JP2010256429A - Developer-stirring and transporting member, and developing device and image-forming device which use the member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer-stirring and transporting member which simultaneously increases ability for transport a two-component developer in an axial direction and ability for stirring and mixing the developer, and to provide a developing device and an image-forming device which use the same. <P>SOLUTION: The developer-stirring and transporting member includes a multi-thread spiral blade 178 having a plurality of spiral blades 178a, 178b which are spirally wound around a common rotary shaft 178s; and a discontinuity section BP, which cuts off the multi-thread spiral blade 178 so that the multi-thread spiral blade 178 becomes discontinuous in the axial direction. In the discontinuity section BP, the upstream-side end sections 178au, 178bu and downstream-side end sections 178ad, 178bd of the multi-thread spiral blade 178 are arranged so that they are different in phase around the rotary shaft 178s. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developer stirring and conveying member, a developing device using the same, and an image forming apparatus.

  Conventionally, in an image forming apparatus using an electrophotographic method or an electrostatic recording method, a developing device that develops an electrostatic latent image formed on an electrostatic latent image holding member such as a photosensitive drum is used. As such a developing device, for example, a two-component developer comprising a magnetic carrier and a resin-based toner in a developing housing in which a developing opening is opened facing the electrostatic latent image holding member. And a developer holder (for example, a developing roll) is provided facing the developing opening of the developing housing, and the two-component developer in the developing housing is stirred and conveyed to the back side of the developing roll. 2. Description of the Related Art A so-called two-component developing type developing device in which an auger to be supplied to a developing roll is disposed is widely used (see, for example, Patent Documents 1 to 4).

  Here, Patent Documents 1 and 2 disclose a developer stirring and conveying member provided with multiple spiral blades (screws) over the entire length of the auger.

  Patent Documents 3 and 4 disclose a developer stirring and conveying member in which a deficient portion is provided in a part of the axial direction of a spiral blade.

JP 09-258535 A JP 2002-31940 A JP 07-333968 A Japanese Patent Laid-Open No. 08-286480

  An object of the present invention is to provide a developer agitating / conveying member capable of simultaneously increasing the axial conveying ability and the agitating and mixing ability of a two-component developer, a developing device using the same, and an image forming apparatus. It is.

  The developer stirring / conveying member according to claim 1, wherein the multi-strand spiral blade having a plurality of spiral blades spirally formed around a common rotation axis, and the multi-strand spiral blade are discontinuous in the axial direction. A discontinuous portion for dividing the multi-strand spiral blade so that the upstream end and the downstream end of the multi-strand spiral blade have different phases around the rotation axis. The arrangement is formed as described above.

  The developer agitating / conveying member according to claim 2 is the configuration according to claim 1, wherein the plurality of spiral blades constituting the multi-row spiral blade are attached and arranged around the rotation axis at equal phase intervals. In addition, the upstream end and the downstream end of the multiple spiral blade in the discontinuous portion are arranged to face each other at a phase interval substantially half of the equal phase interval. It is.

  The developer agitating / conveying member according to claim 3, in the configuration according to claim 2, wherein the multi-spindle spiral blade is composed of two spiral blades whose phases around the rotation axis are different by 180 °, and The upstream end and the downstream end of the two spiral blades facing each other across the discontinuous portion are arranged so that the phases around the rotation axis are different by about 90 °. Is.

  The developer stirring and conveying member according to claim 4 is the configuration according to any one of claims 1 to 3, wherein the upstream end and the downstream end of the spiral blade are opposed to each other with the discontinuous portion interposed therebetween. Is characterized by being arranged so as to overlap in the axial direction.

  The developer stirring and conveying member according to claim 5 is the configuration according to any one of claims 1 to 3, wherein the discontinuous portion includes flat plate blades protruding radially along the axial direction. In the vicinity of the downstream side of the plate blade, the number of the multi-row spiral blades is reduced.

  The developing device according to claim 6, a rotatable developer holding body for holding a developer on a surface thereof, a developer containing portion for containing the developer adjacent to the developer holding body, and the developer 6. The developer stirring and conveying member according to claim 1, wherein the developer stirring and conveying member is disposed in a housing portion and is stirred and conveyed in a predetermined axial direction so that the developer can be supplied to the developer holding member. And a developer replenishing port that is replenished with a new developer, and the discontinuous portion of the developer agitating and conveying member is provided downstream of the developer replenishing port. It is characterized by being.

  A developing device according to a seventh aspect of the present invention is the construction according to the sixth aspect, further comprising a toner concentration sensor that detects a toner concentration in the developer, wherein the discontinuous portion of the developer agitating and conveying member includes the toner concentration It is provided in the upstream of a sensor.

  An image forming apparatus according to an eighth aspect includes the developing device according to the sixth or seventh aspect and an image forming unit that forms an image on a recording sheet.

  According to the first aspect of the present invention, the developer conveying ability in the axial direction can be improved, and the stirring and mixing ability in the circumferential direction can be improved.

  According to the second aspect of the present invention, the uniform diversion / merging action of the two-component developer can be promoted, and the axial conveyance amount can be made uniform stably.

  According to the third aspect of the present invention, it is possible to easily realize the developer agitating and conveying member that contributes to the uniform diversion / merging action of the two-component developer and the uniform conveyance amount in the axial direction.

  According to the fourth aspect of the present invention, it is possible to guide the flow of the developer at the discontinuous portion, and to more smoothly perform the division and merging of the developer at the portion.

  According to the fifth aspect of the present invention, it is possible to smoothly transfer the two-component developer from the plate blade to the downstream spiral blade in the axial direction.

  According to the sixth aspect of the present invention, the circulating developer and the newly supplied developer can be rapidly stirred and mixed.

  According to the seventh aspect of the present invention, the toner concentration in the developer can be stably detected in a sufficiently stirred and mixed state.

  According to the eighth aspect of the present invention, any one of the developing devices can be suitably applied to an image forming apparatus.

1 is a configuration diagram showing a tandem type digital color copying machine as an example of an image forming apparatus to which the present invention is applicable. It is a typical sectional side view for demonstrating the structure of the image development apparatus which concerns on this Embodiment. It is a typical plane sectional view for explaining the composition of the development device concerning this embodiment. 3 is a schematic diagram for explaining a configuration of an admix auger according to Embodiment 1. FIG. It is a schematic diagram for demonstrating the structure of the admix auger which concerns on Embodiment 1, (a) is a schematic diagram which shows the rotation direction and angle area | region of an admix auger, (b) is the spiral blade along an axial direction It is a schematic diagram which shows a presence angle area | region. 6 is a schematic diagram for explaining the operation of the discontinuous portion of the admix auger according to Embodiment 1. FIG. 5 is a schematic diagram for explaining a configuration of an admix auger according to Embodiment 2. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a schematic configuration of an image forming apparatus to which the present invention can be applied will be described with reference to FIG. Here, FIG. 1 is a configuration diagram showing a tandem type digital color copying machine as an example of an image forming apparatus to which the present invention is applicable. Although this tandem type color electrophotographic copying machine is provided with an image reading device, the image forming device is not provided with an image reading device and is based on image data output from a personal computer (not shown) or the like. It may be a color printer, a facsimile, or the like that forms an image.

  In FIG. 1, reference numeral 1 denotes a main body of a tandem type digital color copying machine as an example of an image forming apparatus to which the present invention can be applied. In a state where originals 2 are separated one by one at the upper part of the main body 1. An automatic document conveying device 3 that automatically conveys and a document reading device 4 that reads an image of the document 2 conveyed by the automatic document conveying device 3 are provided. The document reader 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 from a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. The image reading element 11 made of a CCD or the like is scanned and exposed through a reduction optical system, and the image material 11 reflects the color material reflected light image of the original 2 by a predetermined dot density (for example, 16 dots / mm). ).

  The color material reflected light image of the document 2 read by the document reading device 4 is subjected to image processing, for example, as document reflectance data of three colors of red (R), green (G), and blue (B) (8 bits each). The image processing apparatus 12 sends images such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color / moving editing, etc. to the reflectance data of the document 2. Processing is performed. In addition, the image processing device 12 performs predetermined image processing on image data sent from a personal computer or the like.

  The image data that has been subjected to the predetermined image processing by the image processing device 12 as described above is processed by the image processing device 12 in the same manner as yellow (Y), magenta (M), cyan (C), and black (K). (8 bits each) is converted into four-color original reproduction color material gradation data, and as described below, image formation of each color of yellow (Y), magenta (M), cyan (C), and black (K) The images are sent to the exposure devices 14 of the units 13Y, 13M, 13C, and 13K, and the exposure device 14 performs image exposure with the laser beam LB in accordance with the original reproduction color material gradation data of each color.

  Inside the tandem digital color copying machine main body 1, four image forming units 13Y, 13M, 13C, and 13K of yellow (Y), magenta (M), cyan (C), and black (K) are horizontally arranged. They are arranged in parallel at regular intervals in the direction.

  These four image forming units 13Y, 13M, 13C, and 13K are all configured in the same manner, and are roughly divided into a photosensitive drum 15 as an image carrier that is rotationally driven at a predetermined speed, and the photosensitive drum. A charging roll 16 for primary charging that uniformly charges the surface of 15, and an exposure device 14 including a scanning optical system that exposes an image corresponding to each color on the surface of the photosensitive drum 15 to form an electrostatic latent image, and The image forming apparatus includes a developing device 17 that develops the electrostatic latent image formed on the photosensitive drum 15 with each color toner, and a drum cleaning device 18 that cleans the surface of the photosensitive drum 15.

  The exposure device 14 is configured in common to the four image forming units 13Y, 13M, 13C, and 13K, and modulates four semiconductor lasers (not shown) according to the original reproduction color material gradation data for each color, The laser beams LB-Y, LB-M, LB-C, and LB-K are emitted from the semiconductor laser according to the gradation data. Of course, the exposure apparatus 14 may be individually configured for each of a plurality of image forming units. The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the semiconductor laser are irradiated to the rotary polygon mirror 19 through an f-θ lens (not shown) and deflected by the rotary polygon mirror 19. Scanned. The laser beams LB-Y, LB-M, LB-C, and LB-K deflected and scanned by the rotary polygon mirror 19 are scanned and exposed from below on the photosensitive drum 15 through a plurality of reflection mirrors (not shown). Is done.

  The exposure apparatus 14 is hermetically sealed by a rectangular parallelepiped frame 20, and four laser beams LB-Y, LB-M, LB-C, and LB-K are placed on the upper portion of the frame 20. In order to perform exposure on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K, transparent glass windows 21Y, 21M, 21C, and 21K are provided as shield members. These glass windows 21Y, 21M, 21C, and 21K are members located at the uppermost position on the optical path along the laser beam LB of the exposure apparatus 14.

  From the image processing apparatus 12, an exposure apparatus 14 provided in common for the image forming units 13Y, 13M, 13C, and 13K for each color of yellow (Y), magenta (M), cyan (C), and black (K). In addition, the image data of each color is sequentially output, and the laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the exposure device 14 according to the image data are the surfaces of the corresponding photosensitive drums 15. And an electrostatic latent image is formed. The electrostatic latent images formed on the photosensitive drum 15 are respectively yellow (Y), magenta (M), cyan (C), and black (K) toners by developing devices 17Y, 17M, 17C, and 17K. Developed as an image.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K are as follows. On the intermediate transfer belt 25 disposed over the image forming units 13Y, 13M, 13C, and 13K, the images are transferred in multiple by the primary transfer roll 26. The intermediate transfer belt 25 is wound around the drive roll 27 and the backup roll 28 with a constant tension, and is driven by a drive roll 27 that is rotationally driven by a dedicated drive motor with excellent constant speed (not shown). The circuit is circulated at a predetermined speed in the direction of the arrow. As the intermediate transfer belt 25, for example, a flexible synthetic resin film such as PET is formed in a band shape, and both ends of the synthetic resin film formed in a band shape are connected by means such as welding, thereby endless A belt-shaped one is used.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred onto the intermediate transfer belt 25 in a multiple manner are transferred to the backup roll 28 by a secondary transfer roll 29. The recording paper P, which is secondarily transferred onto the recording paper P by the pressure contact force and electrostatic force, and onto which the toner images of these colors are transferred, is conveyed to the fixing device 30 positioned above. The secondary transfer roll 29 is in pressure contact with the side of the backup roll 28, and secondary-transfers each color toner image onto the recording paper P conveyed from below to above. The recording paper P on which the toner images of the respective colors are transferred is subjected to a fixing process with heat and pressure by the fixing device 30 and then discharged onto a discharge tray 33 provided on the upper portion of the main body 1 by a discharge roll 32. The

  The recording paper P having a predetermined size from the paper feed cassette 34 is once transported to a registration roll 38 via a paper transport path 37 by a paper feed roller 35 and a pair of rollers 36 for paper separation and transport. Stopped. The recording paper P supplied from the paper feed cassette 34 is sent to the secondary transfer position of the intermediate transfer belt 25 by a registration roll 38 that rotates at a predetermined timing.

  In the above-described digital color copying machine, when full-color double-sided copying is performed, the recording paper P with the image fixed on one side is not discharged onto the discharge tray 33 as it is by the discharge roll 32 but is switched not shown. The conveyance direction is switched by the gate, and the sheet is conveyed to the duplex conveyance unit 40 via the sheet conveyance roller pair 39. Then, in the double-sided conveyance unit 40, the recording paper P is conveyed again to the registration roll 38 with the front and back sides of the recording paper P reversed by a pair of conveyance rollers (not shown) provided along the conveyance path 41. Is discharged onto the discharge tray 33 after the image is transferred and fixed on the back surface of the recording paper P.

  The four image forming units 13Y, 13M, 13C, and 13K of yellow, magenta, cyan, and black are all configured in the same manner. In these four image forming units 13Y, 13M, 13C, and 13K, As described above, yellow, magenta, cyan, and black toner images are sequentially formed at predetermined timings. As described above, the image forming units 13Y, 13M, 13C, and 13K for the respective colors include the photosensitive drums 15, and the surfaces of these photosensitive drums 15 are uniformly charged by the charging roll 16 for primary charging. The Thereafter, the surface of the photosensitive drum 15 is scanned and exposed to an image forming laser beam LB emitted from the exposure device 14 according to the image data, and an electrostatic latent image corresponding to each color is formed. The laser beam LB scanned and exposed on the photosensitive drum 15 is set so as to be exposed at a predetermined inclination angle from an obliquely lower side slightly to the right side from directly below the photosensitive drum 15. The electrostatic latent images formed on the photosensitive drum 15 are respectively yellow, magenta, cyan, and black toners by the developing rolls 172 of the developing devices 17 of the image forming units 13Y, 13M, 13C, and 13K. Are developed into visible toner images, and these visible toner images are sequentially transferred onto the intermediate transfer belt 25 in multiple layers by charging of the primary transfer roll 26.

  Residual toner, paper dust, and the like are removed from the surface of the photosensitive drum 15 after the toner image transfer process by the drum cleaning device 18 to prepare for the next image forming process. The drum cleaning device 18 includes a cleaning blade (not shown), and the cleaning blade removes residual toner, paper dust, and the like on the photosensitive drum 15. Further, residual toner, paper dust, and the like are removed from the surface of the intermediate transfer belt 25 after the toner image transfer process is completed by the belt cleaning device 43 to prepare for the next image forming process. The belt cleaning device 43 includes a cleaning brush 43a and a cleaning blade 43b, and residual toner and paper dust on the intermediate transfer belt 25 are removed by the cleaning brush 43a and the blade 43b.

  In the present embodiment, above the intermediate transfer belt 25, yellow (Y), magenta (M), cyan (C), and black (K) developing devices 17 having predetermined colors are provided. Toner cartridges 50Y, 50M, 50C, and 50K for supplying developer (mainly toner or toner containing carrier) are disposed.

  Next, the configuration of the developing devices 17Y, 17M, 17C, and 17K according to the present embodiment will be described with reference to FIGS. Here, FIG. 2 is a schematic side sectional view showing the configuration of the developing device according to the present embodiment, and FIG. 3 is a schematic plan sectional view. The developing devices 17Y, 17M, 17C, and 17K and their constituent members have the same structure, and therefore, for the sake of simplicity, the symbols are hereinafter collectively referred to (for example, the developing device 17).

  The developing device 17 according to the present embodiment employs a so-called two-component developing system, and has a developing housing 171 that opens toward the photosensitive drum 15 as shown in FIGS. A developing roller 172 as a developer holding member is disposed facing the opening of the developing housing 171, and a first developer in which a two-component developer is accommodated in a portion of the developing housing 171 adjacent to the developing roller 172. A second developer container 173b that is adjacent to the container 173a and the first developer container 173a via the partition wall W and communicates with the first developer container 173a at both axial ends thereof. And.

  Each of the first developer accommodating portion 173a and the second developer accommodating portion 173b according to the present embodiment has a space for accommodating a two-component developer, and the first developer accommodating portion 173a includes a two-component developer. A spiral first developer agitating / conveying member 177 for conveying the developer in a predetermined axial direction (for example, from the right side to the left side in FIG. 3) is provided. On the other hand, in the second developer accommodating portion 173b, a spiral second development for conveying the two-component developer in the direction opposite to the first developer stirring and conveying member 177 (for example, from the left side to the right side in FIG. 3). An agent stirring and conveying member 178 is provided. A developer circulation path that circulates between the first developer accommodating portion 173a and the second developer accommodating portion 173b via communication ports C1 and C2 provided at both ends in the axial direction (longitudinal direction) of the partition wall W. The two-component developer in the developer circulation path is circulated and conveyed while being agitated and mixed by the pair of spiral first developer agitating and conveying members 177 and the second developer agitating and conveying member 178. Yes.

  Here, each of the first developer agitating / conveying member 177 and the second developer agitating / conveying member 178 has a spiral spiral blade integrally formed with the rotating shaft and is formed to be rotatable. The first developer stirring and conveying member 177 on the developing roll 172 side is a supply auger that has a function of supplying a developer to the developing roll 172 in addition to a function of stirring and mixing toner. On the other hand, the second developer agitating / conveying member 178 is an admix auger whose main purpose is to agitate and mix toner supplied to an existing two-component developer. The details of the admix auger 178 which is a developer stirring and conveying member according to the present embodiment will be described later.

  Further, a developer supply port T is opened on the upstream side of the second developer accommodating portion 173b, and a toner density sensor S is disposed on the downstream side. Further, a dispense auger (not shown) is disposed at a portion adjacent to the second developer accommodating portion 173b, and the toner concentration in the developer accommodating portions 173a and 173b by the developing action is larger than a predetermined range. In the case of lowering, the second developer storage portion 173b is provided with the first through the developer supply port T from the toner cartridge 50 via the dispense auger (not shown) based on the detection result of the toner density sensor S provided at the bottom on the downstream side. A new developer is supplied into the two developer accommodating portion 173b. In the present embodiment, the two-component developer is a developer composed of a toner and a magnetic carrier. For example, a non-magnetic toner is used as the toner. Can be used.

  In the present embodiment, the developing roll 172 includes a developing sleeve 172s that rotates in a predetermined direction (clockwise in this example) during development, and a magnet roll 172m that is fixed inside the developing sleeve 172s. It has.

  Here, the developing sleeve 172 s rotates in a predetermined direction, and is an opening of the developing housing 171 in a region facing the photosensitive drum 15 (hereinafter referred to as a developing region). Are arranged so as to face each other at a predetermined gap. Further, a developing bias power source (not shown) for forming a developing electric field between the developing sleeve 172s and the photosensitive drum 15 (developing region) is connected.

  Further, the magnet roll 172m as the magnetic field generating means is formed in a roll shape by arranging a plurality of magnet members in the circumferential direction, and includes a development magnetic pole S1 arranged corresponding to the development region, and a development roll 172. For example, a transport magnetic pole N1 and a pick-off magnetic pole S2 arranged at predetermined angular intervals are provided on the downstream side of the developing magnetic pole S1 along the rotation direction, and a predetermined angle is provided on the upstream side of the developing magnetic pole S1. Trimming magnetic poles N2 and pickup magnetic poles S3 arranged at intervals are provided. The magnetic roll 172m in which the magnetic poles are arranged in this manner causes the developing roll 172 to have a predetermined magnetic flux density distribution corresponding to the magnetic force of each magnetic pole. The arrangement and number of magnetic poles in the magnet roll 172m may be appropriately selected.

  In the present embodiment, a layer thickness regulating member 174 is disposed near the lower side of the trimming magnetic pole N2 in the developing roll 172 so as to face the developing roll 172 (trimming magnetic pole N2). The layer thickness regulating member 174 is a substantially square-shaped member extending along the axial direction of the developing roll 172, and is predetermined so as to regulate the amount of the two-component developer on the developing roll 172. The developing roller 172 is disposed close to the gap.

During development in which the developing roll 172 rotates in a predetermined direction (clockwise direction in this example), the two-component developer in the first developer accommodating portion 173a is agitated and conveyed by the supply auger 177, Captured by the pick-up magnetic pole S3 in the developing roll 172. Thereafter, the captured two-component developer is conveyed in the rotation direction of the developing roll 172 (developing sleeve 172s) by the magnetic attraction force of the pickup magnetic pole S3 and the frictional force between the surface of the developing roll 172, and the layer thickness regulating member When the vicinity of 174 is reached, a spike is formed by the trimming magnetic pole N2. The rising of the two-component developer is regulated by the layer thickness regulating member 174, so that it is formed on the developing roll 172 as a developer layer having a predetermined layer thickness and conveyed to the development area. Further, the developer layer of the two-component developer conveyed to the development area forms a magnetic brush by the magnetic attraction force of the developing magnetic pole S1, and the toner in the two-component developer forming the magnetic brush is a photosensitive drum. The electrostatic latent image on the photosensitive drum 15 is visualized by a developing electric field formed between the roller 15 and the developing roller 172. On the other hand, surplus toner that has passed through the developing region moves along with the rotation of the developing roll 172, and is returned to the first developer accommodating portion 173a again by the magnetic force of the pick-off magnetic pole S2. Further, according to the consumption of the two-component developer in such a developing operation, a new two-component developer is appropriately supplied from the second developer accommodating portion 173b to the first developer accommodating portion 173a, and the developing device 17 continuously operates. Is now possible.
<Embodiment 1>

  Next, the configuration of the developer agitating / conveying member (in this example, the admix auger) 178 according to the first embodiment will be described with reference to FIG. Here, FIG. 4 is a schematic diagram for explaining the configuration of the admix auger 178 according to the first embodiment.

  As schematically shown in FIG. 4, the admix auger 178 according to the present embodiment includes two spiral blades 178a (solid line portion in the drawing) and 178b (in the drawing) formed in a spiral shape around the rotation shaft 178s. In addition, the spiral blades 178a and 178b are discontinuous in the axial direction (the spiral blades 178a and 178b are missing) at a plurality of locations in the axial direction. A one-dot chain line portion) is provided. Note that the ridge lines of the actual spiral blades 178a and 178b have a substantially sinusoidal curved shape, but in this figure, they are approximately expressed in a straight line for simplicity.

  The spiral blades 178a and 178b are formed to have the same diameter and the same pitch, and are arranged so that the phases around the rotation shaft 178s are different from each other by 180 °.

  In this way, by providing multiple (in this example, 2) spiral blades 178a and 178b, the transport surface for transporting the two-component developer is more axial in comparison with the configuration in which a single spiral blade is provided. Since doubling is performed in a cross section perpendicular to the cross section, the conveying ability in the axial direction of the two-component developer can be increased.

  On the other hand, even when multiple (in this example, two) spiral blades 178a and 178b are provided, the stirring and mixing ability in the circumferential direction does not increase significantly, and the toner and the carrier are not sufficiently stirred. If the two-component developer is immediately conveyed in the axial direction and delivered to the supply auger 177, it may cause image defects such as density unevenness.

  Therefore, in the admix auger 178 according to this embodiment, the spiral blades 178a and 178b are provided with the following discontinuous portions BP, and simultaneously with the increase in the axial conveyance capacity by the multi-row spiral blades 178a and 178b. The stirring and mixing function can be increased.

  Next, the configuration and operation of the discontinuous portion BP in the admix auger 178 according to the present embodiment will be further described with reference to FIGS. Here, FIG. 5A is a schematic diagram showing the rotation direction and angle region of the admix auger 178, and FIG. 5B is a schematic diagram showing the existence angle region of the spiral blades along the axial direction. is there. FIG. 6 is a schematic diagram for explaining the operation of the discontinuous portion BP.

  As schematically shown in FIG. 5A, the rotation direction of the spiral blades 178a and 178b according to the present embodiment is set in the counterclockwise direction as viewed from AA in FIG. The existence areas of 178a and 178b are set as shown in FIG. Here, the horizontal axis in FIG. 5B indicates the position in the axial direction, and the vertical axis in FIG. 5B indicates the spiral blades 178a and 178b when the angle region is set as shown in FIG. 5A. The existence angle region of is shown. Of the two spiral blades 178a and 178b, the solid line in FIG. 5B indicates one spiral blade 178a, and the dotted line indicates the other spiral blade 178b having a 180 ° mounting phase different from that of the spiral blade 178a. .

  As best shown in FIG. 5B, the discontinuous portion BP (in this example, four locations X (4), X (8), X (12), and X (16) in the figure). , The upstream end portions 178au and 178bu and the downstream end portions 178ad and 178bd of the spiral blades 178a and 178b facing each other across the discontinuous portion BP are 90 ° out of phase with each other (so as to be shifted by 90 °). Is arranged. For example, in the discontinuous portion BP (4) in X (4), the upstream end 178au of the spiral blade 178a is disposed at a position of 180 °, whereas the downstream end 178ad is 90 °. It is arranged so as to be at a position of °, and the mounting phase difference between them is set to be 90 °. Further, the upstream end 178bu of the spiral blade 178b is arranged to exist at a position of 0 ° (360 °), whereas the downstream end 178ad is arranged to be at a position of 270 °. The mounting phase difference between them is set to 90 °. Similarly, in the other discontinuous portions BP (8), BP (12), and BP (16), the upstream end portions 178au and 178bu and the downstream sides of the spiral blades 178a and 178b facing each other with the discontinuous portion BP interposed therebetween. The end portions 178ad and 178bd are set and arranged so that the attachment phase differs by 90 °.

  That is, the admix auger 178 according to the present embodiment includes two spiral blades 178a and 178b having different 180 ° phases, and ends of the opposing spiral blades 178a and 178b in the discontinuous portion BP. Are arranged so that their phases differ by 90 °.

In the admix auger 178 according to the present embodiment configured as described above, the flow Ga of the two-component developer conveyed mainly by the conveying surface of the spiral blade 178a is discontinuous as schematically shown in FIG. It is conveyed to the upstream end 178au of the part BP and guided to the downstream end 178ad that is 90 ° out of phase with the upstream end 178au and is divided into _two flows Ga ₁ and Ga ₂ (divided) ) On the other hand, the flow Gb of the two-component developer transported by the spiral blade 178b having a transport surface 180 degrees behind (or advanced from) the transport surface of the spiral blade 178a is arranged in a phase different from the spiral blade 178a by 180 °. The upstream end portion 178bu of the discontinuous portion BP is conveyed to the downstream end portion 178bd facing the upstream end portion 178bu with a phase difference of 90 ° and guided to the two flows Gb ₁ and Gb ₂ . Divided (divided).

That is, as schematically shown in FIG. 6, the boundary of the discontinuity portion BP, the upstream side of the spiral blade 178a, the two-component developer Ga conveyed by 178b, Gb, at discontinuities BP, Ga _1, while being split into two portions of the flow of Ga ₂ and Gb _1, Gb _2, the flow Ga ₁ diverted, Ga _2, Gb _1, Gb _2, the phase of the end portion are arranged differently 90 ° The downstream spiral blades 178a and 178b merge into another two new flows (specifically, two flows of Ga ₂ + Gb ₁ and Ga ₁ + Gb ₂ ). The stirring and mixing of the two-component developer in the circumferential direction is promoted.

  Here, by providing the discontinuous portion BP in any one of the axial directions, it is possible to obtain the above-described stirring and mixing action by the diversion / merging of the two-component developer. From the viewpoint of repeatedly promoting the stirring and mixing of the two-component developer, it is preferable to provide a plurality of stages in the axial direction (provided at a plurality of positions in the axial direction).

  In addition, when viewed from the discontinuous portion BP, the upstream end portions 178au and 178bu of the spiral blades 178a and 178b and the corresponding downstream end portions 178ad and 178bd are arranged to overlap (overlap) in the axial direction. It is preferable (see FIG. 6). In this way, by disposing the end portions (upstream end portions 178au, 178bu and downstream end portions 178ad, 178bd) facing each other on the upstream side and the downstream side of the discontinuous portion BP so as to overlap in the axial direction. Such an end portion serves as a guide, and the diversion / merging action in the discontinuous portion BP is promoted, so that the two-component developer can be stirred and mixed more smoothly.

Further, from the viewpoint of dividing the upstream flows Ga and Gb evenly as viewed from the discontinuous portion BP and then merging them to facilitate smooth flow in the axial direction, the opposing ends 178au and 178bu. , 178ad, 178bd, the mounting phase difference (90 ° in this example) should be set to be approximately half of the mounting phase difference (2 ° in this example) of the spiral blades 178a, 178b (180 ° in this example). Is preferred. As a result, the downstream end portions 178ad and 178bd are disposed at a substantially middle position between the upstream end portions 178au and 178bu, and the two-component developer flows Ga and Gb are divided approximately evenly (Ga ₁ , Ga ₂ and Gb ₁ , Gb ₂ ) and then merging them again (Ga ₂ + Gb ₁ and Ga ₁ + Gb ₂ ), so that the axial conveyance amount can be made uniform and stable. It should be noted that the number of spiral blades constituting the multi-spindle spiral blade 178 may be arbitrarily set. For example, when the spiral blades are composed of three spiral blades 178a, 178b, 178c, each spiral blade 178a, 178b. , 178c is set to 120 °, and the mounting phase difference between the upstream end portions 178au, 178bu, 178cu and the downstream end portions 178ad, 178bd, 178cd facing each other at the discontinuous portion BP is set to 60 °. By setting to 1, it is possible to further increase the axial conveyance capacity and the stirring and mixing capacity of the two-component developer, and to contribute to further stabilization of the conveyance amount.

  Further, the discontinuous portion BP can be set at any location and the number of discontinuous portions BP. However, from the viewpoint of effectively preventing uneven mixing of the two-component developer, the discontinuous portion BP includes a new toner. Is preferably provided on the downstream side of the developer replenishing port T, which is likely to cause mixing unevenness.

Further, from the viewpoint of detecting a stable toner density after sufficiently stirring and mixing the two-component developer, the discontinuous portion BP is preferably provided on the upstream side of the toner density sensor S.
<Embodiment 2>

  Next, the configuration of the admix auger 178A according to Embodiment 2 will be described with reference to FIG. Note that the admix auger 178A according to the present embodiment is provided with a plate blade for stirring in a part of the axial direction as compared with the previous embodiment, and the configuration of the spiral blade on the downstream side of the plate blade is changed. The members having the same functions as those of the previous embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As schematically shown in FIG. 7, the admix auger 178A according to the present embodiment has a discontinuous portion BP at an axial position corresponding to the installation location of the toner density sensor S (see FIGS. 2 and 3). Is formed. Further, the discontinuous portion BP is provided with a flat plate blade 178p protruding in the radial direction along the axial direction. Specifically, in FIG. 7, X (8) to X (12) are formed as discontinuous portions BP, and flat plate blades 178p are disposed over the axial direction region of the discontinuous portions BP. Has been.

  By providing such a plate blade 178p, the two-component developer can be stably supplied to the detection surface of the toner concentration sensor S, which can contribute to stabilization of toner concentration detection.

  By the way, in the multi-striped spiral blades 178a and 178b as described above, when such a plate blade 178p is provided, the occupied sectional area of the spiral blade is increased on the downstream side of the plate blade 178p as compared to the single spiral blade. Since the cross-sectional area in which the two-component developer can pass in the axial direction is narrowed, there is a possibility that the two-component developer may be hindered in the smooth conveyance in the axial direction.

  Therefore, in the admix auger 178 according to the present embodiment, the number of spiral blades 178b on the downstream side of the plate blade 178p is reduced.

  Specifically, as shown in the axial direction region X (12) to X (16) in FIG. 7, in the region immediately downstream of the plate blade 178p, the number of spiral blades 178 is set to one (this example). Then, only the spiral blade 178a is used. In other words, the region where the spiral blade 178b exists on the downstream side of the plate blade 178p extending over X (8) to X (12) is set as the axial region downstream of X (16).

  As a result, the occupied sectional area of the spiral blade immediately after the downstream side of the plate blade 178p is decreased, and the inflow amount (axial transport amount) of the two-component developer to the spiral blade formation region after passing through the plate blade 178p is increased. Thus, the two-component developer can be smoothly transferred from the plate blade 178p to the spiral blade 178a in the axial direction.

  According to the developer agitating / conveying member 178 according to the present invention configured as described above, the discontinuous portions in which the opposite end portions 178au, 178ad and 178bu, 178bd are shifted in phase between the multiple spiral blades 178a, 178b. By providing BP, it is possible to simultaneously increase the axial conveyance capability and the agitation mixing capability of the two-component developer by the diversion / merging action in the discontinuous portion BP.

  Further, by reducing the number of multi-spiral spiral blades 178 immediately downstream of the stirring plate blade 178p provided in the discontinuous portion BP, excessive retention of the two-component developer in the discontinuous portion BP is obviated. Can be prevented.

  The technical scope of the present invention is not limited to the above-described embodiments, and various modifications or improvements can be added without departing from the scope of the present invention described in the claims. is there. For example, in each of the above-described embodiments, the configuration in which the multiple spiral blades having the discontinuous portion BP are applied to the admix auger 178 is illustrated, but the axial conveyance capability is increased and the stirring and mixing performance is improved. Of course, the present invention may be applied to the supply auger 177 or may be applied to other members (for example, a dispense auger in the toner replenishment path) that stirs and conveys the developer. Moreover, although each embodiment mentioned above may each be implemented independently, naturally, you may implement it combining suitably.

1: Image forming apparatus, 13Y, 13M, 13C, 13K: Image forming unit, 14: Exposure apparatus, 15Y, 15M, 15C, 15K: Photosensitive drum, 16Y, 16M, 16C, 16K: Charging roll, 17Y, 17M, 17C , 17K: Development device, 18Y, 18M, 18C, 18K: Drum cleaning device, 25: Intermediate transfer belt, 26Y, 26M, 26C, 26K: Primary transfer roll, 29: Secondary transfer roll, 30: Fixing device, 34: Paper feed cassette, 38: Registration roll, 40: Double-sided conveyance unit, 43: Belt cleaning device, 50Y, 50M, 50C, 50K: Toner cartridge, 171: Development housing, 172: Development roll, 172m: Magnet roll, 172s: Development sleeve, 173a: first developer container, 173b: second Image agent accommodating portion, 174: layer thickness regulating member, 177: supply auger, 178, 178A: admix auger, 178a, 178b: spiral blade, 178au, 178bu: upstream end, 178ad, 178bd: downstream end, 178P: leaf blade, 178S: rotary shaft, BP: discontinuity, C1, C2: communicating _{port, Ga, Gb, Ga 1,} Ga 2, Gb 1, Gb 2: two-component developer, P: recording sheet, S : Toner density sensor, T: Developer supply port, W: Partition wall

Claims (8)

A multi-row spiral blade having a plurality of spiral blades spirally wound around a common rotation axis;
A discontinuous portion for dividing the multi-strand spiral blade so that the multi-strand spiral blade is discontinuous in the axial direction;
In the discontinuous portion, the developer agitating / conveying member, wherein the upstream end portion and the downstream end portion of the multi-strand spiral blade are arranged and formed to have different phases around the rotation axis.   The plurality of spiral blades constituting the multi-row spiral blade are attached and arranged at equal phase intervals around the rotation axis, and the upstream end and the downstream end of the multi-row spiral blade in the discontinuous portion 2. The developer agitation transport unit according to claim 1, wherein the developer agitation transport unit is opposed to the unit at a phase interval substantially half of the equal phase interval.   The multi-spindle spiral blade is composed of two spiral blades whose phases around the rotation axis are 180 ° different from each other, and is opposite to the upstream end of the two spiral blades and is opposed to the discontinuous portion. The developer agitating / conveying member according to claim 2, wherein the side end portion is disposed so that a phase around the rotation axis is different by about 90 °.   The upstream end and the downstream end of the spiral blade that face each other across the discontinuous portion are arranged so as to overlap in the axial direction. A developer agitating and conveying member according to 1.   The discontinuous portion is provided with flat plate blades that protrude in the radial direction along the axial direction. In the vicinity of the downstream side of the plate blades, the number of the multi-row spiral blades decreases. The developer agitating / conveying member according to claim 1, wherein the developer agitating / conveying member is provided. A rotatable developer holder that holds the developer on its surface;
A developer accommodating portion for accommodating a developer adjacent to the developer holder;
6. The developer agitation according to claim 1, wherein the developer agitation is arranged in the developer accommodating portion and agitated and conveyed in a predetermined axial direction so that the developer can be supplied to the developer holding member. A conveying member;
A developer replenishing port which is opened in the developer accommodating section and is replenished with a new developer;
The developing device, wherein the discontinuous portion of the developer agitating / conveying member is provided downstream of the developer supply port. A toner concentration sensor for detecting the toner concentration in the developer;
The developing device according to claim 6, wherein the discontinuous portion of the developer agitating and conveying member is provided on the upstream side of the toner density sensor.   8. An image forming apparatus comprising: the developing device according to claim 6; and an image forming unit that forms an image on a recording sheet.

Images