JP2020034786A - Developer device - Google Patents

Abstract

To provide a developer device having a configuration capable of suppressing streaks from being generated on the developer layer on the surface of the developing roller.SOLUTION: A first conveying member 43a conveys the developer from the developing container to a developing roller by rotating. The first conveying member 43a has a rotating shaft 43aa, a rotating member 43ab, and an inclined member 430. The rotating member 43ab is arranged substantially parallel to the rotating shaft 43aa at a predetermined distance from the rotating shaft 43aa, and rotates together with the rotating shaft 43aa. A plurality of inclined members 430 is arranged on the rotating shaft 43aa to be inclined with respect to the rotating shaft 43aa, and rotates together with the rotating shaft 43aa.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a developing device that develops an electrostatic latent image formed on an image carrier such as a photosensitive drum.

  2. Description of the Related Art An image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction peripheral having a plurality of these functions develops, for example, an electrostatic latent image on a photosensitive drum using a developing device using toner. As such a developing device, a developer carrier, a layer thickness regulating member for regulating a layer thickness of the developer carried on the developer carrier, and a developer are stirred and the developer is directed toward the developer carrier. There has been proposed a configuration including a transport member that transports the paper (for example, Patent Document 1).

JP-A-2-269377

  In the case of the configuration described in Patent Document 1, the developer is transported by the transport member in a direction substantially perpendicular to the rotation axis direction of the developer carrier. For this reason, the movement of the developer in a direction substantially parallel to the rotation axis direction of the developer carrier is small.

  Here, the layer thickness of the developer carried on the developer carrying member is regulated by the layer thickness regulating member. At this time, the developer receives a force such as a large shearing force. For this reason, as described above, with the configuration in which the movement of the developer in the direction substantially parallel to the rotation axis of the developer carrier is small, when the image is formed for a long time, When the external additive for imparting the toner is embedded in the matrix of the toner particles, the fluidity of the toner may be reduced. When the toner fluidity is reduced, a portion of the layer between the layer thickness regulating member and the surface of the developer carrying member is clogged with toner aggregates, and the layer thickness is regulated downstream of the surface of the developer carrying member. Streaks may occur in the developer layer, and image quality may be degraded.

  An object of the present invention is to provide a configuration capable of suppressing generation of streaks in a developer layer on the surface of a developer carrying member.

  The developing device of the present invention is a developing device that develops an electrostatic latent image on an image carrier with a developer, and a developer container that stores the developer, and rotates the developer in the developer container. A developer carrying member that carries and conveys the developer; a layer thickness regulating member that regulates a layer thickness of the developer carried by the developer carrying member; A transport member for transporting the carrier to the carrier, the transport member includes a rotating shaft, a rotating member disposed substantially parallel to the rotating shaft at a predetermined distance from the rotating shaft, and rotating with the rotating shaft, And a plurality of inclined members which are arranged on the rotating shaft, are inclined with respect to the rotating shaft, and rotate together with the rotating shaft.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of a streak in the developer layer of the surface of a developer carrying body can be suppressed.

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment. FIG. 1 is a schematic sectional view of a configuration of a developing device according to a first embodiment. FIG. 3 is a plan view of a second transport member according to the first embodiment. FIG. 6 is a schematic plan view of a developing device according to Comparative Example 1. FIG. 9 is a schematic diagram showing a state in which streaks have occurred on a developing roller in Comparative Example 1. FIG. 2 is a cross-sectional view of a first transport member according to the first embodiment. FIG. 2A is a perspective view of the inclined member according to the first embodiment, and FIG. FIG. 2A is a plan view of the inclined member according to the first embodiment viewed from a rotation axis direction, and FIG. FIG. 5 is a schematic cross-sectional view of a configuration of a developing device according to a second embodiment. FIG. 9 is a schematic plan view of a developing device according to a third embodiment.

<First embodiment>
The first embodiment will be described with reference to FIGS. First, a schematic configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG.

[Image forming apparatus]
The image forming apparatus 100 is an electrophotographic monochrome printer. The image forming apparatus 100 includes a toner (document reading apparatus) connected to the image forming apparatus main body, or a toner based on an image signal from an external terminal such as a personal computer (PC) communicably connected to the image forming apparatus main body. An image is formed on the recording material m. Examples of the recording material include sheet materials such as paper, plastic film, and cloth.

  The image forming apparatus 100 of the present embodiment includes a cylindrical photosensitive member, that is, a photosensitive drum 2 as an image carrier that is driven to rotate in the direction of arrow D2. In this embodiment, the photosensitive drum 2 includes a photosensitive layer containing amorphous silicon as a main component, and has an outer diameter of 80 mm. Around the photosensitive drum 2, a charging device 3, a developing device 4, a pre-transfer charging device 5, a transfer roller 6, a cleaning device 8, a static elimination exposure lamp 9, and the like are arranged along a direction of an arrow D <b> 2. An exposure apparatus 1 is disposed above the exposure apparatus 2. Further, a fixing device 11 is disposed downstream of the transfer roller 6 with respect to the transport direction Dm of the recording material m.

  The charging device 3 as a charging unit is, for example, a corona charger including two charging lines and 14 grid lines. The transfer roller 6 as a transfer unit is a sponge roller having a conductive rubber sponge layer around a cored bar. The cleaning device 8 as a cleaning unit is configured by a rubber plate member (rubber blade) or the like. As the photosensitive drum 2 rotates, the rubber blade slides on the surface of the photosensitive drum 2 and the toner on the photosensitive drum 2 It is configured so that it can be cleaned.

  The fixing device 11 includes a fixing roller 111, and a pressure roller 112 that contacts the fixing roller 111 to form a fixing nip. The fixing roller 111 has a built-in halogen heater 113 serving as a heat source, and its outer surface is maintained at a predetermined temperature by the halogen heater 113.

  Next, an image forming operation of the image forming apparatus 100 configured as described above will be described. The photosensitive drum 2 is rotationally driven by an unillustrated motor in the direction of arrow D2 at an outer peripheral speed of, for example, 400 mm / s. The surface of the photosensitive drum 2 is reduced to, for example, +500 V (surface potential Vd) by the charging device 3 to which the primary charging bias is applied. Likewise charged. Then, the surface of the photosensitive drum 2 is irradiated with exposure light L corresponding to an image signal to be output from the exposure device 1, and the irradiated surface of the photosensitive drum 2 is set to, for example, +120 V (the potential Vl of the exposure unit). As a result, an electrostatic latent image is formed.

  The image forming apparatus 100 of the present embodiment employs a background part exposure method instead of a general image part exposure method in a digital image forming apparatus, so that a non-exposed part is visualized. Then, the toner (-) charged to the opposite polarity to the charge polarity (+) of the photosensitive drum 2 by the developing device 4 is attached to the electrostatic latent image to be visualized as a toner image. Note that the image portion may be exposed to visualize the image. Thereafter, the toner image on the photosensitive drum 2 is further charged by the pre-transfer charging device 5 and reaches a transfer nip formed by the photosensitive drum 2 and the transfer roller 6.

  Next, at a predetermined timing, the recording material m waiting on the registration roller pair 13 is conveyed to the transfer nip portion. Then, by applying a transfer current to the transfer roller 6 at this position, the toner image is transferred from the photosensitive drum 2 to the recording material m. The recording material m on which the toner image has been transferred is transported to the fixing device 11 by a transport device (not shown).

  The recording material m is transported to a fixing nip formed by the fixing roller 111 and the pressure roller 112. Then, the toner image is heated and pressed in the fixing nip portion, and the toner image is fixed on the recording material m. When an image is formed on one side of the recording material m, the image is discharged from the fixing device 11 and then discharged outside the apparatus as it is. When an image is formed on both surfaces of the recording material m, the image is reversed by a reversing device (not shown). Then, an image is formed on the opposite surface of the recording material m in the same manner as described above.

  On the other hand, the toner remaining on the surface of the photosensitive drum 2 after the transfer is removed and collected by the cleaning device 8, and further, the surface of the photosensitive drum 2 is discharged by the discharge lamp 9 to prepare for the next image forming operation. In the case of the image forming apparatus 100 of the present embodiment, for example, the continuous output speed to one side in the case of the plain paper A4 side (when the recording material m is transported so that the longitudinal direction of the plain paper is orthogonal to the transport direction Dm). Is, for example, 80 pages / minute.

[Developing device]
Next, the developing device 4 of the present embodiment will be described with reference to FIG. The developing device 4 includes a developing container 40, a developing roller 41, a regulating blade 42, a first conveying member 43a, a second conveying member 43b, a toner detection sensor 44, and the like. The developing container 40 contains a developer containing a toner. In the present embodiment, the developer is a so-called one-component developer that includes a toner having magnetic properties (magnetic toner) and does not include a carrier.

  The developing roller 41 as a developer carrier is disposed in an opening formed in a portion of the developing container 40 facing the photosensitive drum 2. The developing roller 41 is, for example, a cylindrical member having an outer diameter of 32.3 mm, and has a permanent magnet 41a disposed therein. Then, it is rotationally driven in the direction of the arrow by a motor (not shown). The developing roller 41 is opposed to the photosensitive drum 2 with a gap of about 250 μm when the resin rollers provided at both ends contact the both ends of the photosensitive drum 2. In the present embodiment, the developing roller 41 is formed by applying a conductive coating having a thickness of about 15 μm made of a material mainly composed of phenol resin to the surface of a cylindrical member made of an aluminum alloy having a thickness of 0.7 mm. The initial surface roughness was about 0.85 μm Ra by surface polishing or the like.

  The regulating blade 42 serving as a layer thickness regulating member is disposed upstream of the developing roller 41 in the rotation direction of a region where the developing roller 41 faces the photosensitive drum 2, and is disposed such that a gap between the developing roller 41 and the developing roller 41 is about 230 μm. I have. Such a regulating blade 42 is a plate-shaped magnetic metal blade. For example, the regulating blade 42 has a plate shape having a thickness of 1 mm, a length of 340 mm, and a width of 30 mm. The size of the gap between the opposing portions P between the regulating blade 42 and the developing roller 41 is 230 μm.

  The first transport member 43a and the second transport member 43b are each made of resin and formed in a ladder shape, are arranged in the developing container so that their rotation axes are substantially parallel, and the toner in the developing container 40 is provided. Is transported to the developing roller 41 while being stirred. The first transport member 43a and the second transport member 43b are arranged such that the rotation axis is substantially parallel to the rotation axis of the developing roller 41. For example, the toner supplied from the toner bottle (not shown) into the developing container 40 via the hopper 7 (FIG. 1) causes the first transport member 43a and the second transport member 43b to rotate in the directions of arrows D43a and D43b, respectively. Is conveyed in the direction of the developing roller 41.

  That is, when the second transport member 43b as another transport member rotates, the toner in the developing container is transported in a direction intersecting the rotation direction. The first transport member 43a as a transport member is disposed downstream in the developer transport direction by the second transport member 43b, and further transports the developer transported from the second transport member 43b to the developing roller 41. That is, the first transport member 43a is arranged at a position closer to the developing roller 41 than the second transport member 43b, and supplies the developer to the developing roller 41. In other words, the first transporting member 43b is a transporting member arranged at a position closest to the developing roller 41 among a plurality of transporting members for transporting the developer in the developing container 40.

  As shown in FIG. 3, the second transport member 43 b includes a rotating shaft 43 ba at both ends and a rotating member 43 bb that is disposed substantially parallel to the rotating shaft 43 ba at a predetermined distance from the rotating shaft 43 ba and rotates together with the rotating shaft 43 ba. Have. The rotating shaft 43ba is connected by connecting portions 43bc at portions near both ends of the rotating member 43bb, and the second transport member 43b is formed in a substantially crank shape. The detailed configuration of the first transport member 43a will be described later.

  The toner detection sensor 44 as a toner detection unit is a sensor of a magnetic permeability detection type disposed at a predetermined height position in the developing container 40, and detects toner when the toner in the developing container 40 reaches a predetermined height. I do. Thus, the toner amount M in the developing container 40 in the stable state is maintained at a predetermined amount (about 400 g in the present embodiment). That is, by supplying toner from the hopper 7 into the developing container 40 based on the signal of the toner detection sensor 401, the toner in the developing container 40 is maintained at a predetermined amount.

  The toner conveyed to the developing roller 41 by the first conveying member 43a and the second conveying member 43b is carried on the surface of the developing roller 41 by the magnetic attraction of the permanent magnet 41a built in the developing roller 41. The developing roller 41 is conveyed to a portion P facing the regulating blade 42 by rotating in the direction of arrow D41, for example, at an outer peripheral speed of 520 mm / s. The toner carried on the developing roller 41 at the facing portion P is regulated in layer thickness by the action of the magnetic force between the magnetic pole of the permanent magnet 41a and the regulating blade 42, and is conveyed to the facing portion with the photosensitive drum 2. .

  A developing bias is applied to the developing roller 41 from a power supply 49. The toner on the developing roller 41 conveyed to the portion facing the photosensitive drum 2 is transferred to the photosensitive drum 2 by the action of an electric field formed at the portion facing the developing roller 41 and the photosensitive drum 2 by the developing bias. As a result, the electrostatic latent image formed on the photosensitive drum 2 (on the image carrier) is developed by the toner and is visualized. At this time, the toner not subjected to the development is collected on the developing roller 41. The developing bias is an oscillating voltage obtained by superimposing an AC voltage on a DC voltage. In the present embodiment, the developing bias is a rectangular wave having an amplitude of 1300 V, a frequency of 2700 Hz, and an average potential of +410 to 320 V.

[Comparative example]
Here, Comparative Example 1 will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic configuration plan view of the developing device 4A of Comparative Example 1. In the case of Comparative Example 1, the first transporting member 43Aa for transporting the developer in the developing container 40 has the same configuration as the second transporting member 43b shown in FIG. 3, and other configurations are the same as those of the above-described embodiment. And the same as

  In the case of such a configuration, the first transport member 43Aa transports the developer toward the developing roller 41 in a direction B substantially perpendicular to the rotational axis direction of the developing roller 41. The movement of the developer in a substantially parallel direction is small.

  Here, the developer supplied from the first transport member 43Aa to the developing roller 41 is carried by the developing roller 41, and the thickness of the layer is regulated by the regulating blade. At this time, a developer pool in which the developer is densely formed is formed around the developing roller 41 and in a space adjacent to the upstream side of the regulating blade 42. When an image is formed over a long period of time, the developer is subjected to a force such as a shearing force in the developer reservoir. Property is apt to decrease.

  In particular, in the case of the configuration of Comparative Example 1, since the movement of the developer in a direction substantially parallel to the rotation axis direction of the developing roller 41 is small, the fluidity of the toner is likely to decrease, and the toner aggregates are accumulated in the developer pool. Easy to occur. Then, as shown in FIG. 5, a part of the space between the regulating blade 42 and the surface of the developing roller 41 is clogged with the toner aggregates tb, and the layer thickness is regulated downstream of the surface of the developing roller 41. Streaks T may occur in the agent layer, and the image quality may be degraded.

[First transport member]
Therefore, in the present embodiment, the first transport member 43a disposed adjacent to the developing roller 41 is configured as follows. The first transport member 43a will be described with reference to FIGS. 6 to 8B. As shown in FIG. 6, the first transport member 43a includes a rotating shaft 43aa, a rotating member 43ab, and an inclined member 430.

  The rotating shaft 43aa is different from the rotating shaft 43ba (FIG. 3) of the second transport member 43b and is a single continuous shaft from one end to the other end. The rotating member 43ab is disposed substantially parallel to the rotating shaft 43aa at a predetermined distance from the rotating shaft 43aa, and rotates together with the rotating shaft 43aa. The rotating shaft 43aa and the rotating member 43ab are connected by connecting portions 43ac at portions near both ends of the rotating shaft 43aa. The rotating shaft 43aa and the rotating member 43ab have a circular cross section with a diameter of 2 mm, for example, and are made of resin.

The configuration of the first transport member 43a except for the rotation shaft 43aa between the inclined member 430 and the connecting portions 43ac on both sides is the same as that of the second transport member 43b. The radius of the rotation area of the first transport member 43a and the second transport member 43b is, for example, 16 mm, and the rotation speed is 0.42 (s ^-1 ).

  The plurality of inclined members 430 are arranged on the rotating shaft 43aa (on the rotating shaft), are inclined with respect to the rotating shaft 43aa, and rotate together with the rotating shaft 43aa. The plurality of inclined members 430 are arranged at substantially equal intervals on the rotating shaft 43aa between the connecting portions 43ac on both sides. Note that some or all of the intervals in the rotation axis direction of the plurality of inclined members 430 may be different from each other. Further, the plurality of inclined members 430 are arranged so as not to contact the rotating member 43ab. As shown in FIGS. 7A and 7B, the outer shape of a portion of the inclined member 430 inclined with respect to the rotation axis 43aa is substantially elliptical.

  The inclined member 430 is made of resin and includes a hollow elliptical portion 431 that is inclined with respect to the rotating shaft 43aa and has an elliptical outer shape, and a connecting portion 432 that connects the elliptical portion 431 and the rotating shaft 43aa. Is done. The connecting portion 432 has a cylindrical portion 432a externally fitted and fixed to the rotating shaft 43aa, and a column portion 432b connecting the cylindrical portion 432a and the elliptical portion 431. The column portions 432b extend from two locations on the outer peripheral surface of the cylindrical portion 432a so as to be inclined with respect to the central axis (coaxial with the rotation axis 43aa) of the cylindrical portion 432a, and are connected to the inner peripheral surface of the elliptical portion 431. Such pillars 432b are arranged one by one at a position 180 ° out of phase on the outer periphery of the cylindrical part 432a. The number and position of the pillars 432b can be set arbitrarily.

  Further, as shown in FIG. 8B, the angle θ formed between the elliptical portion 431 and the cylindrical portion 432a is 45 ± 1 °. For this reason, when the inclined member 430 is viewed from the center axis direction of the cylindrical portion 432a, it becomes as shown in FIG. 8A, and the elliptical portion 431 has a substantially circular shape. Further, as shown in FIG. 6, the inclination members 430 have the same inclination direction and inclination angle with respect to the rotation shaft 43aa.

  Note that the inclination angles of the plurality of inclination members 430 with respect to the rotation shaft 43aa may be different from each other. Alternatively, the inclination angles of some of the plurality of inclined members 430 may be the same, and the inclination angles of one or more of the other inclined members 430 may be different from the inclination angles of some of the plurality of inclined members 430. For example, the inclination angles of the plurality of inclination members 430 may be alternately changed. The same applies to the inclination direction and the size of the elliptical portion 431.

  Further, the phases around the rotation axis 43aa of the elliptical portions 431 of the plurality of inclined members 430 are the same in the present embodiment, but may be different from each other. Alternatively, the phase of some of the plurality of inclined members 430 may be the same, and the phase of one or more of the other inclined members 430 may be different from the phase of some of the plurality of inclined members 430. For example, the phases of the plurality of inclined members 430 may be alternately changed. Specifically, the phase of the major diameter portion of the elliptical portion 431 may be alternately changed by 45 ° or 90 °.

  In the case of the present embodiment, since the first transport member 43a has a plurality of inclined members 430, when the developer is transported from the first transport member 43a to the developing roller 41, as shown in FIG. The developer reciprocates in the direction C along the rotation axis 43aa. That is, the developer is conveyed from the first conveying member 43 a toward the developing roller 41 while moving along the rotation axis direction of the developing roller 41.

  For this reason, due to the movement of the developer, the aggregates of the toner in the developer reservoir are disintegrated and dispersed, or the aggregates of the toner are less likely to be generated in the developer reservoir. In addition, it is possible to prevent the toner aggregate from clogging a part between the regulating blade 42 and the surface of the developing roller 41. As a result, it is possible to suppress the occurrence of the streak T in the developer layer of which the layer thickness is regulated on the downstream side of the surface of the developing roller 41, and it is possible to suppress a decrease in image quality.

[Experiment]
An experiment performed to confirm the effect of the present embodiment will be described. In the experiment, image formation was performed under the same conditions in Comparative Example 1 described above and Example 1 having the configuration of the present embodiment described above, and the performance of each was examined. In the experiment, 100,000 pages were output on an A4-size landscape paper at an intermittent pace of 20 pages / min. Examined. As the performance, "image vertical streak T index" and "in-plane image density variation" were examined.

  "Image vertical streak T index" was calculated by the following procedure. First, a uniform halftone image (A3 size) with an image ratio of 50% output on one side by the image forming apparatus according to the present embodiment was scanned by a multifunction printer “imageRUNNER ADVANCE (trademark) C5235” manufactured by Canon Inc. The scanning conditions are: image type: gray scale, resolution: 600 × 600 dpi, output image format: jpeg, document type: photograph, density correction: −1. Then, from the scanned image, the luminance data output by the known image analysis software is binarized, and the ratio of the sum of the region lengths of the higher numerical values to the A3 size width is defined as “image vertical streak T index”. . An image vertical streak T index of 0 means that the image vertical streak (streak T shown in FIG. 5) cannot be recognized (that is, the image quality is good), and if it is 7.5% or more, the image quality is acceptable. Means you can't.

  The “in-plane image density variation” is a difference between the highest value and the lowest value of the image reflection density in a uniform halftone image (A3 size) having an image ratio of 50% and output on one side by the image forming apparatus according to the present embodiment. It is. The image reflection density is a value measured by a 504 type densitometer manufactured by X-Rite, USA.

The experimental results are shown in Table 1.

  In Comparative Example 1 in Table 1, the number of transport members having the inclined member is 0 because the first transport member 43Aa does not have the inclined member. On the other hand, in the first embodiment, since the first transport member 43a has the inclined member 430, the number of transport members having the inclined member is one. Note that Comparative Examples 2 and 3 and Examples 2 and 3 will be described later.

  As is clear from Table 1, in Example 1 having the configuration of the present embodiment, both the “image vertical streak T index” and the “in-plane image density variation” were favorable numerical values compared to Comparative Example 1. . For this reason, according to the present embodiment, it was found that the generation of the streak T was suppressed, and good image quality was obtained.

<Second embodiment>
A second embodiment will be described with reference to FIG. Although the developing device 4 of the first embodiment has one developing roller 41, the developing device 4B of the present embodiment has a plurality of developing rollers. In the present embodiment, a third transport member 43c as a transport member is provided in addition to the first transport member 43a and the second transport member 43b. Other configurations and operations are the same as those of the above-described first embodiment. Therefore, the same components are denoted by the same reference numerals, and the description thereof is omitted or simplified. Will be described.

  The developing device 4B has a developing container 40 containing a magnetic toner as a developer. A first developing roller 410 and a second developing roller 411 as a plurality of developer carriers are arranged close to each other at an opening of the developing container 40 facing the photosensitive drum 2. The regulating blade 42 is disposed on the first developing roller 410 via a predetermined gap. The second developing roller 411 is disposed downstream of the first developing roller 410 in the rotation direction of the photosensitive drum 2 with a gap between the second developing roller 411 and the first developing roller 410. The gap between the closest part between the first developing roller 410 and the second developing roller 411 is 420 μm.

  The configuration of the first developing roller 410 and the second developing roller 411 is the same as that of the developing roller 41 of the first embodiment. The outer diameters of the first developing roller 410 and the second developing roller 411 are both 20 mm. is there. The photosensitive drum 2 rotates in the direction of arrow D2, and the first developing roller 410 and the second developing roller 411 rotate in directions of arrows D41a and D41b, respectively.

  The developer in the developing container 40 is conveyed to the vicinity of the second developing roller 411 by the rotating first ladder-shaped first conveying member 43a and the second conveying member 43b, and further, with the rotation of the second developing roller 411. The sheet is sent to the vicinity of a portion closest to the developing roller 410. When the developer carried on the second developing roller 411 passes through the closest part, its layer thickness is regulated by the first developing roller 410, and a developer layer is formed on the surface of the second developing roller 411. You. A part of the developer layer is subjected to development by the action of an electric field formed by a development bias at a portion facing the photosensitive drum 2, but the developer not subjected to development is stored in the developing container 40. Collected.

  On the other hand, of the developer transported to the vicinity of the closest portion between the second developing roller 411 and the first developing roller 410, the developer not carried on the surface of the second developing roller 411 is the first developing roller 410 Is transported to the vicinity of the regulating blade 42 with the rotation of. When the developer carried on the first developing roller 410 passes through the portion P facing the regulating blade 42, its layer thickness is regulated by the regulating blade 42, and the developer layer is formed on the surface of the first developing roller 410. It is formed. A part of this developer layer is also subjected to development at a portion facing the photosensitive drum 2, but the developer not subjected to development is sent to a portion closest to the second developing roller 411. A part of the developer sent to the nearest part is collected in the developing container 40, and the rest is transferred to the second developing roller 411 to become a part of the developer layer on the second developing roller 411.

  The developing device 4B includes three conveying members for conveying the developer in the developing container 40, and two of the first conveying member 43a and the third conveying member 43c are provided in FIGS. 6 to 8B. This is a transport member provided with the plurality of inclined members 430 described in (1). On the other hand, the second transport member 43b is a transport member having the crank shape shown in FIG. That is, the configuration and arrangement of the first transport member 43a and the second transport member 43b are substantially the same as those in the first embodiment described above, and the first transport member 43a is disposed adjacent to the second developing roller 411. ing.

  On the other hand, the third transport member 43c is disposed above the first transport member 43a and adjacent to the first developing roller 410. That is, the first transport member 43a and the third transport member 43c are arranged adjacent to the second developing roller 411 and the first developing roller 410, respectively.

  The first transport member 43a has a rotation area radius of 13 mm, and is arranged such that the gap at the closest point to the first developing roller 410 is 5 mm and the gap at the closest point to the second developing roller 411 is 4 mm. ing. Like the first embodiment, such a first transport member 43a includes a plurality of inclined members 430, so that the inside of the developer reservoir in a region Z2 surrounded by the first developing roller 410 and the second developing roller 411 is provided. Has a function of disintegrating and dispersing the toner aggregates.

  The third conveying member 43c has a rotation area radius of 7 mm, and is arranged such that a gap at the time of closest contact with the first developing roller 410 is 2 mm. Like the first transport member 43a, such a third transport member 43c includes a plurality of inclined members 430, so that the toner in the developer pool in the area Z1 surrounded by the first developing roller 410 and the regulating blade 42 is provided. Has the function of disintegrating and dispersing aggregates of

  As described above, in the case of the present embodiment, since the first transport member 43a and the third transport member 43c have the plurality of inclined members 430, the aggregates of the toner in the developer pools in the regions Z1 and Z2 are broken and dispersed. Easy to do. Alternatively, an aggregate of toner is less likely to be generated in the developer reservoir. For this reason, toner aggregates are formed on a part between the regulating blade 42 and the surface of the first developing roller 410 and on a part between the surface of the first developing roller 410 and the surface of the second developing roller 411. Clogging can be suppressed. As a result, it is possible to suppress the occurrence of the streak T in the developer layer whose layer thickness is regulated on the downstream side of the surfaces of the first developing roller 410 and the second developing roller 411, and it is possible to suppress the deterioration of image quality.

[Experiment]
In the present embodiment, an experiment was performed as in the first embodiment. In the experiment, image formation was performed under the same conditions in Example 2 having the configuration of the present embodiment described above and Comparative Example 2, and the performance of each was examined. Experimental conditions and the like are as described in the first embodiment. Further, in Comparative Example 2, the configuration of the first to third transport members for transporting the developer inside the developer container in the configuration of the above-described second embodiment is entirely the second transport member 43b shown in FIG. This has the same configuration as that of FIG. Note that the size and arrangement of the first to third transport members are substantially the same as those of the present embodiment. The results of this experiment are shown in Table 1 above.

  In Comparative Example 2 in Table 1, since the first to third transport members have no inclined members, the number of transport members having inclined members is zero. On the other hand, in the second embodiment, since the first transport member 43a and the third transport member 43c have the inclined members 430, the number of the transport members having the inclined members is two.

  As is clear from Table 1, in Example 2 having the configuration of the present embodiment, both the “image vertical streak T index” and the “in-plane image density variation” were favorable numerical values compared to Comparative Example 2. . For this reason, according to the present embodiment, it was found that the generation of the streak T was suppressed, and good image quality was obtained.

<Third embodiment>
A third embodiment will be described with reference to FIG. In each of the above embodiments, the configuration using the magnetic toner as the developer has been described. On the other hand, in the present embodiment, a so-called two-component developer including a non-magnetic toner and a magnetic carrier is used as the developer. Other configurations and operations are the same as those of the first embodiment, and therefore, the following description will focus on those parts that differ from the first embodiment.

  The developing device 4C of the present embodiment includes a developing container 40, a developing roller 41C, a regulating blade 42C, a first conveying member 43a, a second conveying member 43Cb, a toner density sensor 46, and the like. The developing container 40 contains a two-component developer containing a non-magnetic toner and a magnetic carrier.

  The developing roller 41C as a developer carrier is disposed in an opening formed in a portion of the developing container 40 facing the photosensitive drum 2. The developing roller 41C has a plurality of grooves each having a depth of 0.15 mm and a width of 0.4 mm and having a cross section of a substantially isosceles triangle extending in the longitudinal direction and having a uniform cross section in the circumferential direction at the outer surface thereof (72 in this embodiment). This is a cylindrical member made of an aluminum alloy. The developing roller 41C is opposed to the photosensitive drum 2 with a gap of about 420 μm. The developing roller 41C has a permanent magnet disposed inside, and is driven to rotate by a motor (not shown).

  The regulating blade 42C as a layer thickness regulating member is disposed in a region where the developing roller 41C faces the photosensitive drum 2 in the rotation direction upstream of the developing roller 41C, and is arranged such that a gap with the developing roller 41C is about 400 μm. I have. Such a regulating blade 42C is a plate-shaped non-magnetic metal blade. For example, the regulating blade 42C has a plate-like shape with a thickness of 0.5 mm, a length of 340 mm, and a width of 10 mm.

  The first transport member 43a and the second transport member 43Cb are each formed of a resin and formed in a ladder shape, are arranged in the developing container so that their rotation axes are substantially parallel to each other. The agent is conveyed to the developing roller 41C while stirring. The first transport member 43a and the second transport member 43Cb are arranged such that the rotation axis is substantially parallel to the rotation axis of the developing roller 41C. In the present embodiment, each of the first transport member 43a and the second transport member 43Cb has a plurality of inclined members 430, similarly to the first transport member 43a of the first embodiment.

The rotation area radius of the first transport member 43a and the second transport member 43Cb is 16 mm, and the first transport member 43a is disposed so that the gap at the time of closest contact with the developing roller 41C is 5 mm. The rotation speed of the first transport member 43a and the second transport member 43Cb is 7.9 (S ^-1 ).

  For example, the developer supplied from a toner bottle (not shown) into the developing container 40 via a hopper is transported in the direction of the developing roller 41C by the rotation of the first transport member 43a and the second transport member 43Cb. . At this time, the developer in the developing container 40 moves in the B direction while reciprocating in the C direction by the first transport member 43a and the second transport member 43Cb.

  In the case of a general developing device for a two-component developer, the two transport members are, for example, screws that transport the developer along the rotation axis direction, and a partition is provided between them to circulate the developer. Like that. On the other hand, in the present embodiment, since the developer in the developing container 40 moves in the direction B as described above, such a partition is not provided.

  The developer transported to the developing roller 41C is carried on the developing roller 41C. Then, the electrostatic latent image formed on the photosensitive drum 2 is developed by the toner of the developer carried on the developing roller 41C. When the toner concentration (the ratio of the mass of the toner in the developer) Ct of the developer in the developing container 40 decreases due to the development of the electrostatic latent image on the photosensitive drum 2, the Ct is reduced to a target value (6 to 12%). To this end, the amount of toner supplied from a toner bottle (not shown) is controlled.

  To this end, a toner concentration sensor 46 for detecting the toner concentration of the developer inside the developing container 40 is provided at the inner bottom of the developing container 40. The toner density sensor 46 is, for example, a sensor of a magnetic permeability detection type. A toner bottle (not shown) contains a replenishing developer (Ct = 80% to 100%). The developer supplied from the toner bottle is supplied to the developing device 4C via the hopper.

  In the case of the present embodiment, since the first transport member 43a has the plurality of inclined members 430, the first transport member 43a sets the toner in the developer pool in a region surrounded by the developing roller 41C and the regulating blade 42. It has the function of disintegrating and dispersing aggregates. Alternatively, an aggregate of toner is less likely to be generated in the developer reservoir. For this reason, similarly to the first embodiment, it is possible to suppress the toner aggregate from clogging a portion between the regulating blade 42C and the surface of the developing roller 41C. As a result, it is possible to suppress the occurrence of the streak T in the developer layer of which the layer thickness is regulated on the downstream side of the surface of the developing roller 41C, and it is possible to suppress the deterioration of the image quality.

  Further, in the case of the present embodiment, unlike a general developing device using a two-component developer, the first transport member 43a and the second transport member 43Cb that transport the developer in the developer container are not screw-shaped, but are formed as described above. The configuration is such that a plurality of inclined members are combined in a crank shape as shown in FIG. For this reason, component costs can be reduced as compared with a configuration in which the transport member is a screw-shaped member.

[Experiment]
In the present embodiment, an experiment was performed as in the first embodiment. In the experiment, image formation was performed under the same conditions in Example 3 having the configuration of the present embodiment described above and Comparative Example 3, and the performance of each was examined. Experimental conditions and the like are as described in the first embodiment. Comparative Example 3 has the same configuration as that of the third embodiment described above, except that the first and second transport members that transport the developer in the developer container have the same configuration as the second transport member 43b shown in FIG. This has the same configuration as that of FIG. The size and arrangement of the first and second transport members are almost the same as those of the present embodiment. The results of this experiment are shown in Table 1 above.

  In Comparative Example 3 in Table 1, since the first and second transport members do not have the inclined members, the number of the transport members having the inclined members is zero. On the other hand, in the third embodiment, since the first transport member 43a and the second transport member 43Cb have the inclined members 430, the number of the transport members having the inclined members is two.

  As is clear from Table 1, in Example 3 having the configuration of the present embodiment, both the “image vertical streak T index” and the “in-plane image density variation” were favorable numerical values compared to Comparative Example 3. . For this reason, according to the present embodiment, it was found that the generation of the streak T was suppressed, and good image quality was obtained.

<Other embodiments>
In each of the above-described embodiments, the case where the outer shape of the portion that is inclined with respect to the rotation axis of the plurality of inclined members is substantially elliptical is described. Other shapes such as a rectangular shape may be used. However, this portion is preferably plate-shaped, and more preferably hollow.

  Further, in the above-described first and second embodiments, the second transport member 43b is the crank-shaped transport member shown in FIG. 3, but this second transport member is also shown in FIGS. 6 to 8B. The transfer member having the inclined member shown in FIG.

  2 photosensitive drum (image carrier) / 4, 4B, 4C developing device / 40 developing container / 41, 41C developing roller (developer carrier) / 42 regulation Blade (layer thickness regulating member) / 43a ... first transport member (transport member) / 43aa ... rotary shaft / 43ab ... rotary member / 43b ... second transport member (another transport member) / 43Cb 2nd conveying member (conveying member) / 43c 3rd conveying member (conveying member) / 410 ... 1st developing roller (developer carrier) / 411 ... 2nd developing roller ( (Developer carrier) / 430 ... inclined member / 431 ... elliptical part / 432 ... connecting part / 432a ... cylindrical part / 432b ... column part

Claims (9)

A developing device for developing the electrostatic latent image on the image carrier with a developer,
A developing container for storing the developer,
By rotating, a developer carrier that carries and transports the developer in the developer container,
A layer thickness regulating member that regulates the layer thickness of the developer carried on the developer carrier,
By rotating, a transport member that transports the developer in the developer container to the developer carrier,
The transport member includes a rotating shaft, a rotating member disposed substantially parallel to the rotating shaft at a predetermined distance from the rotating shaft, and rotating together with the rotating shaft, and a plurality of rotating members disposed on the rotating shaft. And an inclined member that is inclined with respect to the rotation axis and rotates together with the rotation axis.
A developing device, characterized in that: The outer shape of the portion of the inclined member that is inclined with respect to the rotation axis is substantially elliptical.
The developing device according to claim 1, wherein: The inclined member is configured to include a hollow elliptical portion that is inclined with respect to the rotation axis and has an elliptical outer shape, and a connection portion that connects the ellipse portion and the rotation shaft.
The developing device according to claim 2, wherein: The connection portion has a cylindrical portion externally fitted and fixed to the rotation shaft, and a pillar portion connecting the cylindrical portion and the elliptical portion,
The developing device according to claim 3, wherein: The plurality of inclined members have the same inclination direction and inclination angle with respect to the rotation axis,
The developing device according to claim 1, wherein: By rotating, provided with another transport member that transports the developer in the developer container in a direction intersecting the rotation direction,
The transport member is disposed at a position closer to the developer carrier than the another transport member, and supplies developer to the developer carrier.
The developing device according to any one of claims 1 to 5, wherein: A plurality of the conveying members are arranged;
The developing device according to claim 1, wherein: The developer carrier is arranged in a plurality,
The plurality of transport members are respectively arranged adjacent to the developer carrier,
The developing device according to claim 7, wherein: The developer contains a magnetic toner,
The developing device according to any one of claims 1 to 8, wherein:

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