, surfaces 90 having the developer difficult adhesion property indicated by dotted lines were formed on the surfaces of the screws 53 and 54, respectively.
In order to verify the effects of the screws (first conveying screw 53 and second conveying screw 54) having such a developer difficult adhesion characteristic, as a result of running in a low image area with little toner replacement, The developer did not stick even when the developer fluidity deteriorated. There was no abnormal image due to insufficient dispersion of replenished toner, and the amount of discharged developer replacement was improved to the same level as the initial agent. For this reason, the labor of the operator when changing the developer can be simplified. The developer difficult adhesion property will be described later.

Next, a modification of the first embodiment will be described.
(Modification 1)
In the first modification, as shown in FIG. 8A, the shafts 53a and 54a and the spiral blades 53b that are the same as the first embodiment of the screw (the first transport screw 53 and the second transport screw 54), Instead of spray coating, a sheet material 901 having a difficult adhesion property was attached to the surface of 54b to form a surface 90 having a developer difficult adhesion property. The sheet material 901 having a difficult adhesion property of the developer has a thickness of 100 μm and has an adhesive layer on the back side, and fits the shape of each screw shaft 53a, 54a and the spiral blades 53b, 54b or the spiral blade. Cut and affixed to each part of the screw.
In order to verify the effects of the screws (first conveying screw 53 and second conveying screw 54) having such a developer difficult adhesion characteristic, as a result of running in a low image area with little toner replacement, The developer did not stick even when the developer fluidity deteriorated. There was no abnormal image due to insufficient dispersion of the replenished toner, and the discharge amount of the automatic developer change was improved to the same level as the initial agent, so that the labor of the operator when changing the developer could be simplified.

(Modification 2)
In the first modification, a sheet material 901 having a developer difficult adhesion property is attached to the screws 53 and 54 to form a developer difficult adhesion surface 90 on the surface of the screw, thereby providing the developer difficult adhesion property. However, in the second modification, as shown in FIG. 8 (b), the screw surface itself has a difficult adhesion property. Specifically, the surface 90 having the developer difficult adhesion property was provided on the surface by forming a screw with the material 902 having the developer difficult adhesion property. In this case, it is possible to easily provide the screw surface with a difficult adhesion property, rather than attaching the sheet material 901 to the surface of the screw having a curved surface. Note that the method of forming the surface 90 having the developer difficult adhesion property is not limited thereto.

(Modification 3)
In the third modification, a screw having a difficult adhesion property of a developer is applied to a developing device of a biaxial circulation type. A target biaxial circulation developing device will be described with reference to FIG.
The developing device 150 shown in FIG. 9A constitutes a part of a process cartridge 401 that is detachably installed on the apparatus main body 100. The developing device 150 includes a developing roller 151 as a developer carrying member, a doctor blade 152 as a developer regulating member, a first conveying screw 153 as a developer conveying member, a recovered developer conveying chamber 158 that accommodates the developer conveying chamber 158, and a developer. A second conveying screw 154 as a conveying member, a supply developer conveying chamber 159 that accommodates the second conveying screw 154, and a shielding member 157 that shields and separates the spaces of these two developer conveying chambers 158 and 159 are provided. In the developer transport chambers 158 and 159 in the casing 160 of the developing device 150, a toner mainly composed of polyester resin (a total particle size of 5.2 μm) and a magnetic fine particle carrier (a particle size of 35 μm) are uniformly 7 wt%. A fixed amount (for example, 300 g) of the mixed developer G is filled, and the first conveyance screw 153 and the second conveyance screw 154 that are arranged in parallel with each other are rotated at a predetermined rotation number (for example, 600 rpm), so that The toner is stirred and transported at the same time, and the toner and carrier are uniformly mixed and charged.

  The uniformly mixed developer G is agitated and conveyed along the axial direction corresponding to the longitudinal direction by a second conveying screw 154 provided in parallel with the developing sleeve 151a of the developing roller 151, and is contained in the developing sleeve 151a. It is transferred to the surface of the outer peripheral portion of the developing sleeve by the magnetic force of the magnet roller. When the developing sleeve 151a rotates as indicated by the arrow in the figure, the developer G is carried to the developing area formed by the photosensitive member 101 as the image carrier and the developing sleeve 151a, thereby forming a developing electric field by a high voltage power source (not shown). The toner develops the latent image on the photoreceptor 101. The developed developer G is collected in the casing 160 as the developing sleeve 151 a rotates, and is collected in the first conveying screw 153 via the shielding member 157. Further, replenished developer is supplied from the toner replenishing device to the collected developer transport chamber 158 via the supply path 164.

Even in such a biaxial circulation type developing device 150, if the developer adheres to the screws 153 and 154 over time, the dispersibility of the replenishing toner deteriorates, or the fixation peels off due to some reason, and the solidification is caused. When the adhering material clogs the doctor gap formed between the developing roller 151 and the doctor blade 152, white stripes are formed, and when the adhering material passes through the doctor gap as an aggregate, black spots are formed. Therefore, it is very important not to fix the developer to the screws 153 and 154.
In the third modification, the two screws 153 and 154 are surfaces that contact the developer G in the casing 160, and the shafts 153a and 154a and the shafts 153a and 154a included in the two screws 153 and 154 are provided. On the surface of the spiral blades 153b and 154b formed in Fig. 9B, a surface 90 having a developer difficult adhesion property is formed as shown by a dotted line in FIG.
In order to verify the effects of the screws 153 and 154 having such a developer difficult adhesion property, the flow of the developer deteriorated with time as a result of running in a low image area with little toner replacement. Sometimes the developer did not stick.

(Modification 4)
In the fourth modification, an example will be described in which the present invention is applied to a developing device including three developer conveying members that convey the developer.
The developing device 200 shown in FIGS. 10 and 11 constitutes a process cartridge 402 that is detachably installed on the apparatus main body 100. Of course, the developing device 200 alone may be detachable from the apparatus main body 100 separately from the process cartridge 402.

Hereinafter, the configuration and operation of the developing device 200 will be described in detail.
As shown in FIG. 10A, the developing device 200 includes two developing rollers 23a1, 23a2, a plurality of developer conveying members 23b1, 26b2, 23b3 (auger screws), a doctor, and the like in a casing 201. The blade 23c, the carrier collecting roller 23k, the scraper 23m, the discharge screw 23n, the upper case 23r as a case member, and the like. In addition, in the casing 201 of the developing device 200, three transport units B1 to B3 that transport the developer G and form a circulation path (transport path) are formed. Developer G is a two-component developer including toner T and carrier C.

  The developing rollers 23a1 and 23a2 as the developer carrying members are configured such that a sleeve formed of a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin in a cylindrical shape is rotated clockwise by a rotation driving mechanism. Has been. In the sleeves of the developing rollers 23a1 and 23a2, a magnet for forming a magnetic field is fixed so as to cause the developer G to rise on the peripheral surface of the sleeve. The carrier C in the developer G rises in a chain shape on the sleeve so as to follow the normal magnetic field lines emitted from the magnet. The charged toner T is attached to the carrier C that is spiked in a chain shape to form a magnetic brush. The magnetic brush is transferred in the same direction (clockwise) as the sleeve by the rotation of the sleeve.

Specifically, a plurality of magnetic poles are formed around the developing rollers 23a1 and 23a2 by magnets in the sleeve, respectively. Around the first developing roller 23a1, there are a pumping magnetic pole for pumping up the developer G accommodated in the first developer transport unit B1, a doctor-facing magnetic pole formed at a position facing the doctor blade 23c, and a photosensitive member. A main magnetic pole formed in a region facing the body drum 21, a transport magnetic pole for transporting the developer to a position facing the second developing roller 23a2, and the like are formed.
Around the second developing roller 23a2, there are a receiving magnetic pole for receiving the developer G on the first developing roller 23a1, a main magnetic pole formed in a region facing the photosensitive drum 21, and a carrier collecting roller 23k. And a collecting roller counter magnetic pole formed at the opposite position, a agent separating magnetic pole (agent separating pole) for separating the developer toward the second developer conveying portion B2, and the like.

  The doctor blade 23c as a developer regulating member is installed on the upstream side of the developing area, and regulates the developer G carried on the first developing roller 23a1 to an appropriate amount. The doctor blade 23c in the present modification is a plate-like member having a plate thickness of about 2 mm formed of a nonmagnetic metal material such as SUS316 or XM7. Note that a thin plate having a thickness of about 0.3 mm made of a magnetic metal material such as SUS430 can be installed on the opposite surface 23c side of the doctor blade 23c.

  Each of the three transport screws 23b1 to 23b3 has a screw portion spirally formed on the shaft portion, and the developer G accommodated in the developing device 200 is placed in the longitudinal direction (perpendicular to the paper surface in FIG. 10A). Stir and mix while circulating in the direction. Of the three screws, a first transport screw 23b1 as a first developer transport member is disposed at a position facing the developing roller 23a1 in the first developer transport section B1, and the developer G The developer 23a is supplied onto the developing roller 23a1 while being conveyed in the horizontal direction (the conveyance in the left direction indicated by the white arrow in FIG. 11). In other words, the first transport screw 23b1 faces the developing roller 23a1 and supplies the developer G to the developing roller 23a1 while transporting the developer G in the longitudinal direction (the rotational axis direction of the developing roller 23a1).

  The second transport screw 23b2 as the second developer transport member is installed in the second developer transport section B2. The second transport screw 23b2 is disposed below the first transport screw 23b1 and at a position facing the developing roller 23a2. Then, the developer G separated from the developing roller 23a2 (the developer G forcibly separated from the developing roller 23a2 by the agent separation pole after the developing step) is conveyed in the horizontal direction (indicated by a white arrow in FIG. 11). (Left direction transport). In other words, the second conveying screw 23b2 is disposed at a position below the first developer conveying portion B1 and facing the developing roller 23a2, and the developer G detached from the developing roller 23a2 is disposed in the longitudinal direction. Transport. The first transport screw 23b1 and the second transport screw 23b2 are arranged so that the rotation axis is substantially horizontal, like the developing rollers 23a1 and 23a2 and the photosensitive drum 21.

A third transport screw 23b3 as a third developer transport member is installed in the third developer transport section B3. The third conveyance screw 23b3 is disposed obliquely with respect to the horizontal direction so as to linearly connect the downstream side of the conveyance path by the second conveyance screw 23b2 and the upstream side of the conveyance path by the first conveyance screw 23b1. (See FIG. 11). The third transport screw 23b3 transports the developer G transported by the second transport screw 23b2 to the upstream side of the transport path by the first transport screw 23b1, and the fall path from the downstream side of the transport path by the first transport screw 23b1. The developer G circulated through 23f is transported to the upstream side of the transport path by the first transport screw 23b1 (conveying upward diagonally to the right indicated by the white arrow in FIG. 11). In other words, the third transport screw 23b3 transports the developer G transported by the second developer transport section B2 to the upstream side of the first developer transport section B1, and downstream of the first developer transport section B1. The developer G that has reached 1 is conveyed to the upstream side of the first developer conveyance part B1.
In other words, the first developer conveyance unit B1 constitutes a developer recovery unit, the second developer conveyance unit B2 constitutes a developer supply unit, and the third developer conveyance unit B3 constitutes a developer conveyance unit. Yes.

  A transport path (first developer transport section B1) by the first transport screw 23b1, a transport path by the second transport screw 23b2 (second developer transport section B2), and a transport path (first transport by the third transport screw 23b3). 3 is separated from the developer conveying portion B3) by a wall portion. Referring to FIG. 11, the downstream side of the second developer transport unit B2 and the upstream side of the third developer transport unit B3 communicate with each other via a first relay unit 23g serving as a communication unit. The downstream side of the third developer conveyance unit B3 and the upstream side of the first developer conveyance unit B1 are communicated with each other via a second relay unit 23h serving as a communication unit. The downstream side of the first developer transport unit B1 and the upstream side of the third developer transport unit B3 communicate with each other via a drop path 23f.

  With such a configuration, a circulation path for circulating the developer G in the longitudinal direction in the developing device 200 is formed by the conveying screws 23b1 to 23b3 of the three developer conveying portions B1 to B3. Here, when the developing device 200 is operated, the developer G accommodated in the device flows in a state as indicated by the oblique lines in FIG. Referring to FIG. 11, in the first developer conveying section B1, the developer surface on the downstream side is lower than the upstream agent surface because part of the developer being conveyed is developed. This is because it is supplied to the roller 23a1. That is, the developer that has not been supplied to the developing roller 23a1 moves to the upstream side of the third developer conveying portion B3 via the dropping path 23f.

In the fourth modification, in such a developing device 200, the surfaces of the conveying screws 23b1 to 23b3 of the three developer conveying portions B1 to B3 in the casing 201 are surfaces that come into contact with the developer in the casing 201. For this reason, the surfaces of the transport screws 23b1 to 23b3 are surfaces having developer difficult adhesion characteristics. That is, the surfaces of the shafts 23b1a to 23b3a of the conveying screws 23b1 to 23b3 and the surfaces of the spiral blades 23b1b to 23b3b formed on the respective shafts, which are contact surfaces with the developer G, are indicated by dotted lines in FIG. In this way, the surface 90 having the developer difficult adhesion property was formed to obtain a surface having the developer difficult adhesion property.
In order to verify the effect of the conveying screws 23b1 to 23b3 having such a developer difficult adhesion property, the running of the developer with a low image area with less toner replacement results in a deterioration of the developer fluidity with time. At that time, the developer G was not fixed. There was no abnormal image due to insufficient dispersion of the replenished toner, and the discharge amount of the automatic developer change was improved to the same level as the initial agent, so that the labor of the operator when changing the developer could be simplified.

In the first embodiment and each of the modified examples, the surface of each screw as a developer conveying member built in each developing device is given a developer difficult adhesion property or is in contact with the developer in each screw. The portion to be made was formed of a material having a developer difficult adhesion property.
In the fifth and subsequent modifications, the surface of the portion that contacts the developer in the case of the developing device, not the developer conveying member, has a developer difficult adhesion property. Since the mechanical configuration of the developing device after the modification 5 is the same as that of the first embodiment to the modification 4, it will be described using the configuration of the developing device used in these embodiments.

Claim 9
(Modification 5)
Modification 5 will be described as an example applied to the developing device 5. FIG. 12 shows the flow of the developer in the developing device 5. The developed developer leaves the developing roller 51 at the P4 pole, and is sent to the screw 53 via the collection guide 57a which is the collection unit side surface of the shielding member 57. Note that the collection guide 57a is formed to have at least the length of the developing row 51 in the longitudinal direction. The developer moves from the developing roller 51 to the first conveying screw 53 by its own weight in a fluidized state. For this reason, when the fluidity of the developer deteriorates due to deterioration with time or environmental fluctuation, the developer may stay on the collection guide 57a without moving by its own weight.

  In the present modified example 5, in the casing 50 of the developing device 5 as described above, the developer contact surface is in contact with the developer in the case and has a developer difficult adhesion property on the transport path where the developer tends to stay. A surface to be a surface was formed. Specifically, a surface 91 having a developer difficult adhesion property as shown by a dotted line is formed on the surface 57a of the shielding member 57 (the surface of the collection guide 57a).

  Thereby, even if the developer is moved at the interface with the collection guide 57a even in a poor fluidity state, it is possible to prevent the developer from staying. For this reason, density unevenness due to poor developer recovery can be prevented. Furthermore, the developer sticking to the collection guide 57a can be suppressed, and abnormal images such as white stripes and spots caused by the sticking object can be prevented.

  As a result of intensive studies by the inventors, in the configuration of the developing device 5 as described in the fifth modification, most of the developer staying and fixing in the casing 50 is collected in the collected developer transport chamber 58. It was confirmed that this occurred in the guide 57a. For this reason, it has been clarified that a sufficient effect can be obtained for abnormal images such as white stripes and spots only by forming a surface having a developer difficult adhesion property only on the surface of the collection guide 57a. Further, since it is formed only on the surface of the collection guide 57a, the effect can be obtained at a lower cost than the case where it is formed on the entire collection developer conveyance chamber 58.

(Modification 6)
In the modified example 6, as shown in FIG. 13, the collection guide 57 a that is a downwardly inclined surface toward the collected developer transport chamber 58 as viewed from the developing roller 51 extends below the screw 53. Therefore, the surface having the developer difficult adhesion property is not formed on the portion 57a1 of the recovery guide 57a located in the region Z in the two tangents X1 and X2 of the outer diameter line of the screw 53 directed downward in the gravity direction. did. That is, in the recovered developer transport chamber 58, the surface 58a of the recovered developer transport chamber 58 and the surface 57a1 of the recovery guide 57a, which are located in the region Z located below the screw 53, have a developer difficult adhesion property. 91 is not provided. This is because the developer is transported by the screw 53 in the region Z. Therefore, when the developer transport speed is fast or when the distance between the screw 53 and the collection guide 57a is short, this development is caused by a strong pressure. The surface having the difficult adhesion property of the developer is worn away or peeled off, and not only the sticking suppression effect disappears, but also the property of the developer changes depending on the surface having the difficult adhesion property of the developer. In consideration of this, an abnormal image is generated.

  In other words, in the developing device 5 under such conditions, since the developer moves actively in the region Z, the developer does not stay in this portion. Accordingly, the region Z in the two tangents X1 and X2 directed downward in the direction of gravity of the outer diameter line of the screw 53 is made to have non-developer difficult adhesion characteristics, so that the developer stays and adheres to the collection guide 57a. The occurrence of abnormal images can also be suppressed while suppressing for a long time.

In the modified examples 5 and 6, as a technique for characterizing the developer difficult adhesion on the surface of the collection guide 73a, a sheet material having a developer difficult adhesion characteristic is attached to the collection guide 73a, or a liquid material is sprayed. The method is applicable.
The method of making the surface of the collection guide 57a the surface 91 having the developer difficult adhesion property is not limited to this. For example, the resin or metal forming the shielding member 57 is a material having the developer difficult adhesion property. It may be formed so as to have a developer difficult adhesion property, or a coating method such as dipping such as immersion molding or immersion coating may be applied to the collection guide 57a.
The collection guide 57a is inclined, but its surface is a flat surface. For this reason, it is preferable because it is possible to easily stick a sheet material or the like having a developer difficult adhesion property while at the same time preventing retention of the developer derived from the surface shape.

In the first embodiment and the first to fourth modifications, a surface 90 having a developer difficult adhesion property is formed on the developer transport member in the developing device, and the fifth and sixth modifications are images on the transport path in the developing device. Although the surface 91 having the developer difficult adhesion property is formed, the surface having the developer difficult adhesion property is formed on both the developer conveying member and the conveying path in one developing device, so that the inside of the developing device with time It is possible to reduce the number of fixing points of the developer, and to suppress the developer in the developing device over time. For this reason, even when the toner deteriorates over time, the occurrence of abnormal images can be further reduced, and it is not necessary to peel off and remove the fixed developer when the developer is replaced. This will lead to further suppression of cost increase by increasing man-hours.
In the fourth embodiment to the fourth modification, the surface 90 having the developer difficult adhesion property is formed on the surface of all the developer conveying members. However, when a plurality of developer conveying members are provided, at least one of the developments is performed. It can be said that forming the surface 90 having the developer difficult adhesion property on the surface of the agent conveying member is also preferable because the fixing of the developer in the developing device with time can be suppressed.
In the first embodiment and the first to fourth modifications, the surface 90 having the developer difficult adhesion property is formed in the entire region of the axis of the developer conveying member extending in the axial direction and the spiral blade, but the axis of the developer conveying member Even if the surface 90 having the developer difficult adhesion property is formed around the part of the developer conveying member, which corresponds to the part where the developer that has deteriorated by being used for development is collected and conveyed, for example, instead of the entire region in the direction, It can be said that it is preferable because the fixing of the developer at the portion is suppressed.
In the modified examples 5 and 6, the recovery guide 58 has the surface 91 having the developer difficult adhesion property as a transport path in the developing device. However, the surface 91 is not limited to this portion, and is positioned in the longitudinal direction of a plurality of spaces. Even if the surface 91 having the developer difficult adhesion property is formed on the surface of the communicating portion for circulating and conveying the developer by communicating with each space at both ends, the adhesion of the developer is suppressed. This can be said to be a preferred embodiment.

  Making the portion in contact with the developer in the casing of the developing device a surface having the developer difficult adhesion property means that the contact portion or the surface of the member is made to have the developer difficult adhesion property. Making the developer difficult adhesion characteristic is one technique in which a developer difficult adhesion characteristic layer is formed on the surface of a member or part to be made difficult to develop with a material having the developer difficult adhesion characteristic. Another method is to form a portion or a member in contact with the developer in the casing with a material having a developer difficult adhesion property, and as a result, to make the surface of the developer difficult adhesion property. That is, the characteristics of the part that comes into contact with the developer in the casing and the developer difficult adhesion characterization on the surface of the member are not limited to being achieved by surface treatment or surface processing, but the part that comes into contact with the developer in the casing. It also includes forming and molding the member and the member with a material having a developer difficult adhesion property.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the application portion of the invention is changed from a developing device to a developer recovery conveyance path. The schematic configuration and operation of the image forming apparatus to which the second embodiment is applied will be described with reference to FIG.

The image forming apparatus shown in FIG. 14 exemplifies a monochrome copying machine. The copying machine main body 500 is placed on a sheet bank 502. An image reading apparatus 501 is attached on the apparatus main body 500. The image reading apparatus 501 includes a contact glass 557 on which a document is placed, and an automatic document feeder 503 that can be opened and closed up and down is provided above the contact glass 557.
Inside the apparatus main body 500, a drum-shaped photoconductor 510 that is an image carrier and extends in the direction perpendicular to the paper surface is provided. A charging device 511 is disposed on the left side of the periphery of the photoreceptor 510, and a developing device 600, a transfer device 513, and a cleaning device 514 are sequentially disposed in the rotation direction (counterclockwise) of the photoreceptor 510.

  The developing device 600 supplies the developer to the electrostatic latent image on the photoreceptor 510 by a developing roller 604 serving as a developer image carrier, and visualizes the electrostatic latent image. The transfer device 513 includes a transfer belt 517 that is an image carrier and an intermediate transfer member wound between upper and lower rollers, and the transfer belt 517 is pressed against the peripheral surface of the photoconductor 510 at the transfer position N. It is in contact. A toner replenishing device 520 is disposed on the left side of the charging device 511 and the cleaning device 514, and new toner is replenished to the developing device 600 by the toner replenishing device 20. On the left side of the developing device 600 in the drawing, a laser writing device 547 for irradiating exposure light is disposed.

Inside the apparatus main body 500, a sheet conveyance path R is formed that conveys the recording medium P sent from the sheet cassette 561 in the sheet bank 502 from the lower side to the upper side through the transfer position N to the paper discharge stack unit 539. ing. In the sheet conveyance path R, a registration roller 521 is provided at an upstream position of the photoconductor 510.
A fixing device 522 is provided at a downstream position of the photoconductor 510. A discharge branch claw 534 and a discharge roller 535 are provided further downstream of the fixing device 522, and a discharge stack portion 539 for stacking the recording medium P on which an image has been formed is further provided.

  In the apparatus main body 500, a switchback device 550 is provided on the apparatus main body surface on the right side in FIG. The switchback device 550 reverses the recording medium P printed on one side and passed through the fixing device 522 during double-sided printing, and guides it to the transfer position N.

Inside the sheet bank 502, sheet cassettes 561 for storing recording media P such as sheets and OHP films are provided in multiple stages. Each sheet cassette 561 is provided with a call roller 562, a supply roller 563, and a separation roller 564 correspondingly. The sheet cassettes 561 provided in multiple stages are connected to the sheet conveyance path R.
The apparatus main body 500 is provided with a manual feed unit 568 below the switchback device 550. A manual feed tray 567 is provided in the manual feed unit 568 so as to be freely opened and closed, and a manual recording medium P set on the manual feed tray 567 is connected to the sheet conveyance path R. Similarly, the manual feed tray 567 is provided with a calling roller 562, a supply roller 563, and a separation roller 564.

An operation at the time of image formation in the copying machine having such a configuration will be described.
Here, it is assumed that a document is set on the contact glass 557. When the start switch of the copying machine is pressed, the image reading device 501 operates to read the original image. At the same time, the photoconductor 510 is rotated by the photoconductor drive motor, the surface of the photoconductor 510 is uniformly charged by the charging device 511 using the charging roller, and then the original is read by the image reading device 501. A writing process is performed by irradiating a laser beam from the laser writing device 547 to form an electrostatic latent image on the surface of the photoconductor 510, and then the developing device 600 is used to attach the toner in the developer to electrostatically. The latent image is visualized (developed).

  When the start switch is pressed, the recording medium P selected from the multi-stage sheet cassette 561 in the sheet bank 502 is sent out by the calling roller 562, separated one by one by the supply roller 563 and the separation roller 564, and sent to the sheet conveyance path R. It is done. The recording medium P sent to the sheet conveyance path R is conveyed by the sheet conveyance roller 566, guided to the sheet conveyance path R, stopped by abutting against the registration roller 521, and the toner image visualized on the photoreceptor 510. Are sent to the right side of the photosensitive member 510 at the same timing. When the manual paper feed unit 568 is used, the manual feed tray 567 is opened, and the recording medium P set on the opened manual feed tray 567 is sent out by the calling roller 562 and 1 by the supply roller 563 and the separation roller 564. Each sheet is separated and conveyed and guided to the sheet conveyance path R. Similarly, the registration roller 521 feeds the photosensitive member 510 to the right side in time with the rotation of the photosensitive member 510.

  Thereafter, the recording medium P fed to the right side of the photoconductor 510 is transferred with the toner image on the photoconductor 510 by the transfer device 513 at the transfer position N. The toner that becomes the developer remaining on the photoconductor 510 after the image transfer is removed, cleaned, and collected by the cleaning device 514, and the residual potential on the photoconductor 510 from which the residual toner has been removed is removed by the static eliminator. . In preparation for the next image formation starting from the charging device 511.

On the other hand, the recording medium P after the image transfer is conveyed by the transfer belt 17 and guided to the fixing device 522, and heat and pressure are applied to fix the toner image. Thereafter, the recording medium P on which the image is fixed is discharged onto the paper discharge stack unit 539 by the paper discharge roller 535 and stacked.
In addition, when transferring an image to both surfaces of the recording medium P, the discharge branch claw 534 is switched, and the recording medium P on which the toner image is transferred onto the surface is carried into the switchback device 550 from the sheet conveyance path R. After being switched back and guided again from the sheet conveyance path R to the transfer position N, the image is also transferred to the back surface of the recording medium P in the same manner as described above.

Next, the configuration of the developing device 600 and the toner supply operation to the developing device 600 will be described with reference to FIGS.
The developing device 600 includes a developing roller 604 and helical conveying screws 601 and 602 as developer conveying members, and a two-component developer G composed of a carrier and toner is conveyed in the direction perpendicular to the paper surface by the conveying screws 601 and 602. The developer G is supplied to the developing roller 604 while being conveyed. That is, the transport screw 601 is rotatably supported in a transport path 611 formed in the developing device 600 so as to extend in the direction perpendicular to the paper surface, and transports the developer G from the back side of the paper surface toward the front side of the paper surface. . The transport screw 602 is rotatably supported in a transport path 612 formed in the developing device 600 so as to extend in the direction perpendicular to the paper surface, and transports the developer G from the front side of the paper surface toward the back of the paper surface. The conveyance path 611 and the conveyance path 612 are connected by an end located in the direction perpendicular to the paper surface so that the developer conveyed by the conveyance screws 601 and 602 circulates between the conveyance path 611 and the conveyance path 612. It is configured.
A developing roller 604 is disposed in the conveyance path 611 so as to be parallel to the conveyance screw 601. The developer G transported by the transport screw 601 rotates in the clockwise direction, and the magnet is pumped up to the developing roller 604 with a built-in magnet. A large amount of the developer G pumped up by the magnetic force is regulated to a constant amount by a developing doctor 607 as a regulating member and frictionally charged. The charged developer G rises at the main pole of the maximum magnetic strength of the developing roller 604 and comes into contact with the photoreceptor 510. A bias voltage is applied to the developing roller 604, and the toner is selectively developed according to the electrostatic latent image on the photoreceptor 510.

  The photoconductor 510 includes a charging roller 508 that uniformly charges the surface of the photoconductor for exposure, a cleaning blade 541 provided in a cleaning device 514 that cleans the surface of the photoconductor after image formation processing, and a developer scraped by the cleaning blade 541. A process cartridge 650 is configured integrally with a recycle toner transport screw 542 that places the untransferred toner T1 on a recycle toner transport path 590 as a developer recovery section transport path shown in FIG. The process cartridge 650 is configured to be detachable from the apparatus main body 500 of FIG. 14 so that the unit can be easily replaced as necessary. The process cartridge 650 is also detachable from the developing device 600, and is detachable from the apparatus main body 600 integrally with the developing device 600 or separately from the developing device 600. The process cartridge 650 is integrated with the developing device 600 to constitute a process cartridge unit.

The toner concentration of the developer in the developing device 600 shown in FIG. 15 is detected by a toner concentration sensor 605 installed below the conveying screw 602. In the developing device 600, when the value detected by the toner density sensor 605 exceeds the target value (threshold value), new toner is supplied from the toner supply device 520 shown in FIG. 14, and the toner density is controlled to a constant density. Is done.
In this embodiment, toner recycling is performed to return the untransferred toner (collected toner) T1 to the developing device 600, and thus the collected toner T1 is intermittently refluxed. For this reason, the toner density detection during the printing operation is preferably performed at a timing when it is expected that the toner density unevenness in the developing device 600 has been eliminated after a predetermined time has elapsed after the end of the toner recycling operation, for example.
The determination as to whether or not to replenish fresh toner T2 from the toner replenishing device 520 is also expected after the toner recycling operation has been completed, and after the predetermined time has elapsed, toner density unevenness in the developing device 600 due to recycled toner collection has been resolved. It is preferable to carry out at the timing.

In this embodiment, the process cartridge unit (copier) includes a developer recovery unit 700 that returns the transfer residual toner (recovered toner) T1 recovered by the cleaning device 514 to the developing unit 600. In the developer collecting unit 700, a recycled toner conveying screw 542 and a recycled toner conveying screw 542 are disposed as conveying members for conveying the transfer residual toner T1 collected by the cleaning device 514, and the cleaning device 514 and the developing device 600 are disposed. And a recycle toner transport path 590 connected to the.
The recycle toner conveyance path 590 extends in the photosensitive member axial direction, and includes a first conveyance path 591 in which a recycled toner conveyance screw 542 as a conveyance member is disposed, and an end 542a of the first conveyance path 591 located on the front side of the apparatus main body. And a third transport path 593 that connects the second transport path 592 and the developing device 600. In the present embodiment, the first transport path 591 is a substantially horizontal transport path, the second transport path 592 is a transport path inclined obliquely downward from the first transport path 591 toward the third transport path 593, and The three transport paths 593 are formed as substantially vertical transport paths.
The toner recycling is a process of returning the transfer residual toner T1 remaining on the photoreceptor 510 after the transfer process to the developing device 600. That is, the transfer residual toner T1 remaining on the photoconductor 510 after the transfer process is recovered from the photoconductor 510 by the cleaning blade 541 and the recycled toner conveyance screw 542, and is developed via the recycle toner conveyance path 590 shown in FIG. By being supplied to the end 612a of the conveyance path 612 of 600 from above, it is conveyed back into the developing device 600.
Specifically, as shown in FIG. 16, the transfer residual toner T1 scraped off by the cleaning blade 541 is passed through the first conveying path 591 along the photosensitive member axial direction using the recycled toner conveying screw 542. It is sent to the front side, returned to the developing device 600 via the second conveyance path 592 and the third conveyance path 593, and used in the development process. Fresh toner T2 supplied from the toner replenishing device 20 (see FIG. 14) is supplied to the third transport path 593.

  In the present embodiment, the developing roller 604 and the conveying screws 601 and 602 are rotated in order to satisfactorily mix the replenished toner and the developer G in the recovery of the toner end. In order to prevent non-uniform sliding of the developer G on 604, it is preferable to apply driving so that the photosensitive member 510 is also rotated.

  By the way, in the electrophotographic image forming apparatus, as described above, the latent image on the photosensitive member is developed to form a toner image, and the toner image is transferred to a recording medium or an intermediate transfer belt. Transfer residual toner remains on the top. In addition, the charging potential is applied to the image carrier at the start and end of the printing operation, the timing error of the application of the developing bias to the developing unit, the region where the charging potential of the photosensitive member is unstable until the rise is stable, or the charging is unstable. Excess toner other than the original image-forming / transferred toner may be present on the photoreceptor, such as adhesion of the toner to the background of the image carrier. For this reason, the transfer residual toner, which is unnecessary toner, is removed from the photoreceptor by cleaning with a cleaning device. In this embodiment, the transfer residual toner T1 on the photoconductor 510 is removed by the cleaning device 514 and collected.

  In the image forming apparatus, the transfer residual toner collected by the cleaning device is accumulated in the waste toner tank as waste toner, and is collected and discarded during maintenance, as well as from the viewpoint of running cost reduction and environmental considerations. In addition, there is also an image forming apparatus (copier) provided with a recycle toner transport path 590 that recycles the transfer residual toner T1 collected by the cleaning device 514 to the developing device 600 again. In particular, in the case of the direct transfer method in which the toner image T on the photosensitive member 510 is directly transferred to the recording medium P without an intermediate transfer member (intermediate transfer belt) as an image carrier as in the present embodiment, the transfer is performed. The cleaning device 514 collects not only the remaining toner T1 but also foreign matters such as paper dust attached to the photoconductor 510 due to contact between the photoconductor 510 and the recording medium P such as paper.

  After the replenishment of the fresh toner T2 from the toner replenishing device 20, the transfer residual toner T1 is stirred in the developing device 600, formed with a developed image on the photosensitive member 510, passed through the transfer portion, and collected by the cleaning device 514. Stress at each stage is also added. In addition, the cleaning device 514 is structurally disposed on the downstream side of the photosensitive member rotation direction, that is, on the downstream side of the transfer position N, which is the region after transfer to the recording medium P, and similarly on the downstream side of the transfer position N. The fixing device 522 may be disposed relatively close to the fixing device 522. For this reason, the transfer residual toner T1 may be exposed to heat, and wax contained in the collected transfer residual toner T1 or deposited on the surface thereof is melted, and fluidity is likely to deteriorate or agglomerate. Become. Such agglomeration also tends to become large due to adhesion to the paper powder collected together. In recent years, since the melting point of toner has been lowered in order to reduce the environmental burden, it has become important to solve this problem.

  If such a state is repeated or left for a long time, the function and characteristic values of the toner are deteriorated and the toner is deteriorated and transferred onto the recycle toner conveyance path 590 including the inside of the cleaning device 514. The residual toner T1 adheres and solidifies, and a part thereof becomes dead toner that is not conveyed even when the recycled toner conveying screw 542 rotates. Further, the transfer residual toner T1 may be accumulated between the surface of the recycled toner conveying screw 542 serving as the wall surface of the conveying path and the pitch of the screw serving as the gap between the conveying members, and may become dead toner that adheres and adheres. . Then, the occurrence of a phenomenon such as toner overflow or toner spillage due to toner conveyance failure leads to contamination of the apparatus main body 500.

However, such a dead toner is caused by various factors such as attachment / detachment of the process cartridge 650 by the service staff, opening / closing of the paper feeding cassette 561 by the user, opening / closing of the automatic document feeder 503, or movement of the copying machine installation location. 650, the developing device 600, and the vibration applied to the apparatus main body 500 may be peeled off from the surface of the recycle toner transport path 590 or the surface of the recycled toner transport screw 542.
The transfer residual toner T1 that has been peeled off is transported and enters the developing device 600 as the recycled toner transport screw 542 is rotationally driven in the recycle toner transport path 590. When a large amount of toner is replenished to the developing device 600 in a short time, the toner is developed without sufficiently charging the toner, which may cause an abnormal image such as background contamination or toner dropping due to paper dust. .
In particular, in recent years, with the development of a developer having a long life even with a small amount of developer, the amount of the developer has become smaller than that of a conventional developing device. In an image forming apparatus including such a developing device, even if the same toner amount is mixed, the influence is relatively greater than that of a developing device having a large amount of developer.

Therefore, in the second embodiment, as shown in FIGS. 17A and 17B, at least one of the surface 542a of the recycled toner conveying screw 542 or the wall surface 590a of the recycled toner conveying path 590 is attached to the first toner. Similar to the embodiment, the surface 90 has toner adhesion characteristics. The surface having the toner adhesion property means that the surface of the member in contact with the untransferred toner (collected toner, recycled toner) is made the toner adhesion property. As shown in FIG. 17A, the toner difficult adhesion property is formed by forming a toner difficult adhesion characteristic layer on a surface of a member or a portion where the toner difficult adhesion property is desired by using a material having the toner difficult adhesion property. This is one method.
As another method, as shown in FIG. 17B, a recycled toner transport path 590 and a recycled toner transport screw 542 itself are formed from a material 902 having a toner difficult adhesion property. As a result, the surface 542a or For example, the wall surface 590a may be made to have a toner adhesion property. That is, the toner difficult adhesion characterization is not limited to being achieved by surface treatment or surface processing, and includes forming and molding a member with a material having toner difficult adhesion characteristics.

As described above, when the surface 542a of the recycled toner conveying screw 542 has a difficult toner adhesion property, the transfer residual toner T1 is less likely to adhere to the recycled toner conveying screw 542, so that it can be easily removed. Even when the toner additive is buried in the running of a low image area, the toner fluidity is deteriorated and the toner has a high cohesion, so that the recycled toner conveying performance can be maintained without change.
Further, even when vibration is applied to the process cartridge 650 and the apparatus main body 500, the transfer residual toner T1 is not peeled off from the screw surface due to the shock, so that a large amount of recycled toner is produced by the rotation of the recycled toner conveying screw 542 immediately after the vibration. The (transfer residual toner T1) is not mixed into the developing device 600.

  On the other hand, if the wall surface 590a of the recycle toner transport path 590 has a difficult toner adhesion property, the transfer residual toner T1 adheres to the gap portion that cannot be contacted even if the recycle toner transport screw 542 is rotated inside the recycle toner transport path 590. -It does not stick and accumulate. Therefore, even when vibration is applied to the process cartridge 650 and the apparatus main body 500, the transfer residual toner T1 does not peel off from the wall surface due to the shock. Therefore, a large amount of recycled toner ( The transfer residual toner T1) does not enter the developing device 600.

Next, the developer adhesion property common to the first and second embodiments will be described.
The surface of the developer that hardly adheres to the following materials was applied to the developing device, the recycled toner conveying screw, and the recycle toner conveying path, and the degree of fixation over time after the following test was observed.
In the test according to the configuration of the first embodiment, 200k images with a low image area with little toner replacement were output in an environment of high temperature and high humidity (27 ° C./80% RH) in which developer sticking is likely to occur. The characteristics and application methods of the various developer difficult-to-adhere surfaces used are as follows.
The test according to the configuration of the second embodiment is a test for outputting 200k images of a low image area as a condition in which the toner is greatly deteriorated in an environment of high temperature and high humidity (27 ° C./80% RH) where the toner is likely to adhere. On the way, after removing the process cartridge unit in which the developing device 600 and the process cartridge 650 are integrated for every 50k sheets, disassembling and reassembling the unit assuming the developer replacement, and tilting the unit or giving vibration Then, the image was again set in the image forming apparatus main body, and then various basic images were output, and the degree of background contamination and toner removal was confirmed.

Comparative Example 1
PC (polycarbonate resin) + ABS resin: Resin used for the developing device itself used for evaluation. The case of the developing device, the screw, and the recycled toner transport screw and the recycle toner transport path (process cartridge case) constituting the developer recovery unit were molded by injection molding using this resin.
Comparative Example 2
Polycarbonate: A part used as a CTL layer (charge transport layer) of a photoreceptor for electrophotography was coated on each part by a dipping method.
Comparative Example 3
Nanoglass coating: A coating with a three-dimensionally crosslinked siloxane skeleton structure. Expresses high water and oil repellency. Each part was coated with a nano glass coat manufactured by Nano Glass Coat Japan by dipping.
Examples 1 and 2.
TOYAL LOTUS (registered trademark): A highly water-repellent sheet material with nano-sized fine irregularities on the surface. Made of Toyo Aluminum This sheet was attached to each part with an adhesive layer on the back.
Example 3 NeverWet (registered trademark): A highly water-repellent spray agent that forms a fine uneven coating film on the surface. Each part was spray coated with NeverWet made by RUST-OLEUM.
Example 4
Nanoimprint film: Nanoimprint is a technique in which a mold is pressed against an object such as a softened thermoplastic resin or glass, or a liquid UV curable resin. The shape obtained by nanoimprint is a shape obtained by inverting the unevenness of the mold, and the nanoimprint requires a mold processed with high accuracy. However, if one mold is made, there is a characteristic that nano-size processing can be realized basically by a simple process similar to press processing.
Nanoimprints are broadly classified into thermal nanoimprints and optical nanoimprints. In thermal nanoimprint, a mold is pressed against a resin softened by heating to be deformed, cooled to below the softening point and solidified, and the shape is transferred by removing the mold. On the other hand, in the optical nanoimprint, a mold is pressed against a liquid UV curable resin to fill a space between the mold and the substrate, the resin is cured by irradiating ultraviolet rays or the like, and the shape is transferred by removing the mold.

In this embodiment, for example, an adhesive layer is provided on the back surface of a nano-imprint film having a moth-eye structure having a pitch of about 200 nm and a height of about 150 nm made of a thermoplastic resin, and each part (screw, collection guide) of the developing device 600 and Then, it was affixed to the wall surface 590 a of the recycle toner conveyance path 590 of the developer recovery unit 700 and the surface 542 a of the recycled toner conveyance screw 542.
Note that the method of applying the nanoimprint to the developing device 600 is not limited to this, and the developing device mold itself uses a nano-sized fine shape processed with high precision, and a surface in contact with the developer. The fine shape may be transferred to the case resin or screw resin.

Table 1 shows the roughness of the surface from Comparative Example 1 to Example 4, the fixing of the developer over time in the test according to the configuration of the first embodiment, and the background stain and toner in the test according to the configuration of the second embodiment. Indicates the degree of drop. In Table 1, the degree of developer fixation after the test aging evaluation according to the configuration of the first embodiment and the evaluation of the degree of background stain and toner drop immediately after the test attachment / detachment according to the configuration of the second embodiment are given by , X in three stages. X is out of specification, ◎ and ○ are acceptable, and ◎ is better than ○ in terms of the degree of fixing of the image agent, background stain, and toner removal.
For the measurement of the surface roughness Ra with a contact-type surface roughness meter, SURFCOM1400D manufactured by Tokyo Seimitsu was used, and the measurement was performed with a measurement length and a cut-off value according to JIS B0601: '01.
To measure the surface roughness Ra by SPM, use a scanning probe microscope system SPA400 manufactured by Seiko Instruments Inc., scan 10 μm square in DFM (tapping mode), correct the tilt, and cut with a measurement length of 2 μm. Measurements were taken without off. This measurement image is shown in FIG. The reason for setting the measurement length to 2 μm is necessary and sufficient for considering the contact interface between the toner and the material in view of the fact that the toner particle size generally used in an electrophotographic image forming apparatus is 2 to 10 μm. This is because it was considered to be a long length. As a result, it is possible to measure the uneven shape in a fine area in contact with the toner. In addition, each measured value is an average value of what was measured 10 times at different measurement locations. FIG. 19 shows SPM observation results of the toner and various surfaces.

Table 1 shows the surface roughness Ra of each surface and the degree of fixation after durability.
As shown in Table 1, under the condition of the surface roughness Ra described in the present invention, a result that the developer fixation after the time evaluation was good was obtained. Further, the TOYAL LOTUS 1 shown in the first embodiment is partially fixed on an inclined surface such as the collection guide 57a described with reference to FIGS. 12 and 13 and the second conveyance path 592 of the recycle toner conveyance path 590 illustrated in FIG. It was observed.

FIG. 18 schematically shows the relationship between toner particles and surface roughness.
18A shows a state where new toner particles are on a smooth surface, FIG. 18B shows a state where deteriorated toner is on a fine uneven surface, and FIG. 18C shows a surface roughness Ra of 5 μm. FIG. In a portion where the developer flows on an inclined surface, such as the collection guide 57a shown in FIGS. 12 and 13, if there are irregularities of the size to which the toner particles are caught as shown in FIG. The toner stays and sticking occurs. Adhesion can be suppressed by applying a material having a surface roughness Ra measured by a contact-type surface roughness meter to a surface smaller than 5 μm. Further, even when a material having a regular fine uneven shape as in Example 4 shown in FIG. 18B was used, it was possible to prevent the deteriorated developer from sticking.
In addition, in the second conveyance path 592 which is an inclined surface constituting the recycled toner conveyance path 590, if there is unevenness of a size that causes toner particles to be caught as shown in FIG. 18C, the toner stays there. When the vibration is applied, the toner falls quickly from the second conveying path 592 and a large amount of recycled toner is supplied. By applying a material having a surface roughness Ra measured by a contact surface roughness meter of less than 5 μm to such an inclined portion, toner accumulation on the inclined surface can be suppressed. Moreover, even when a material having a regular fine uneven shape as in Example 4 shown in FIG. 18B was used, good results were obtained.

  Regarding the surface roughness Ra at a measurement length of 2 μm measured by SPM, it is considered that there is no theoretical upper limit as to the upper limit of the range having developer difficult adhesion characteristics. However, if the fine irregularities are too large (the state where Ra is large at a measurement length of 2 μm indicates that the amplitude in the depth direction of the irregularities increases), the actual problem is that the SPM probe is a rough surface of the material. The measured value does not represent true roughness because it cannot follow. The surface roughness Ra measured by SPM has application restrictions in JIS, and Ra is set to 1 to 30 nm. In this measurement method, the measurement length is fixed at 2 μm, which does not conform to JIS, but the problem that the probe cannot follow the roughness surface is common. Therefore, although the lower limit value of the surface roughness Ra at the measured measurement length of 2 μm was set to 25 nm, no upper limit value was provided.

  As shown in FIG. 18A, in general, new toner (initial toner) has irregularities because of the external additive on the surface, but the toner after the aging evaluation is deteriorated toner shown in FIG. 18B. However, due to the liberation and burying of the external additive, the surface irregularity is less than that of the initial toner, and the contact area with the surface of the counterpart member in contact with the toner is increased. That is, the contact area between the surface of the screw or the collection guide and the toner increases. For this reason, the adhesion between the deteriorated toner and the surface of the member is increased, and the developer tends to stay from the adhesion of the toner, and the developer is fixed. As a result of intensive studies by the present inventors, for example, even if a highly smooth material such as Comparative Example 2 or Comparative Example 3 is formed on the surface of a screw or collection guide as a member of a toner partner, after evaluation over time It became clear that the developer sticking could not be prevented.

  The SPM observation results of the toner and various surfaces shown in FIG. 19 show the surface shapes obtained by cutting out the SPM observation results of the various surfaces and the initial toner used in this example and the comparative example at 2 μm square. Comparative Example 1 has a large roughness but no fine unevenness. Comparative Examples 2 and 3 are very smooth over the entire area, whereas Example 1-4 according to the present invention has large fine unevenness. . It can be seen that the surface of the initial toner has many fine irregularities due to the additive, and there are irregularities close to those of the examples.

FIG. 20 shows the relationship between the adhesion force between the toner and various surfaces before and after the evaluation over time, and the surface roughness Ra measured by SPM. The adhesion force was measured using the centrifugal separation method described in Japanese Patent No. 3676046, and the toner after the endurance test described above was used as the post-endurance toner. As shown in FIG. 19, in the range of the surface roughness Ra according to the present invention, it was possible to maintain a low adhesive force even for deteriorated toner. Thus, by applying a surface having fine irregularities, the contact area between the toner and the member surface can be kept small even with a developer after durability, and a low adhesion can be maintained. As a result, the developer sticking after the endurance can be suppressed. This is the effect of the present invention.
Further, toner adhesion to the developer recovery unit 700 (recycled toner conveyance path 590) can be suppressed, and problems caused by a large amount of recycled toner being replenished to the developing device 600 immediately after the process cartridge 650 is attached / detached can be prevented. Can do.

  In this example, the results using a toner having a volume average particle size of 5.2 μm and an average circularity of 0.96 are shown. However, the contact at the contact interface between the surface having the surface roughness defined in the present invention and the toner is shown. The state is substantially the same even for toners having an average particle diameter of 2 to 10 μm, and thus can be applied to toners having these particle diameters. In the toners used in the present embodiment and examples, titanium oxide and silica are used as additives as fluidity improvers, but the additives are not limited thereto. As the additive, for example, an inorganic fine powder may be adhered or fixed to the toner surface. The average particle size of the inorganic fine powder is suitably 10 to 200 nm. When the particle size is smaller than 10 nm, it is difficult to produce an uneven surface having an effect on fluidity, and when the particle size is larger than 200 nm, the powder shape becomes rough, resulting in a problem of toner shape.

  Inorganic fine powders used in the present invention include Si, Ti, Al, Mg, Ca, Sr, Ba, In, Ga, Ni, Mn, W, Fe, Co, Zn, Cr, Mo, Cu, Ag, V, and Zr. And oxides and composite oxides. Of these, fine particles of silicon dioxide (silica), titanium dioxide (titania), and alumina are preferably used. Further, it is effective to subject the inorganic fine powder to a surface modification treatment with a hydrophobizing agent or the like.

As described above, the surface of the member that is disposed in the case of the developing device shown in the first embodiment and that contacts the developer in the case is a surface having a developer difficult adhesion property due to the uneven shape of the surface. Since it was set as the structure, sticking of the developer in the developing device over time can be suppressed. For this reason, even when the toner deteriorates over time, the occurrence of abnormal images can be reduced, and there is no need to peel off and remove the adherent when changing the developer, which increases the man-hours of the operator. This leads to a reduction in costs.
The developer remaining on the image carrier on which a visible image is formed by the developer supplied from the developing device shown in the second embodiment is collected by the cleaning device, and the developer collected by the cleaning device Is provided with a developer recovery section that returns the developer to the developing means, and the surface in contact with the developer in the developer recovery transport section is configured as a surface having developer difficult adhesion characteristics due to the uneven shape of the surface. Toner adhesion can be suppressed, and problems caused by recycle toner being supplied to the developing device can be prevented.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.
For example, in the second embodiment, the present invention is applied to a monochrome copying machine, but the application example of the present invention is not limited to a monochrome copying machine. For example, a plurality of image carriers that form toner images of a plurality of colors, an image carrier to which a toner image formed on the image carrier is transferred, an intermediate transfer belt that is also an intermediate transfer member, and an intermediate transfer The image forming apparatus includes an intermediate transfer member cleaning device that recovers the developer remaining on the belt, and a developer recovery unit that returns the developer recovered by the intermediate transfer member cleaning device to the developing unit. Embodiments may be applied.
Further, the image forming apparatus is not limited to a monochrome or color copier, but is included in a printer, a facsimile, a multi-function machine having a plurality of these functions, and the like.
The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

2,514 Cleaning device 4,508 Charging device 5 (Y, M, C, Bk), 150, 200, 600 Developing device 23g, 23h, a, b Opening portion, communicating portion 23a1, 23a2, 51, 151, 604 Developing Agent carrier 23b1 First developer conveying member 23b2 Second developer conveying member 23b3 Third developer conveying member 40 (Y, M, C, Bk) 401, 402, 650 Process cartridge 50, 160, 201 Case 54 Second developer conveying member (developer conveying member)
53 First developer transport member (developer transport member)
57 Shielding member 57a Collection guide (conveyance path)
58 Developer Collection Unit 59 Developer Supply Unit 90, 91 Surface with Developer Difficult Adhesive Property 542 Recycled Toner Transport Screw (Conveying Member)
542a Recycled toner conveying screw surface (conveying member surface)
590 Developer recovery part transport path 590a Wall surface 591 First transport path (developer recovery part transport path)
592 Second transport path (developer recovery section transport path)
593 Third transport path (developer recovery section transport path)
700 Developer recovery unit B1 First developer transport unit (developer recovery unit)
B2 Second developer transport section (developer supply section)
B3 Third developer transport section (developer transport section)
G Developer T1 (Transfer residual toner) Collected developer X1, X2 Two tangents Z area

JP 2007-101927 A JP 2007-140573 A

Claims (18)

In the developing device having a developer in the case,
The surface in contact with the developer in the case has a developer difficult adhesion property,
The developing device has a surface having the developer difficult adhesion property that exhibits the developer difficult adhesion due to the uneven shape of the surface. The developing device according to claim 1,
The developing device has a surface having a surface roughness Ra greater than 25 nm at a measurement length of 2 μm as measured with a scanning probe microscope. The developing device according to claim 2, wherein the surface having the developer difficult adhesion property is a developing device having a surface roughness Ra measured by a contact type surface roughness meter in accordance with JIS B0601: '01 smaller than 5 μm. In the developing device according to any one of claims 1 to 3,
The developing device has a regular uneven shape on a surface having the developer difficult adhesion property. The developing device according to any one of claims 1 to 4,
A developer transport member disposed in the case and transporting the developer;
A transport path for the developer transported by the developer transport member;
The developing device, wherein the surface having the developer difficult adhesion property is at least a surface of the developer transport member or a transport surface of the transport path. The developing device according to claim 5, wherein
Among the spaces configured by being shielded in the longitudinal direction in the case, a developer recovery unit that forms a space for recovering the developer from the developer carrier, and
A developer supply section for supplying a developer toward the developer carrier;
A communication portion for circulating and conveying the developer disposed at both longitudinal ends of the two spaces,
The developer transport member is a first developer transport member and a second developer transport member disposed in the developer recovery unit and the developer supply unit, respectively, and at least the first developer transport A developing device in which the surface of the member or the surface of the second developer conveying member has a developer difficult adhesion property. The developing device according to claim 5, wherein
A developer carrier provided in the case;
Among the spaces configured by being shielded in the longitudinal direction in the case, a developer recovery unit that forms a space for recovering the developer from the developer carrier, and
A developer supply section for supplying a developer toward the developer carrier;
A developer transport unit that transports the developer from the downstream of the developer recovery unit to the upstream of the developer supply unit;
A communication portion for circulating and transporting the developer disposed at both longitudinal ends of the three spaces;
The developer transport member includes a first developer transport member, a second developer transport member, and a third developer transport disposed in the developer recovery unit, the developer supply unit, and the developer transport unit, respectively. Is a member,
A developing device in which at least the surface of the first developer conveying member, the second developer conveying member, or the third developer conveying member has a developer difficult adhesion property. The developing device according to claim 5, wherein
Two developer containing portions formed by partitioning the case;
An opening for communicating the two developer storage portions;
The developer conveying members are a first developer conveying member and a second developer conveying member that are arranged in the two developer accommodating portions, respectively, and circulate and convey the developer in each developer accommodating portion,
A developing device in which at least a surface of the first developer conveying member or the second developer conveying member has a developer difficult adhesion property. The developing device according to claim 5, wherein
A developer carrier provided in the case;
Among the spaces configured by being shielded in the vertical direction in the case, a developer recovery section that is located above and forms a space for recovering the developer from the developer carrier,
A developer supply unit that is located in the lower part of the vertical direction and supplies the developer toward the developer carrier;
A first developer transport member and a second developer transport member respectively disposed in the developer recovery section and the developer supply section;
A shielding member having a communication part located at both ends in the longitudinal direction of the first and second developer transport parts and communicating the developer recovery part and the developer supply part;
The transport path is a collection guide that is provided in the shielding member and guides the developer detached from the developer carrier to the developer collection unit.
A developing device in which a surface of the collection guide has a developer difficult adhesion property. The developing device according to claim 9, wherein
Of the collection guide, a developing device in which the surface in the region of the two tangents directed downward in the direction of gravity of the outer diameter line of the first developer conveying member is not formed with a surface having a developer difficult adhesion property . The developing device according to claim 9 or 10,
The developing device, wherein the collection guide is a flat surface.   A process cartridge comprising the developing device according to claim 1 and at least one of an image carrier, a charging device, and a cleaning device for the carrier.   An image forming apparatus comprising the process cartridge according to claim 12.   An image forming apparatus comprising the developing device according to claim 1. Developer that collects the developer remaining on the image carrier on which a visible image is formed by the developer supplied from the developing device is recovered by the cleaning device, and returns the developer recovered by the cleaning device to the developing unit. Part
The surface in contact with the developer in the developer recovery unit has a developer adhesion property,
The image forming apparatus in which the surface having the developer difficult adhesion property exhibits the developer difficult adhesion due to the uneven shape of the surface. The image forming apparatus according to claim 15.
The surface having the developer difficult adhesion property is an image forming apparatus having a surface roughness Ra of more than 25 nm at a measurement length of 2 μm measured by a scanning probe microscope. The image forming apparatus according to claim 16, wherein the surface having the developer difficult adhesion property has a surface roughness Ra measured by a contact type surface roughness meter according to JIS B0601: '01 and smaller than 5 μm. The image forming apparatus according to any one of claims 15 to 17,
The developer recovery unit includes a transport member that transports the developer recovered by the cleaning device, and a transport member that includes the transport member and is connected to the cleaning device and the development device. An image forming apparatus having a path, wherein at least a surface of the transport member or a wall surface of the developer recovery section transport path has a developer difficult adhesion property.

Images