JP2006023355A - Development device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development device having new configuration capable of imparting prescribed electrification amount to toner and forming a high-quality image without decreasing conveying speed of developer in spite of simple constitution, and to provide an image forming apparatus. <P>SOLUTION: The development device has configuration for circularly conveying the developer by means of a 1st stirring member, a 2nd stirring member and a 3rd stirring member provided to be opposed to a part of the 1st stirring member, and configuration for sinking toner supplied to a part where the 1st and the 3rd stirring members are opposed through a toner supply port provided on the cover of a housing in the developer through the rotation of the 1st and the 3rd stirring members rotated so that their periphery may move from above to below. The image forming apparatus is equipped with the development device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device for developing an electrostatic charge latent image (hereinafter simply referred to as a latent image) formed on an image carrier as a toner image, and an image forming apparatus including the developing device.

  The surface of the image carrier is uniformly charged by a charging unit, and an exposure unit is operated based on a document or image data to form a latent image on the image carrier, and then a toner and a carrier. After the component developer is guided to the development area and the latent image is converted into a toner image by contact or non-contact development, the toner image is transferred onto a transfer material made of paper, for example, by a transfer unit, and a fixing unit 2. Description of the Related Art Image forming apparatuses that use an electrophotographic system that is fixed to the transfer material by heating and pressurizing using a toner are well known.

  In addition, a developer carrying member made of a rotatable cylindrical member, a position-fixed magnet built in the developer carrying member, and a two-component developer are agitated to give a charge amount necessary for development processing. The developing device is configured with the stirring member as a main element, and during the development processing, the stirred two-component developer adsorbed by the action of the magnet is carried on the peripheral surface of the developer carrying member, and the developer carrying member Also known is a developing device configured to sequentially convey the developer to the developing region by rotating the motor.

  In such a developing method using a two-component developer, a new amount of toner corresponding to the amount of toner consumed by image formation is appropriately replenished in the developing device, and the toner concentration in the developer is kept constant. Control to maintain the level is performed.

  Further, in the image forming apparatus as described above, there is a demand for higher image quality, and in response to such a demand, for example, the toner and carrier have a smaller particle size.

  Thus, a two-component developer mainly composed of a toner having a small particle size and a carrier having a small particle size is useful for achieving high image quality, but the fluidity of the developer itself is reduced. Therefore, it becomes difficult to sufficiently stir the developer.

  As a result, if the newly replenished toner is supplied to the development area without having a predetermined charge amount, the image quality is deteriorated due to fogging, and toner scattering is likely to occur. There's a problem.

  Such inconvenience particularly occurs when, for example, a color image having a high printing rate is continuously output.

  On the other hand, in recent years, many of the above-described image forming apparatuses generally have a configuration in which toner recycling means is provided and toner is recycled from the viewpoint of environmental conservation or resource saving. Since the toner (recycled toner) collected from the image carrier once subjected to development is inferior to unused toner in charging characteristics, problems such as fogging and toner scattering due to insufficient toner charge amount. There is a problem of being invited.

  In order to cope with such a problem, a technique for improving the stirring efficiency of the developer has been proposed.

For example, the developer carrying member, the first agitation transport member, and the second agitation transport member are arranged in this order and in the horizontal direction with the longitudinal direction aligned, and the first agitation transport member and the second agitation transport member are arranged. The developer is configured to be able to circulate and move with a partition wall provided between the conveying member and the length of both agitating and conveying members at least longer than one end of the developer carrying member. None, and in the projected area, the direction of the agitating member on the same axis is set so that the developer is agitated and conveyed in the direction opposite to the developer conveying direction by the respective agitating and conveying members. There has been proposed a configuration in which the agent is circulated so that toner is supplied to the agitating / conveying portion having at least one agitating / conveying member in the region (see, for example, Patent Document 1).
JP 20026631 (paragraph numbers 0033 to 0044, FIG. 3)

  However, the developing device disclosed in the above-mentioned patent document develops in two portions, that is, a stirring transport unit corresponding to a region facing the developer carrier and a stirring transport unit in a protruding region in one stirring transport unit. Since the construction is such that the agent is circulated, the developing device becomes larger and the construction of the apparatus becomes complicated.

  Even if the developer agitation efficiency can be improved by the above-described configuration, the developer circulating and conveying speed in the developing device is reduced. For example, it is used for an image forming apparatus having a high process speed. It seems that there is still room for improvement as a developing device.

  In other words, when the circulating conveyance speed of the developer decreases, the toner concentration of the developer supplied to the developer carrier becomes non-uniform in the direction of the rotation axis of the developer carrier, and in particular, an image with a high printing rate is displayed. In the case of continuous output, image density unevenness tends to occur, and it becomes difficult to form a high-quality image.

  In this way, if the replenished new toner can obtain a sufficient charge amount in a short time, the developer agitation ability is increased to prevent the occurrence of fog and toner scattering, resulting in a decrease in developer conveyance ability. As a result, it is difficult to solve the two conflicting problems at the same time.

  The present invention has been made in view of the above-described problems, and the main object is to provide a predetermined charge amount to the toner without reducing the developer conveyance speed while having a simple configuration. An object of the present invention is to provide a developing device and an image forming apparatus having a novel configuration capable of forming a high-quality image.

The object of the present invention can be achieved by the following constitution.
(Claim 1)
A developer carrier that carries and conveys a developer including toner and a carrier; and a side that is close to the developer carrier and adjacent to the longitudinal direction of the developer carrier, and the developer is disposed in a predetermined direction. A first agitating member that agitates while being conveyed, and a side far from the developer carrying member, adjacent to the longitudinal direction of the first agitating member, and the developer by the first agitating member A second stirring member that stirs the developer while transporting the developer in a direction opposite to the transport direction, and a housing that rotatably supports the developer carrier, the first stirring member, and the second stirring member. A developing device comprising a cover provided on an upper portion of the housing and configured to circulate and convey the developer by the first stirring member and the second stirring member;
A configuration in which the first stirring member and the second stirring member are extended to a side corresponding to the upstream side in the developer transport direction by the second stirring member and protrude from an end portion of the developer carrier. And
The first stirring member is provided in the protruding region and has a developer transport capability lower than that of the second stirring member, and the developer is in the same direction as the developer transport direction by the second stirring member. And a stirring portion 1B that has substantially the same developer transport capability as the second stirring member and that transports the developer in a direction opposite to the developer transport direction by the second stirring member. In addition,
The third stirring member has a higher developer transport capability than the second stirring member and stirs while transporting the developer in the direction opposite to the transport direction of the second stirring member. While being disposed facing the part 1A,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
A toner supply port for supplying toner is provided on the cover in a region corresponding to the upstream side when the stirring portion 1A and the third stirring member are opposed to each other and viewed in the developer transport direction by the third stirring member. Provided,
A developing device.
(Claim 2)
A developer carrier that carries and conveys a developer including toner and a carrier; and a side that is close to the developer carrier and adjacent to the longitudinal direction of the developer carrier, and the developer is disposed in a predetermined direction. A first agitating member that agitates while being conveyed, and a side far from the developer carrying member, adjacent to the longitudinal direction of the first agitating member, and the developer by the first agitating member A second stirring member that stirs the developer while transporting the developer in a direction opposite to the transport direction, and a housing that rotatably supports the developer carrier, the first stirring member, and the second stirring member. A developing device comprising a cover provided on an upper portion of the housing and configured to circulate and convey the developer by the first stirring member and the second stirring member;
A configuration in which the first stirring member and the second stirring member are extended to a side corresponding to the upstream side in the developer transport direction by the second stirring member and protrude from an end portion of the developer carrier. And
While configuring the second stirring member with a spiral rib,
The first stirring member is provided in the protruding region, has a helical rib and a plate-like rib provided in the rotation axis direction, and is lower than the second stirring member. 1 A of stirring parts which convey a developer in the same direction as the conveyance direction by the said 2nd stirring member with conveyance capability, and a spiral rib, and have the developer conveyance capability substantially the same as the said 2nd stirring member The second stirring member includes a stirring portion 1B that transports the developer in a direction opposite to the transport direction by the second stirring member, and further has a developer transport capability higher than that of the second stirring member. A third agitating member that conveys the developer in a direction opposite to the conveying direction by the above-described agitating portion 1A,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device.
(Claim 3)
A developer carrier that carries and conveys a developer including toner and a carrier; and a side that is close to the developer carrier and adjacent to the longitudinal direction of the developer carrier, and the developer is disposed in a predetermined direction. A first agitating member that agitates while being conveyed, and a side far from the developer carrying member, adjacent to the longitudinal direction of the first agitating member, and the developer by the first agitating member A second stirring member that stirs the developer while transporting the developer in a direction opposite to the transport direction, and a housing that rotatably supports the developer carrier, the first stirring member, and the second stirring member. A developing device comprising a cover provided on an upper portion of the housing and configured to circulate and convey the developer by the first stirring member and the second stirring member;
A configuration in which the first stirring member and the second stirring member are extended to a side corresponding to the downstream side in the developer transport direction by the first stirring member, and protrude from the end of the developer carrier. And
While configuring the second stirring member with a spiral rib,
The plurality of plate-like members provided in the first region and the plurality of plate-like members provided in the first direction and provided in the first direction, and provided in the second direction. A stirring portion 1A that has a lower plate-shaped member, has a lower developer conveying ability than the second agitating member, and conveys the developer in the same direction as the conveying direction by the second agitating member, and a spiral shape And a stirring portion 1B that transports developer in the direction opposite to the transport direction of the second stirring member, and has substantially the same developer transport capability as the second stirring member. ,
A third agitating member that has a higher developer conveying capability than the second agitating member and conveys the developer in a direction opposite to the conveying direction by the second agitating member is disposed opposite the agitating portion 1A. As well as
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device.
(Claim 4)
The peripheral surface of the developer carrying member and the first agitating member move in directions opposite to each other when viewed at their opposing proximity points. Development device. (Claim 5)
A rotatable developer supply / recovery member is provided between the developer carrier and the first agitating member, and the peripheral surfaces move in directions opposite to each other when viewed from the opposing proximity of both. The developing device according to claim 1.
(Claim 6)
When the volume average particle diameter of the toner is Dt [μm] and the volume average particle diameter of the carrier is Dc [μm],
Dt = 3-5
Dc = 5 · Dt ~ 10 · Dt
The developing device according to claim 1, wherein a developer including a toner and a carrier is used.
(Claim 7)
An image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image into a toner image.
While using the developing device of any one of Claims 1 thru | or 6 as said image development means,
The moving speed of the image carrier is V [mm / sec], the maximum adhesion amount per unit area of the toner image formed on the image carrier is M [mg / cm ² ], and the direction orthogonal to the moving direction of the image carrier The maximum width of the toner image is L [mm], the developer movement amount in the rotation axis direction of the developer carrier by the second stirring member is W [g / sec], and the rotation speed of the second stirring member is R [rpm]. When
W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus.
(Claim 8)
An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier A transfer unit that transfers the image to a transfer material or an intermediate transfer member; a cleaning unit that cleans the surface of the image carrier after the transfer; and a toner that is removed from the surface of the image carrier by cleaning is supplied to the developing unit. In an image forming apparatus having toner recycling means for recycling,
The developing device according to any one of claims 1 to 6 is used as the developing unit, and the position is on the cover of the developing device and between the stirring portion 1A and the third stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner.
(Claim 9)
9. The image forming apparatus according to claim 8, wherein the recycled toner supply port is located upstream of the toner supply port in the developer transport direction of the third stirring member.

  According to the developing device of the present invention, although the configuration is simple, in the transport process in the developer stirring unit, the toner in the developer is sufficiently mixed and stirred without decreasing the transport speed of the developer. Uniform dispersion can be achieved, and at the same time, a desired charge amount can be imparted to the toner, so that fog due to poor charging of the toner, occurrence of toner scattering, and the like can be suppressed as much as possible.

  Further, the first stirring member and the third stirring member can be rotated so that the respective peripheral surfaces move downward from above, and the toner can be replenished from above by facing between the opposing portions. By doing so, sinking of the replenishment toner into the developer and uniform dispersion can be accelerated, and good charge rising characteristics of the replenishment toner can be obtained.

  Further, since the axial length of the third stirring member may be shorter than the axial length of the first stirring member, for example, the developing device can be kept small for the effect to be achieved. In addition, since the container for storing the replenishing toner provided on the image forming apparatus main body side and the lower space where the toner recycling unit is installed can be used, the image forming apparatus does not need to be enlarged.

  Further, according to the image forming apparatus having the above-described configuration, the developing device as described above is provided, and the developer is sufficiently mixed and stirred by performing the developing process in a state satisfying specific operation conditions. The developer charged in a state in which the toner has a desired charge amount is supplied to the developer carrier at a uniform density in the rotation axis direction, and the latent image on the image carrier is developed with the developer. The

  Therefore, for example, when a developer in which a large amount of toner is consumed and replenished by continuous output of images with a high printing rate is used, or when the charging performance is inferior to that of unused toner, recycling is performed. Even when a developer containing toner is used, the desired charge amount can be imparted to the toner through efficient mixing and agitation, so that occurrence of toner scattering, fogging, image density unevenness, etc. can be suppressed as much as possible. A high-quality image can be stably produced.

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

  FIG. 1 is a schematic view showing a first embodiment of an image forming apparatus according to the present invention, FIG. 2 is a plan view showing the first embodiment of a developing apparatus according to the present invention, and FIG. AA sectional view in FIG. 2, FIG. 4 shows a BB sectional view in FIG.

  In the description, the developing device shown in FIGS. 2 to 4 will be described after the description of FIG. 1 showing the image forming apparatus composed of a digital color copying machine.

  The image forming apparatus according to the first embodiment has an automatic document feeder 1 at the top of the apparatus main body, and a belt for an image reading unit (image reading device) 2, an image forming unit 3, and a belt unit 4. Section, a sheet feeding section 5, a fixing device T, a reverse sheet discharge / refeed section 6, and an ADU 7 serving as a reverse conveying means.

  The automatic document feeder 1 is a device that feeds documents one by one, conveys them to an image reading position, and discharges the document after image reading to a predetermined location.

  The automatic document feeder 1 includes a document placing table 101 on which a document is placed, a document separating unit 103 for separating the placed document, a document transporting unit 105 for transporting the separated document, and discharging the transported document. A pair of rollers used to reverse the front and back surfaces of the original in the double-sided copy mode for reading the images on both sides of the original. The document reversing means 111 is provided.

  In view of the processing process, a plurality of documents (not shown) placed on the document placing table 101 are separated one by one by the document separating means 103, and the image reading position is passed through the document conveying section 105. It is conveyed toward.

  The document reading position is provided at a lower portion of the document conveying unit 105, where an image of the document is read through the slit 201 constituting the image reading device 2, and the read document is discharged from the document. The sheet is discharged onto the document discharge table 109 by the means 107.

  In the double-sided copy mode, the original document that has been read and transported on one side is conveyed by the document reversing means 111 in the direction indicated by the two-dot chain line arrow, and the original document is being bitten at the trailing edge in the direction of travel. The reverse rotation after the driving of the reversing unit 111 is stopped and the image is again guided to the image reading position via the document conveying unit 105, and then discharged onto the document discharge table 109 by the document discharge unit 107. Is done.

  The above process is repeated for the number of documents placed on the document placing table 101.

  The image reading device 2 includes a first mirror unit 205 and a first mirror 215 that are formed by integrating the slit 201, a lamp 213 for irradiating a document, and a first mirror 215 that reflects reflected light from the document. A second mirror unit 207 in which a second mirror 217 that reflects light and a third mirror 219 are integrated in a substantially V shape, and an image that forms an image of reflected light from the third mirror 219 on the image sensor. A lens 209 and a line-shaped image sensor (hereinafter referred to as a CCD) 211 that photoelectrically converts a light image formed by the imaging lens 209 to obtain image information are included.

  The image information is temporarily stored in a memory (not shown) after appropriate image processing.

  In a mode in which the document fed by the automatic document feeder 1 is read by the image reading device 2, the first mirror unit 205 and the second mirror unit 207 are fixed at positions as shown.

  The image signals for the respective colors read by the image reading device 2 are sequentially taken out from the memory and inputted as electric signals to the respective exposure optical systems which are electrostatic charge latent image forming means.

  The image forming unit 3 includes four image forming units (hereinafter referred to as image forming units) of yellow (Y), magenta (M), cyan (C), and black (BK) for forming a toner image corresponding to a color separation image. 30) is provided.

  Each of the image forming units 30 includes, for example, an image carrier (hereinafter referred to as a photosensitive drum) 310 in which a photosensitive layer made of a resin such as polycarbonate containing an organic photoconductor is provided on a drum-shaped metal substrate. Charger 320 of scorotron type, exposure optical system 330 as image writing means (synonymous with electrostatic charge latent image forming means), developing device 8 for developing electrostatic charge latent image, transfer means 340, photoconductor after transfer A cleaning device 350 including a blade (cleaning means) for cleaning the surface of the drum 310 is a main component.

  The developing device 8 incorporates a two-component developer containing a magnetic carrier (hereinafter simply referred to as carrier) and a non-magnetic toner (hereinafter simply referred to as toner), and is fixed in position and has a plurality of magnetic poles in the circumferential direction. And a developer carrying member (developing sleeve) having a rotatable and non-magnetic cylindrical shape incorporating a magnet in which the magnets are arranged.

  The exposure optical system 330 is an exposure unit composed of a laser optical system, and the transfer means 340 is opposed to a part of the peripheral surface of the photosensitive drum 310 via a rotating belt 401 described later. .

  Since the mechanical configuration of the four sets of image forming units described above is basically the same, reference numerals are assigned only to one set of units, and the others are omitted.

  Each of the image forming units 30 is provided with a flat surface (a stretched surface) A of a loop-shaped rotating belt (hereinafter referred to as an intermediate transfer belt) 401 that constitutes the belt unit 4 and is long in the belt installation portion. Are arranged in the order of yellow, magenta, cyan, and black from above.

  The intermediate transfer belt 401, support rollers 405, 406, 407, and a backup roller 410 that suspend the intermediate transfer belt so as to rotate are included in the belt unit 4, and the backup roller 410 includes the intermediate transfer belt. A secondary transfer unit is configured by a transfer roller 510 that is disposed so as to rotate while pressing the backup roller with 401 interposed therebetween.

  Image formation by the configuration of the image forming unit 30 and the belt unit 4 is performed as follows.

  As the image forming process starts, the surface of the photosensitive drum 310 that rotates counterclockwise is charged to a predetermined polarity by the charger 320.

  Next, the exposure optical system 330 performs exposure corresponding to the first color signal, that is, the yellow (Y) image signal, and a latent image corresponding to the (Y) image is formed on the photosensitive drum 310. Is done.

  The latent image is reversely developed by contact or non-contact development with a developer in the developing device 8 and converted into a toner image of (Y), and then transferred onto the intermediate transfer belt 401 by the action of the transfer unit 340.

  Image formation with other color signals, which is sequentially started after a predetermined time from the start of image formation with the first color signal, is performed in the same manner as described above, and each image of magenta (M), cyan (C), and black (BK). Each of the toner images is sequentially transferred so as to overlap with an image area where the toner image (Y) is formed, and a superimposed color toner image is formed on the intermediate transfer belt 401.

  On the other hand, the surface of the photosensitive drum 310 after completion of the transfer process is cleaned by the cleaning unit 350, and preparations for new image formation are made.

  Note that the start timing of each image forming process with respect to the photosensitive drum 310 or the intermediate transfer belt 401 is one side of the intermediate transfer belt 401, in the present embodiment, and the intermediate transfer belt 401. A registration sensor 413 provided in a section from a position where the transfer roller 510 is located to a position where the first set (yellow) image forming unit is provided is provided on the intermediate transfer belt 401. For example, time is measured starting from when a reference mark formed using paint is detected, and the (Y), (M), (C), and (BK) processes are sequentially started every predetermined time. It is configured.

  The detection signal from the registration sensor 413 is taken in, the time is monitored, and control related to individual processes is performed by a control unit (control means) S including a computer.

  Next, other configurations of the apparatus will be briefly described in connection with the process from when the color toner image formed on the intermediate transfer belt is transferred to the paper P and discharged to the outside of the apparatus.

  At an appropriate timing corresponding to the image formation on the intermediate transfer belt 401, the paper P is fed by the paper feed rollers 503 (513, 523) positioned in the feeding sections 501 (511, 521) of the paper feed section 5, It is conveyed toward the registration roller 551.

Thereafter, the sheet P is fed again so as to overlap with the color toner image area on the intermediate transfer belt 401 by resuming the rotation of the registration roller 551, and the backup roller 410 and the transfer roller in the secondary transfer unit. 510, the color toner image carried (formed) on the intermediate transfer belt 401 is transferred onto the sheet P while being pressed and nipped together with the intermediate transfer belt.
It is desirable that an appropriate transfer bias voltage is applied to the transfer roller 510 during transfer.

  The sheet P on which the toner image has been transferred is separated from the intermediate transfer belt 401 while being subjected to the action of a separation claw (not shown), and conveyed toward the fixing device T, for example.

  The fixing device T includes a fixing roller T1 having a built-in fixing heater and a pressure roller T2 that rotates while being pressed against the fixing roller. The color toner forming the image is heated and pressed by both rollers. It is melted and fixed on the paper P.

  The paper P after the fixing process by the fixing device T is completed is conveyed by a paper discharge roller 603 provided downstream thereof, and is discharged onto a paper discharge tray provided outside the apparatus main body.

  On the other hand, the surface of the intermediate transfer belt 401 after the completion of the secondary transfer is cleaned by a cleaning unit 415 including a blade, and preparations for carrying a new toner image are made.

  Note that the toner in the developer is consumed by the development process. This is because a toner concentration detection sensor is provided at an appropriate place in the developing device 8 and the toner in the developing device is based on information from the sensor. Can be provided by known techniques.

  In the figure, the solid line position of the path switching member 601 is a position held when the upper and lower surfaces of the paper P are reversed and discharged after the fixing process, and the broken line position is sent out from the fixing device as described above. This position is held when the sheet is discharged as it is.

  For example, in the reverse discharge of the paper P, the paper P sent out from the fixing device T is guided downward along the right side of the path switching member 601, and the rear end in the advancing direction is held by the roller pair 602. It is lifted by the reverse rotation of the roller pair 602 after being set in the closed state, passes through the left side of the switching member 601, reaches the paper discharge roller 603, and is discharged so as to be discharged by the paper discharge roller. Is done.

  Further, the behavior of the paper P in the double-sided copy mode using the ADU 7 is similar to that in the case of the reverse discharge. The paper P after the fixing process with the image formed on one side is moved along the right side of the switching member 601. Then, after stopping the conveyance with the rear end of the paper P in the traveling direction being sandwiched by the roller pair 605, the roller pair 605 is rotated in the reverse direction and is raised along the guide plate G, and a plurality of roller pairs The reversal of the paper P is achieved by leading to the ADU 7 having 701, 703, and 705.

  The image forming process for the second surface of the paper P is the same as described above, and any one of the above-mentioned is selected for the discharge after being sent out from the fixing device T.

  Next, the configuration of the developing device which is a toner image forming unit (developing unit) will be described in detail with reference to FIGS.

  In the present specification, the left-right direction in FIG. 2 is referred to as “front-rear direction” with reference to the developer carrier, and the up-down direction in FIG. It is called “rotational axis direction” or “longitudinal direction”, and the vertical direction in FIGS. 3 and 4 is expressed as “vertical direction”.

  The developing device 8 includes a developer carrier (developing sleeve) 800 that carries and conveys the developer, and a position closer to the developer carrier, adjacent to the longitudinal direction of the developer carrier. A first agitating member 803 that is provided (or parallel to the longitudinal direction) and agitates while conveying the developer in a predetermined direction as a whole, and a position far from the developer carrier, A second agitating member 805 provided adjacent to (in parallel with) the longitudinal direction of the first agitating member and agitating while conveying the developer in a direction opposite to the developer conveying direction by the first agitating member 803; Provided between the developer carrying member 800 and the first stirring member 803, the developer is supplied to the developer carrying member, and the developer removed from the developer carrying member is supplied from the supply / recovery unit 815 to the storage stirring unit. Supply developer to 816 A collecting member 809, a housing 810 for rotatably supporting a rotating member such as the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member; And a cover 812 provided on the upper portion of the housing.

  In addition, the developer carrier 800 and the developer supply / recovery member 809 have substantially the same length and are configured so that both end portions have substantially the same position. The member 803 and the second stirring member 805 are configured to be longer than the length of the developer carrier 800 and the like.

  And one end position of both agitating members (the downstream end when viewed in the developer conveying direction by the second agitating member, the upstream end when viewed in the overall conveying direction of the developer by the first agitating member) ) Is positioned substantially in the same plane as the end portion position of the developer carrier 800, so that the other end portion projects together with the housing 810 from the end portion of the developer carrier 800.

  In other words, the second stirring member 805 extends and protrudes upstream in the developer transport direction. Reference numeral 802 indicates a protruding region.

  In addition, the developing device 8 is in a housing corresponding to the protruding region 802 and is substantially on an extension line to which the developer supply / recovery member 809 is attached (the first stirring member 803 is sandwiched between The second stirring member 805 is provided at a position opposite to the second stirring member 805 to be opposed to a partial region of the first stirring member 803 and provided with a rotatable third stirring member 807.

  The developer carrier 800 is a cylindrical member made of a non-magnetic metal material such as aluminum or stainless steel, and a magnet (not shown) is housed in a fixed position therein.

  As is well known, the magnet can automatically attract and hold the developer on the developer carrier and remove the developer from the developer carrier 800 using a repulsive magnetic field. It is configured to be able to.

  As described above and as shown in FIG. 3, the developer carrier 800, the developer supply / recovery member 809, and the first stirring member 803 are supplied with the developer formed in the housing 810 by the partition wall 808. The second agitation member 805 is accommodated in the developer agitation unit 816.

  The partition wall 808 provided between the first stirring member 803 and the second stirring member 805 is shorter than the first and second stirring members in a state in which both end portions in the longitudinal direction are notched. The outer regions of the end portions are passages for developer circulation (sometimes referred to as circulation passages) 820 and 821.

  The supply / recovery unit 815 and the storage agitation unit 816 store an appropriate amount of two-component developer including carrier and toner.

  Since the partition wall 808 can prevent the developer in the supply / recovery unit from being mixed with the developer in the storage and agitation unit, the developer having a predetermined charge amount is sequentially supplied to the developer carrier. It can be done, but it can be eliminated.

  The rotating member such as the stirring member is configured to receive power from a drive system provided on the image forming apparatus main body side and rotate in the direction of the arrow through a gear or the like. Can be used.

  In the present embodiment, the developer carrying member 800 arranged to face the already-exposed photoconductive drum 310 is counterclockwise (the photoconductive drum is opposite to the photoconductive drum in the opposite direction), and developer supply / recovery is performed. The member 809 rotates counterclockwise, the first stirring member 803 rotates counterclockwise, the second stirring member 805 rotates clockwise, and the third stirring member 807 rotates clockwise.

  These agitating members are formed on the outer peripheral surface of the shaft (rotating shaft) J as shown in FIG. 5, for example, on the outer peripheral surface of the shaft and with a predetermined direction in the axial direction and a predetermined pitch p. It can be configured by providing a spiral rib (screw) 850.

  Further, as the developer supply / recovery member 809, for example, a rotary member configured in a paddle shape by providing a plate-like blade member projecting radially outward from the circumferential surface of the rotary shaft can be suitably used.

  By defining the rotation direction of the developer carrier 800 and the developer supply / recovery member 809 as described above, the developer supplied from the developer supply / recovery member 809 to the developer carrier 800, and the developer Since the developer removed from the carrier 800 and the developer recovered by the developer supply / recovery member 809 can be reliably replaced, the toner density of the developer on the developer carrier 800 can be kept uniform. As a result, the occurrence of uneven image density can be easily suppressed.

  In the drawing, Z indicates a layer thickness regulating blade for regulating the thickness of the developer layer that is magnetically attracted and carried on the developer carrying member 800.

  Returning to FIG. 2, the thick arrows indicate the developer transport direction when the first stirring member 803, the second stirring member 805, and the third stirring member 807 rotate in the above directions, and the length of the arrows is , Developer transport capability (developer transport speed, developer transport amount, etc.).

  The first agitating member 803 has substantially the same conveying ability as a second agitating member 805 described later, and agitates for conveying the developer in a first direction (in the drawing, the rotation axis direction from the upper side to the lower side). The part 1B and the end part integral with the stirring part 1B (refers to a part corresponding to the projecting region. Since the entire developer is transported from the upper side to the lower side in the figure, the first It can be said that the agitating member is at a downstream position in the developer conveying direction.), And has a conveying ability lower than the conveying ability of the second agitating member, and the developer is conveyed in the same conveying direction as the second agitating member 805. 1A of stirring parts conveyed in a direction.

  The second agitating member 805 has a predetermined conveying capacity, and conveys the developer in a direction opposite to the overall (overall) conveying direction of the first agitating member 803, thereby enabling the developer to be circulated and conveyed. And

  The third agitating member 807 has a larger developer conveying capability than the second agitating member 805, and conveys the developer in the direction opposite to the conveying direction of the second agitating member.

  The conveying ability of each stirring member is determined by the amount of developer to be supplied to the developer carrier 800 (including the developer conveying speed in the axial direction), the smooth flow of the developer in the circulation conveying path, or The desired charge amount to be applied to the toner can be determined as appropriate according to the required conditions.

  The portion of the stirring member corresponding to the downstream side in the developer transport direction by the first and second stirring members 803 and 805 corresponding to the circulation passages 820 and 821 described above can be easily transferred. For example, a plate-like blade member that protrudes radially outward from the peripheral surface of the rotating shaft is provided in an appropriate range to have a paddle shape.

  According to the developing device having the above-described configuration, the developer in the storage stirring unit 816 is conveyed in the axial direction indicated by the arrow while being stirred in the circumferential direction by the rotation of the second stirring member 805, and is passed through the passage 820. Thus, the first stirring member 803 is affected.

  The developer conveyed in the direction opposite to the conveying direction by the second agitating member 803 while being agitated in the circumferential direction with the rotation of the first agitating member 803 is sequentially supplied via the developer supply / recovery member 809. It is supplied to the carrier 800.

  On the other hand, the developer that has been removed from the developer carrying member 800 and has been subjected to the action of the developer supply / recovery member 809 is mixed with the other developer conveyed by the first stirring member 803 to the stirring portion 1A. To reach.

  Some of the developer in the region of the stirring portion 1A is transported in the same direction as the transport direction by the second stirring member, but is pushed by the subsequent developer and moves downward in the figure while being stirred. When the action of the third agitating member 807 is received, it is rapidly conveyed downward, and again receives the action of the second agitating member 805 via the passage 821, and the above-described movement is repeated for a necessary time.

  Note that the developer containing the toner to which the desired charge amount is given by the mixing / stirring action during the circulation and conveyance is subjected to development processing, and the toner is consumed for visualization.

  The developer after the development processing is detected by the toner concentration detection sensor, and based on the detected value, unused toner (hereinafter referred to as new toner) passes through the toner supply port 813 from a toner supply mechanism (not shown). Supplied through.

  The toner supply port 813 has a substantially intermediate position where the stirring portion 1A of the first stirring member 803 and the third stirring member 807 face each other (as shown in the sectional view of FIG. 1A) and the third agitating member 807 are located on the cover 812 corresponding to an appropriate upstream position in the developer conveying direction by the third agitating member. It is.

  The toner replenishing mechanism is provided, for example, on the apparatus main body side and above the toner supply port 813.

  The position of the toner supply port 813 is the upstream position as described above, which is intended to achieve effective mixing and stirring even when the axial length of the stirring portion 1A and the third stirring member 807 is short. It is.

  Therefore, when the stirring portion 1A has a sufficient length, it is not necessary to be so upstream, but even in that case, the new toner is uniformly dispersed in the developer, and the charge amount is given by the developer friction. In consideration of the above, it is preferable to be on the upstream side.

  The supplied toner is efficiently stirred with the developer by the rotation of the stirring portion 1A and the third stirring member 807.

  In other words, the stirring portion 1A of the first stirring member 803 and the third stirring member 807 are rotated such that the peripheral surfaces move in the forward direction from the upper side to the lower side when viewed from the opposing proximity point of both ( For example, when paying attention to one point on the peripheral surface of the stirring member made of a screw, the one point reaches the proximity point from above with respect to the proximity point and rotates about the axis so as to come out downward) As a result, the supplied toner can be quickly submerged in the developer.

  As described above, the mixing stirring time can be increased by the stirring portion 1A of the first stirring member 803, and new toner is replenished depending on the rotation direction of the third stirring member and the first stirring member. However, the toner can be favorably dispersed and charged, and the developer stirrability of the third stirring member 807 can suppress the occurrence of developer stagnation in the vicinity of the communicating portion.

  Further, since sufficient agitation can be performed in the circumferential direction of the agitating member without reducing the developer conveyance speed, for example, a developer having a uniform toner concentration in the axial direction of the second agitating member can be obtained in a short time. And it becomes possible to obtain easily.

  The toner used in the developing device preferably has a volume average particle size of 3 to 5 μm. Such a small particle size toner is a toner image having high resolution and excellent fine line reproducibility. In addition, it is possible to form a toner image having a stable image density in the solid portion (solid image portion).

  The toner having a small particle diameter can be produced by, for example, a polymerization method.

  The carrier is preferably 5 × Dt to 10 × Dt [μm] when the volume average particle diameter of the toner is Dt [μm].

  By using a carrier having a volume average particle size of 5 to 10 times the volume average particle size of the toner, the charge imparting performance of the carrier surface can be improved even when a small particle size toner is used, As a result, the occurrence of fogging and toner scattering can be suppressed, and a uniform image density and a fine high-quality image can be obtained.

  Further, in the image forming apparatus described above, the developing process by the developing device 8 is performed in a state adjusted to the operation setting conditions satisfying the following conditions (A) and (B).

Condition (A); W ≧ M × V × L / 1000
Condition (b); R ≦ 600
In the above conditions (a) and (b), V is the peripheral speed [mm / sec] of the image carrier, and M is the maximum amount of adhesion per unit area of the toner image formed on the image carrier [mg / cm ^2]. ], L is the maximum width [mm] of the toner image in the direction (axial direction) orthogonal to the moving direction of the image carrier, W is the developer movement amount [g / sec] in the rotation axis direction of the second stirring member, and R Indicates the rotation speed [rpm] of the second stirring member.

  It can be said that W is a developer movement amount of the first stirring member portion 1B capable of transporting the same amount of developer as the second stirring member. Therefore, the W and R depend on the stirring portion 1B of the first stirring member. The amount of movement of the developer can be replaced with the number of rotations of the first stirring member.

  When the developer movement amount (developer conveyance amount) W in the rotation axis direction by the second agitating member 805 is excessively small, as a result, in the developer supply region downstream of the developer supply and recovery member in the developer conveyance direction. The toner concentration in the developer is lowered, it becomes difficult to supply a sufficient amount of toner to the development area, and uneven image density is likely to occur.

  In addition, when the number of rotations of the second stirring member 805 is excessive, the developer is likely to be deteriorated by heat generated at the shaft portion of the second stirring member 805, and a high-quality image can be formed. It becomes difficult.

  In other words, the developer in a state where there is no toner density unevenness in the axial direction of the developer carrying member by performing the development process in a state satisfying the specific conditions (a) and (b) of the image forming apparatus. Since the developer can be supplied to the development area through the rotation of the developer carrying member, an image having a uniform image density without image density unevenness can be formed.

  Further, by setting the rotation speed of the second stirring member (the same applies to the first stirring member) to 600 rpm or less, the developer is prevented from being deteriorated by heat generated when the second stirring member is rotated at a high speed. be able to.

  As described above, according to the image forming apparatus having the above-described configuration, the toner and the carrier are sufficiently mixed and agitated to obtain sufficient charge rising characteristics of the toner, and the developer is uniform in the axial direction. The toner is supplied to the development area with a high toner density.

  Therefore, for example, when a developer in which a large amount of toner is consumed and replenished by continuously outputting images with a high printing rate is used, or the number of images formed per minute (number of printed sheets) is 50 sheets. Even when image formation is performed at such a high process speed, fog or toner scattering does not occur, and a high-quality image without image density unevenness can be formed.

  Although the developer supply / recovery member is provided in the above-described embodiment, the developer supply / recovery member can be eliminated, and the first stirring member can be used as the developer supply / recovery member.

  Next, a specific configuration example of a rotating member that can be used as a stirring member will be described with reference to FIGS.

  In the figure, the same reference numerals are assigned to the same members as those already described. In addition, the rotating member refers to a single member before being incorporated into the developing device, which has a configuration that can be used as a stirring member or a developer supply member. Although referred to as a stirring member or the like, it is not distinguished here for convenience.

  FIG. 5 is a schematic diagram showing a first example of the agitating member. As described above, a predetermined pitch (screw pitch) is provided in the axial direction over the entire circumference of the outer peripheral surface of the shaft (hereinafter also referred to as a rotating shaft) J. p, a rotating member composed of a spiral rib (screw) 850 formed with a predetermined direction (shown in one direction in the figure).

  The stirring member having the above configuration can be basically used for any of the first to third stirring members.

  For example, when the developer transport capability of the spiral rib having the pitch p is used as a reference, if the developer transport capability is desired to be lower than that, the pitch p1 is set to be smaller than the pitch p. The developer conveying ability in the direction of the rotation axis can be lowered. Conversely, if the pitch p2 is larger than the pitch p, the developer conveying ability in the direction of the rotation axis can be increased.

  For example, when an attempt is made to configure the stirring member in the developing device shown in FIGS. 2 to 4 by such a spiral rib, the following may be performed.

  That is, the second stirring member 805 is configured by a spiral rib in one direction having a reference pitch p, and the stirring portion 1A of the first stirring member 803 has a pitch p1 smaller than the pitch p, and The direction of the spiral is determined so that the developer can be conveyed in the same direction as the conveyance direction by the second agitating member 805, and the agitating portion 1B is formed by a helical rib having a pitch p, and by the second agitating member 805 The direction of the spiral is determined so that the developer can be conveyed in the direction opposite to the conveying direction, and the third agitating member 807 has a pitch p2 larger than the pitch p, and the second agitating member 805 This can be achieved by determining the direction of the spiral so that the developer can be transported in the direction opposite to the transport direction.

  In the first example and other examples described below, for example, the configuration of the downstream end portion in the developer transport direction of each stirring member (in the stirring portion 1A in the first stirring member in FIG. Although it can be said that it is not an upstream end portion, since the developer transport direction by the first stirring member is substantially from the upper side to the lower side in the drawing, such an end portion is the downstream end portion of the first stirring member. ) Preferably has a paddle shape as described above.

  The stirring member of the second example shown in FIG. 6 includes a plurality of plate-like members provided on the rotation axis J and inclined in the first direction, and a plurality of plate-like members provided inclined in the second direction. It has a member.

  More specifically, for example, the plate-like members 851 and 852 made of semi-elliptical plates are inclined in different directions at the axial center with respect to the same plane perpendicular to the rotational axis J on the outer peripheral surface of the rotational axis J. And a plurality of such sets are arranged in the axial direction at a predetermined pitch p.

  The attachment angles α1 and α2 of each plate-like member with respect to the rotation axis J may be the same size or different, and can be appropriately determined according to the purpose.

  The stirring members of the third to fifth examples shown in FIGS. 7 to 9 have the basic structure of the stirring member shown in FIG. 5, but further increase the developer stirring ability.

  The stirring member shown in FIG. 7 is on the outer periphery of the rotating shaft J, on the outer periphery of the rotating shaft J, and on the outer periphery of the rotating shaft J and the spiral rib 850 formed at a pitch p having a predetermined size in the axial direction. A plate-like rib (vertical blade) 855 including a rod-like shape is provided so as to extend outward in the radial direction.

  The ribs 855 are provided one for each pitch p of the spiral ribs 850, and are provided in a line (linearly) in the direction of the rotation axis.

  However, the rib 855 can be provided in the axial direction with the phase shifted on the rotation axis J when the drawing is viewed from the side.

  The stirring member shown in FIG. 8 is on the outer periphery of the rotating shaft J and on the outer periphery of the rotating shaft J, and the spiral rib 850 formed at a pitch p having a predetermined size in the axial direction. Rod-like or plate-like ribs (vertical blades) 856 provided in a row in the direction of the rotation axis, and the ribs 856 are configured in a plurality of rows.

  For example, when the figure is viewed from the side, the ribs 856 have a four-row arrangement in which the phase is shifted by 90 degrees in the circumferential direction of the rotation axis J.

  The length (meaning width) W of the plate-like rib 856 in the rotation axis direction is configured to be larger than the width W of the plate-like rib 855 shown in FIG. Etc. are only required to achieve the intended purpose, and the degree of freedom in design is wide.

  The stirring member shown in FIG. 9 includes a spiral rib 850 that is formed on the entire outer peripheral surface of the rotating shaft J and has a pitch p of a predetermined size in the axial direction, and is provided at the outer peripheral edge of the spiral rib. Is formed with a notch 857 penetrating in the axial direction.

  For example, when the figure is viewed from the side, the notches 857 have a two-row arrangement in which the phases are shifted by 180 degrees in the circumferential direction of the rotation axis J. In the drawing, U indicates the length (meaning width) of the notch in the circumferential direction, and t indicates the length of the notch in the radial direction.

  Next, a sixth example and a seventh example of a stirring member having a developer stirring ability higher than that of the stirring member described so far will be described with reference to FIGS.

  The stirring member shown in FIG. 10 includes a helical rib 850 formed over the entire outer peripheral surface of the rotating shaft J and at a predetermined pitch p in the axial direction of the rotating shaft J, and an outer peripheral edge portion of the helical rib. And a plate-like rib 858 extending linearly in the direction of the rotation axis J.

  In this example, plate-like ribs are provided at two locations (upper edge and lower edge in the drawing) that are axial objects.

  The agitating member shown in FIG. 11 has the same basic configuration as that of FIG. 6 and is semi-elliptical on the outer peripheral surface of the rotation axis J and in different directions at the axis center with respect to the same plane perpendicular to the rotation axis. The plate-like members 851 and 852 made of plates are provided to be inclined, and a plurality of such sets are arranged in the axial direction at a predetermined pitch p, and the outer peripheral edges of the plate-like members 851 and 852 A plate-like rib 858 extending linearly in the direction of the rotation axis J is provided.

  In this example, four plate-like ribs 858 are provided at equal intervals in the circumferential direction.

  These agitating members rotate around the rotation axis J to agitate the developer in the circumferential direction in the process of transporting the developer in the axial direction, and plate-like ribs as auxiliary agitating members Even at 858, stirring is performed in the circumferential direction.

  5 to 11 are embodiments that can be used as the first stirring member to the third stirring member or the developer supply / recovery member, and any combination can be used as long as the intended purpose can be achieved. Needless to say, it can be used.

  As described above, according to the developing device provided with the stirring member provided with the plate-like rib serving as an auxiliary member for stirring, the above-described operation and effect can be obtained more reliably, and due to poor charging of the toner. Occurrence of fogging and toner scattering can be further suppressed.

  In addition, it is possible to more reliably suppress the occurrence of image density unevenness due to the non-uniformity of the toner density in the axial direction of the developer supplied to the developing carrier.

  Therefore, according to the image forming apparatus provided with such a developing device, the developer containing the toner having the desired charge amount and having a uniform toner density is sufficiently agitated with sufficient agitation. Since the latent image on the photosensitive drum is developed by the developer in the direction, problems such as toner scattering, fogging, and image density unevenness can be suppressed, and a higher quality image can be produced.

  In the above, the embodiment of the image forming apparatus according to the present invention has been described as an image forming apparatus capable of producing a color image having a plurality of developing devices. It can also be enjoyed when applied to a conventional image forming apparatus.

  Next, an image forming apparatus according to the second embodiment will be described.

  The image forming apparatus shown in FIG. 12 has toner recycling means (toner recycling apparatus) that collects toner removed from the photosensitive drum after transfer, and finally returns the toner to the developing apparatus for reuse.

  The image forming apparatus shown in FIG. 12 is composed of a monochrome digital copying machine, and includes a basic configuration as a copying machine, such as an automatic document feeder, an image reading unit, an image forming unit, a paper feeding unit, a fixing device, and the like. However, these can be understood from the drawings and explanations relating to the first embodiment, and the developing device 8 has basically the same configuration as that of the first embodiment. The main parts are only shown schematically.

  Further, in the figure, the same reference numerals are assigned to the same members (means) as those already described.

  In the figure, 310 is a photosensitive drum as an image carrier, 320 is a charger, 330 is an exposure optical system (writing means) including a laser light source, 8 is a developing device, 350 is a cleaning device, and P is paper.

  A transfer electrode and a separation electrode are provided between the developing device 8 and the cleaning device 350 in the rotational direction of the photosensitive drum.

  The cleaning device 350 has cleaning means including a blade 352 that contacts the surface of the photoconductive drum 310 in a counter direction at an upper position in the container 351 and toner removed by the blade 352 (hereinafter referred to as recycling). A rotatable collection member 353 made of a screw that conveys toner (also referred to as toner) in a predetermined direction (front side in the drawing) in the axial direction of the photosensitive drum is provided at a lower position in the container 351.

  Reference numeral 9 denotes a toner recycling means, which receives the recycled toner transported and collected by the collecting member 353 and transports it toward the developing device 8, and is a rotatable transporting means 901 made of a screw (for convenience, two points) (Shown with a chain line).

  The basic shapes of the recovery member 353 and the conveying means 901 are the same as those shown in FIG.

  The conveying means 901 is built in a cylindrical outer frame 903 (shown by a two-dot chain line for the sake of convenience), and the recycled toner is supplied to the developing device 8 at the tip of the outer frame 903. The opening 905 is aligned with the recycled toner supply port 825 provided on the cover 812 of the developing device 8 so that there is no toner leakage.

  The recycled toner supply port 825 is within a range where the stirring portion 1A of the first stirring member 803 and the third stirring member 807 face each other, and when viewed from the side, is at an approximately intermediate position between the two stirring members. Thus, it is provided on the cover 812 corresponding to an appropriate position on the upstream side of the toner supply port 813 as viewed in the developer conveying direction by the third stirring member.

  The positional relationship between the toner supply port 813 and the recycled toner supply port 825 in the longitudinal direction of the developing device 8 is shown in FIG. 13 which is a schematic diagram of the developing device.

  On the other hand, the distance between the two is not particularly limited, but it is practically preferable to provide the recycled toner supply port 825 at an upstream position of about 5 to 30 mm from the toner supply port.

  The recycled toner is supplied with its supply amount adjusted so that the ratio of recycled toner to new toner in the developer (recycled toner ratio) is maintained at 50% by mass or less.

  With the developing device having such a configuration, the mixing and stirring time of the recycled toner, which is poor in fluidity and lower in chargeability than the new toner, can be increased. And the occurrence of fogging and toner scattering due to poor charging of the toner can be suppressed, and the occurrence of uneven image density in image formation can be suppressed.

  Further, in the image forming apparatus including the developing device having the above-described configuration, a developer in which a large amount of toner consumption and replenishment of toner including recycled toner are repeatedly performed by continuously outputting an image with a high printing rate is used. Even when image formation is performed at a high process speed such that the number of image formations per minute is 50 or more, occurrence of fogging and toner scattering can be suppressed, and uneven image density can be achieved. Therefore, a high-quality image having a uniform density can be formed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said aspect, A various change can be added.

  For example, the configuration of the pitch of the spiral ribs, the shape and size of the plate-like ribs, the number of rotations of the stirring member, and the like can be appropriately determined depending on the purpose.

Next, experimental examples conducted for confirming the effects of the present invention will be described.
[Production of rotating member]
A rotating member used as a first stirring member, a second stirring member, a third stirring member, or a developer supply / recovery member was produced as described below.
(Rotating member AA)
As shown in FIG. 5, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, and the outer peripheral surface of the shaft member spans a length of 30 mm on the downstream side in the developer conveyance direction by the spiral rib. On the top, four flat blade members are provided so as to extend radially outward to form a paddle shape, and further, a disk-shaped flange member having an outer dimension of 24 mm is provided at both ends of the rotating member. Rotating member.

  The specifications of the rotating member AA are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm
(Rotating member EE)
As shown in FIG. 9, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, a notch is provided on the outer peripheral edge of the spiral rib, and the spiral rib is Four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the transport direction of the developer so as to extend outward in the radial direction to form a paddle shape, and external shapes are provided at both ends of the rotating member. A rotating member having a configuration in which a disk-shaped flange member having a dimension of 24 mm is provided.

  The specifications of the rotating member EE are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm, Radial length of notch (t): 5 mm, circumferential length of notch (U): 2 mm, notch: 4 locations per pitch (equally spaced)
(Rotating member GG)
As shown in FIG. 7, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, and a plurality of plate-like ribs (vertical blades) extending radially outward are provided in the longitudinal direction of the shaft. And four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the developer conveyance direction by the spiral ribs so as to extend radially outward to form a paddle shape. In addition, a rotating member having a configuration in which disk-shaped flange members having an outer dimension of 24 mm are provided at both ends of the rotating member.

  The specifications of the rotating member GG are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm, Arrangement of plate-like ribs: one per pitch (center position between screw pitches), length of plate-like ribs in the axial direction (W): 3 mm, length of plate-like ribs in radial direction (h ): 8 mm, plate-like rib thickness: 1 mm
(Rotating member II)
As shown in FIG. 8, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, and a plurality of plate-like ribs (vertical blades) extending radially outward are provided in the longitudinal direction of the shaft. And four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the developer conveyance direction by the spiral ribs so as to extend radially outward to form a paddle shape. In addition, a rotating member having a configuration in which disk-shaped flange members having an outer dimension of 24 mm are provided at both ends of the rotating member.

  The specifications of the rotating member II are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm, Arrangement of plate-like ribs: four at regular intervals per pitch, length (W) in the axial direction of plate-like ribs: 12 mm, length in radial direction of plate-like ribs (h): 8 mm, plate Rib thickness: 1mm
(Rotating member JJ)
The rotating member II has the same configuration as the rotating member II except that the length of the plate-like rib in the axial direction is 20 mm.
(Rotating member KK)
As shown in FIG. 10, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, and a plate-like rib extending in the axial direction without a break on the outer peripheral edge of the spiral rib. And four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the developer conveyance direction by the spiral ribs so as to extend radially outward to form a paddle shape. In addition, a rotating member having a configuration in which disk-shaped flange members having an outer dimension of 24 mm are provided at both ends of the rotating member.

  The specifications of the rotating member KK are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm, Radial length of plate-like rib (t): 3 mm, plate-like rib thickness: 1 mm, plate-like rib mounting location: two axially symmetric locations (rotating member LL)
The rotating member KK has the same configuration as the rotating member KK except that the radial length (t) of the plate-like rib is 5 mm.
(Rotating member MM) A rotating member having the same configuration as the rotating member KK except that four plate-like ribs are provided at equal intervals on the outer peripheral edge of the spiral rib in the rotating member KK.
(Rotating member WW)
As shown in FIG. 6, a first stirring unit and a second stirring unit configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member. And a rotating member having a disk-like flange member having an outer dimension of 24 mm at both ends of the rotating member.

  The specifications of the rotating member WW are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, thickness of plate member: 1 mm, shaft of plate member constituting first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring section: −45 °, plate-like member arrangement pitch: 25 mm
(Rotating member XX)
As shown in FIG. 11, a first stirring unit and a second stirring unit configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member. And on the outer peripheral edge of the plate-like member constituting the first stirring unit and the second stirring unit and extending in the axial direction at four positions that are equally spaced in the circumferential direction. A rotary member having a configuration in which plate-like ribs are provided and disk-like flange members having an outer dimension of 24 mm are provided at both ends of the rotary member.

  The specifications of the rotating member XX are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, thickness of plate member: 1 mm, shaft of plate member constituting first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring section: −45 °, pitch of plate-like member (p): 25 mm, plate-like rib Radial length (t): 3 mm, plate-like rib thickness: 1 mm
(Rotating member QQ)
As shown in FIG. 14, plate-like ribs (flat blade members) 859 extending in the radially outward direction and in the longitudinal direction of the shaft are provided from four equally divided portions in the circumferential direction of the shaft to form a cross paddle Rotating member consisting of

  The specifications of the rotating member QQ are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft part: 360 mm, outer diameter of the shaft member: 6 mm, thickness of the plate-like rib: 1 mm, radial length of the plate-like rib (h) : 9mm
(Rotating member D)
The rotating member AA has the same configuration as the rotating member AA except that the spiral rib is formed in a right-handed manner, the screw pitch of the spiral rib is 40 mm, and the axial length is 110 mm. A rotating member having.
(Rotating member NA)
As the stirring portion 1A, a spiral rib (right-handed) including a plate-like rib extending in the axial direction shown in FIG. 10 as the stirring portion 1A, and a spiral rib (left-handed) shown in FIG. 5 as the stirring portion 1B. And four flat blade members are provided to extend radially outward on the outer peripheral surface of the shaft member having a length of 30 mm on the downstream side as viewed in the overall developer conveyance direction. The rotating member is configured to have a paddle shape and a disc-shaped flange member having an outer dimension of 24 mm at both ends of the rotating member.

  The specifications of the rotating member NA are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion 1A is 110 mm, stirring portion 1B is 330 mm), shaft member outer diameter: 6 mm, pitch of spiral rib (P): 20 mm for the stirring portion 1A, 30 mm for the stirring portion 1B, thickness of the spiral rib: 1 mm, radial length of the plate-like rib (t): 3 mm, axial length of the plate-like rib: 110 mm, arrangement of plate-like ribs: 2 positions of axial object, thickness of plate-like ribs: 1 mm
(Rotating member WA)
As the stirring portion 1A, a first stirring portion configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member shown in FIG. 5 as a stirring portion 1B, and integrally with the spiral rib (left-handed) shown in FIG. 5, and the length on the downstream side in the overall developer transport direction. On the outer peripheral surface of the shaft member extending over 30 mm, four flat blade members are provided so as to extend radially outward to form a paddle shape, and disk-shaped flanges having an outer dimension of 24 mm at both ends of the rotating member A rotating member having a structure provided with a member.

  The specifications of the rotating member WA are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft part: 440 mm (however, the stirring part 1A is 110 mm, the stirring part 1B is 330 mm), and the plate member constituting the first stirring part is attached to the shaft Angle (α1): + 45 °, Mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring unit: -45 °, plate-like member thickness: 1 mm, plate-like member arrangement pitch: 25 mm, spiral Rib pitch: 30 mm, spiral rib thickness: 1 mm
(Rotating member XA)
As shown in FIG. 11, as the stirring portion 1 </ b> A, a first stirring portion configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member And the second stirrer, and on the outer peripheral edges of the plate-like members constituting the first stirrer and the second stirrer, at four positions equidistant in the circumferential direction. 5 has a configuration in which plate-like ribs extending in the direction are provided, and integrally has a helical rib (left-handed) shown in FIG. 5 as the stirring portion 1B, and the developer is transported as a whole. Four flat blade members are provided on the outer circumferential surface of the shaft member extending 30 mm downstream in the direction so as to extend outward in the radial direction to form a paddle shape, and external dimensions are provided at both ends of the rotating member. It was set as the structure which provided the disk-shaped flange member of 24 mm. The rolling member.

  The specifications of this rotating member are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis excluding shaft portion: 440 mm (however, stirring portion 1A is 110 mm, stirring portion 1B is 330 mm), relative to the axis of the plate-like member constituting the first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate member constituting the second stirring section: −45 °, plate member thickness: 1 mm, plate member arrangement pitch: 25 mm, The radial length (t) of the plate-like rib: 3 mm, the axial length of the plate-like rib: 110 mm, the thickness of the plate-like rib: 1 mm, the pitch of the helical rib: 30 mm, the length of the helical rib Thickness: 1mm
(Rotating member OE)
As the stirring portion 1A, a spiral rib (right-handed) including a plate-like rib extending in the axial direction shown in FIG. 10 as a stirring portion, and as a stirring portion 1B, a spiral shape with a notch portion shown in FIG. Four flat blade members are extended radially outwardly on the outer peripheral surface of the shaft member that has a rib (left-handed) and has a downstream length of 30 mm as viewed in the overall developer conveyance direction. A rotating member provided with a paddle shape and a disc-shaped flange member having an outer dimension of 24 mm provided at both ends of the rotating member.

  The specifications of the rotating member OE are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 440 mm (however, the stirring portion 1A is 110 mm, the stirring portion 1B is 330 mm), the pitch of the spiral ribs (p): 30 mm, spiral Rib thickness: 1 mm, radial length of plate-like rib (t): 5 mm, axial length of plate-like rib: 110 mm, arrangement of plate-like ribs: two axially symmetrical, plate-like ribs Rib thickness: 1 mm, radial length (t) of cutout portion: 5 mm, circumferential length of cutout portion (U): 2 mm, cutout portion: 4 locations per pitch (equally spaced)
(Rotating member PE)
As the stirring portion 1A, a spiral rib (right-handed) including a plate-like rib extending in the axial direction shown in FIG. 10 as a stirring portion, and as a stirring portion 1B, a spiral shape with a notch portion shown in FIG. Four flat blade members are extended radially outwardly on the outer peripheral surface of the shaft member that has a rib (left-handed) and has a downstream length of 30 mm as viewed in the overall developer conveyance direction. A rotating member provided with a paddle shape and a disc-shaped flange member having an outer dimension of 24 mm provided at both ends of the rotating member.

  The specifications of the rotating member PE are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 440 mm (however, the stirring portion 1A is 110 mm, the stirring portion 1B is 330 mm), the pitch of the spiral ribs (p): 30 mm, spiral Rib thickness: 1 mm, radial length of plate-like rib (t): 3 mm, plate-like rib arrangement: 4 equally distributed locations, plate-like rib thickness: 1 mm, radial length of notch Length (t): 5 mm, circumferential length of the notch (U): 2 mm, notch location: 4 locations per pitch (equal spacing)
(Rotating member WG)
As the stirring portion 1A, a first stirring portion configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member shown in FIG. 2 and a spiral rib (left-handed) including a plate-like rib shown in FIG. 7 as the stirring portion 1B, and when viewed in the overall developer conveyance direction. Four flat blade members are provided on the outer peripheral surface of the shaft member with a length of 30 mm on the downstream side so as to extend outward in the radial direction to form a paddle shape, and a circular shape having an outer dimension of 24 mm at both ends of the rotating member. A rotating member having a plate-like flange member.

  The specifications of the rotating member WG are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 440 mm (however, the stirring portion 1A is 110 mm and the stirring portion 1B is 330 mm), and the plate-like member constituting the first stirring portion is attached to the shaft. Angle (α1): + 45 °, Mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring unit: -45 °, plate-like member thickness: 1 mm, plate-like member arrangement pitch: 25 mm, spiral Pitch of ribs (p): 30 mm, Thickness of spiral ribs: 1 mm, Radial length (h) of plate ribs (vertical blades): 8 mm, Axial length of plate ribs (W ): 3 mm, plate-like rib arrangement: one per pitch (center position between screw pitches), plate-like rib thickness: 1 mm
(Rotating member XG)
As shown in FIG. 11, as the stirring portion 1 </ b> A, a first stirring portion configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member And the second stirrer, and on the outer peripheral edges of the plate-like members constituting the first stirrer and the second stirrer, at four positions equidistant in the circumferential direction. A plate-like rib extending in the direction and having a spiral rib (left-handed) including the plate-like rib shown in FIG. 7 as the stirring portion 1B, and a developer Four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the overall conveying direction to extend radially outward to form a paddle shape, and both ends of the rotating member A disc-shaped flange member with an outer dimension of 24 mm is provided on the part. Configuration and the rotating member.

  The specifications of this rotating member are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis excluding shaft portion: 440 mm (however, stirring portion 1A is 110 mm, stirring portion 1B is 330 mm), relative to the axis of the plate-like member constituting the first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate member constituting the second stirring section: −45 °, plate member thickness: 1 mm, plate member arrangement pitch: 25 mm, Spiral rib pitch (p): 30 mm, spiral rib thickness: 1 mm, radial length (h) of plate-like rib (vertical blade): 8 mm, axial length of plate-like rib ( W): 3 mm, plate-shaped rib arrangement: 1 per pitch (center position between screw pitches)
<Experimental example 1>
[Create developer]
In accordance with the configuration shown in FIGS. 2 to 4, developing devices 1 to 7 according to the present invention in which the first stirring member, the second stirring member, the third stirring member, and the like were constituted by the rotating members shown in Table 1 were produced.

  Further, the stirring portion 1A of the first stirring member is eliminated, and the developer transport capability is configured to be substantially the same as the transport capability of the second stirring member, except that the third stirring member is not provided. Comparative developing devices 8 to 17 having the same configuration as those shown in FIG. 1 and constituted by rotating members selected according to the combinations shown in Table 1 below were produced.

  Further, the developing devices 18 to 21 according to the present invention provided with the developer supply / recovery member are manufactured, and the developing devices 22 and 23 for comparison in a mode having the developer supply / recovery member but not having the third stirring member HA. Was made.

  The developer carrying member (developing sleeve) has an outer diameter of 30 mm and an axial length of 330 mm (magnetic brush forming width of 320 mm).

  In each of the developing devices according to the present invention, the toner supply port is formed at a position where the stirring portion 1A of the first stirring member and the third stirring member face each other (when viewed in a cross section perpendicular to the longitudinal direction) It is an upper position in the middle) and is a position 15 mm downstream from the upstream end edge in the developer transport direction by the third stirring member.

  On the other hand, the formation position of the toner supply port in each of the developing devices for comparison is the same position as the toner supply port position of the developing device according to the present invention, although the third stirring member is not provided.

  As the developer, any one of the developers related to yellow toner, magenta toner, cyan toner and black toner is a two-component developer having a toner concentration of 7 mass%, and 850 g is used for developing devices 1 to 7. The developing devices 8 to 17 for comparison were filled with 750 g, the developing devices 18 to 21 were filled with 1100 g, and the developing devices 22 and 23 were filled with 1000 g of developer.

  Each of the above toners has a volume average particle diameter of 4.5 ± 0.15 μm, a CV value [a / b × 100%] indicated by the standard deviation (a) of the particle diameter distribution and the average particle diameter (b). In each color polymerized toner having a toner particle size of 18 ± 2%, large particle size silica 0.8% by mass, small particle size silica 0.2% by mass, large particle size titania 0.2% by mass, and small particle size titania 0.4%. A material obtained by externally adding mass% and calcium stearate 0.05 mass% was used.

  In any of the developers related to the toner, the carrier has a volume average particle diameter of 25 μm and a saturation magnetization of 60 emu / g on the surface of the ferrite particles, and the coating amount of the acrylic resin on the ferrite particles is 3 mass. What was coated in a state of%.

  Each of the developing devices 1 to 23 is mounted on an appropriate driving machine, and the rotation amounts of the first stirring member, the second stirring member, the third stirring member, and the developer supply / recovery member are set as shown in Table 1 below. The developer transfer amount was measured.

  The results are shown in Table 1 below.

  The developer movement amount is measured by measuring the weight of the developer discharged per unit time from the developer discharge port provided on the bottom surface of the housing on the downstream side of the second stirring member in the developer transport direction. It was.

  The “movement direction in the first / third counter part” indicates the circumferential movement direction of the two agitating members when the first agitating member and the third agitating member are viewed at the close opposing positions.

  Further, for example, two types of rotation speeds of the stirring members in the developing devices 11 to 17 are displayed. 400 rpm is the rotation speed in color image formation, and 650 rpm is the rotation speed used in monochrome image formation, which will be described later. Related to Tables 2 and 3.

[Image forming apparatus]
According to the configuration shown in FIG. 1, an image forming apparatus for forming a color image on which each of the developing devices 1 to 26 is mounted was manufactured, and an image output test was performed under the following image forming conditions.

The image forming conditions were set to be the same for all of the image forming units related to the respective color toner images.
<Image forming conditions>
-Process speed (V): 220 mm / sec (number of images formed per minute is 50 sheets)-Number of rotations of developer carrier (developing sleeve): adjusted within the range of 210 to 280 rpm on the photosensitive drum The toner adhesion amount (M) per unit area was 0.4 mg / cm ² .

-The closest distance between the photosensitive drum and the developing sleeve: 0.3 mm
Development bias: bias in which an AC bias (AC) component and a DC bias (DC) component are superimposed AC bias component: Vac = 1 kVpp, fac = 5 kHz, waveform = sine wave DC bias component: maximum exposure portion on the photosensitive drum In accordance with the detection result of the surface potential VL, control was performed so that Vdc = VL−500V.

・ Developer transport amount by developing sleeve: 25 ± 2 mg / cm ²
-Magnetic brush formation width in the axial direction of the developing sleeve: 320 mm
Toner replenishment control: a toner concentration sensor (permeability sensor) is provided at a position 80 mm upstream from the downstream edge in the overall developer conveying direction in the first agitating member, and a toner replenishment motor according to the detection result The drive was controlled.

-Toner replenishment speed: Max. 30 g / min
Photoconductor surface potential: Maximum exposed portion potential (VL): -50V to -100V
Charging potential (VH): Control was performed so that VH = Vdc−150 V in accordance with the set value of the DC bias component in the developing bias.

In the image output test, the image output of the following (1) to (6) is repeated four times (A4 × 2000 in total), the presence / absence of fogging of the character / line pattern, the presence / absence of character scattering, the density of the solid pattern The presence / absence of unevenness and the presence / absence of in-machine contamination were evaluated based on the following evaluation criteria. The results are shown in Table 2 below.
(1) Cyan (C) monochromatic characters / lines + halftone (10 steps) pattern (printing rate 30%) are output in succession 50 sheets.
(2) Cyan (C) single color solid pattern (printing rate 80%) is output continuously 150 sheets.
(3) Cyan (C) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets. (4) Blue (magenta (M) + cyan (C)) single-color character / line + halftone (10 steps) pattern (printing rate of 30% for both M and C) is output in 50 sheets.
(5) Continuous output of 150 solid blue solid patterns (printing rate of 80% for both M and C). (6) Output 50 sheets of blue (magenta (M) + cyan (C)) single color characters / line patterns (printing rate 7% for both M and C) continuously.
<Evaluation criteria>
(B) Image cover:
For image fogging, the relative reflection density of the white portion of the character / line pattern when the reflection density of unused paper is 0 is measured. If the relative reflection density is 0.004 or less, “○” is given. The case where the reflection density exceeded 0.004 and was 0.006 or less was evaluated as “Δ”, and the case where the relative reflection density exceeded 0.006 was evaluated as “x”.
(B) Letter scattering:
For character scattering, the sharpness of the character outline and the state of the bleeding of the character when the 4-point “bell” character was observed in an enlarged manner were evaluated.

If the space of the “bell” character is clearly removed and the outline of the character is clear, and the toner scattering around the character is extremely small, the space portion of the “bell” and “bell” character If the toner is slightly crushed (slightly filled with toner scatter), but the toner scatter around the character is small, the space part of the letter “△” or “bell” is crushed (filled with toner scatter). In addition, the case where there is a lot of toner scattering around the character and the outline of the character is blurred is defined as “X”.
(C) Image density unevenness:
The image density unevenness was evaluated by the color difference (distance in the L * a * b * space) at any nine positions in the page of the solid pattern of cyan single color or the solid pattern of blue single color.

“○” indicates that the color difference at 9 locations for the solid pattern of cyan single color is 3 or less and 9 color differences at the solid pattern of blue color is 7 or less, 9 locations for the solid pattern of cyan single color The color difference of 3 is more than 3 and 5 or less, and the color difference of 9 places for blue solid pattern is 7 or less, or the color difference of 9 places for cyan solid pattern is 3 or less In addition, the color difference at 9 locations for the solid pattern of blue single color exceeds 7 and 9 or less is “△”, the color difference at 9 locations for the solid pattern of cyan single color exceeds 3 and the color difference of blue single color A case where the color difference at 9 locations of the solid pattern exceeded 9 was designated as “x”.
(D) In-flight dirt:
In-machine contamination was evaluated by removing the developing device after image output and visually observing the state of contamination near the developing device mounting portion.

  When no in-machine dirt is observed, or when only a slight amount of dirt is seen only on the developing device mounting portion, “○” is indicated, and slight staining is recognized near the developing device mounting portion (for example, both ends). The case was marked with “△”, and the case where the stain on the developing device mounting part was extended to the peripheral part (for example, a charger) was marked with “x”.

  The results are shown in Table 2. The developing device numbers in the table correspond to the developing device numbers in Table 1, which also correspond to the image forming device numbers described above.

  However, in the developing device numbers 11 to 17, as described above, the rotational speed of the rotating member is 400 rpm.

<Experimental example 2>
[Production of development device]
In each of the developing devices 1 to 23 used in Experimental Example 1, a recycled toner supply port was formed on a cover corresponding to a position 8 mm upstream from the toner supply port in the developer transport direction by the third stirring member. Development devices 1 to 23 (development device numbers in all tables are unified for easy understanding of correspondence) were prepared.

  In the configuration shown in FIG. 12, the image forming apparatuses 1 to 23 for forming a monochrome image having toner recycling means mounted on each of the developing devices were manufactured.

  The toner recycling unit is configured by a conveyance unit for conveying the recycled toner to the developing device, and a toner conveyance amount per unit time is 30 g / min at the maximum.

  Then, the process speed of the image forming apparatus is set to 320 mm / sec (the number of image forming sheets per minute is 65 sheets), and the rotation speed of the developing devices 1 to 10 is set to 400 rpm. The rotation speed of the first and second stirring members was 650 rpm, and the rotation speed of the developing devices 18 to 23 was 400 rpm.

  Under the same image forming conditions as the image forming unit related to the black (BK) toner image of Experimental Example 1, the following (7) to (9) image output is repeated 8 times (A4 × 2000 sheets in total) Based on the above-mentioned evaluation criteria, the presence or absence of occurrence of unevenness in the solid pattern image density is evaluated based on the above-mentioned evaluation criteria. Was evaluated based on the following evaluation criteria.

The results are shown in Table 3 below.
(7) Black (BK) single color characters / lines + halftone (10 steps) pattern (print rate 30%) are output in succession 50 sheets.
(8) Continuously output 150 black (BK) solid patterns (printing rate 80%).
(9) Black (BK) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets.
<Evaluation criteria>
The image density unevenness is measured by measuring the relative reflection density at any nine locations in the black solid pattern page, the relative reflection density at all locations is 1.3 or more, and the difference between the maximum value and the minimum value is 0. 0.1 or less, “◯”, the relative reflection density minimum value is 1.2 or more and less than 1.3, and the difference between the maximum value and the minimum value is 0.1 or less “△” “,” When the minimum value of the relative reflection density is less than 1.2 or the difference between the maximum value and the minimum value exceeds 0.15.

  As is apparent from the above results, according to the image forming apparatus of the present invention, even when a developer in which a large amount of toner is consumed and toner replenishment including recycled toner is repeatedly used is used. Sufficient charge rising characteristics can be obtained.

  Further, it is possible to suppress the occurrence of image defects such as image fogging, character scattering, and image density unevenness, and to reduce the occurrence of in-machine contamination due to toner scattering, thereby forming a high quality image.

  On the other hand, in the comparative image forming apparatus, at least one problem of image fogging, character scattering, image density unevenness, and in-machine contamination has occurred, and it is difficult to reliably obtain a high-quality image. It is.

  In particular, in an image forming apparatus (Experimental Example 2) equipped with a toner recycling means, the rotation speed of the rotating member is increased to obtain a sufficient developer moving speed, thereby suppressing the occurrence of uneven image density in the axial direction. In such a configuration, the output torque could not be obtained because the image output test had to be stopped due to a significant increase in the stirring torque. As a result of investigating the cause, it was confirmed that the developer started to be fused to the shaft portion.

1 is a schematic diagram illustrating a first embodiment of an image forming apparatus according to the present invention. 1 is a plan view showing a first embodiment of a developing device according to the present invention. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is a schematic diagram which shows the 1st example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is the schematic which shows 2nd Embodiment of an image forming apparatus. FIG. 4 is a schematic diagram of a developing device for explaining a positional relationship between a toner supply port and a recycled toner supply port. It is a schematic diagram which shows the other example of a stirring member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Image reading part 3 Image forming part 4 Belt unit 5 Paper feed part 6 Reverse discharge / re-feed part 8 Developing device 800 Developer carrier 803 1st stirring member 805 2nd stirring member 807 3rd Stirring member 809 Developer supply / recovery means 810 Housing 812 Cover 813 Toner supply port 850 Spiral rib 855, 856, 858 Plate-shaped rib

Claims (9)

A developer carrier that carries and conveys a developer including toner and a carrier; and a side that is close to the developer carrier and adjacent to the longitudinal direction of the developer carrier, and the developer is disposed in a predetermined direction. A first agitating member that agitates while being conveyed, and a side far from the developer carrying member, adjacent to the longitudinal direction of the first agitating member, and the developer by the first agitating member A second stirring member that stirs the developer while transporting the developer in a direction opposite to the transport direction, and a housing that rotatably supports the developer carrier, the first stirring member, and the second stirring member. A developing device comprising a cover provided on an upper portion of the housing and configured to circulate and convey the developer by the first stirring member and the second stirring member;
A configuration in which the first stirring member and the second stirring member are extended to a side corresponding to the upstream side in the developer transport direction by the second stirring member and protrude from an end portion of the developer carrier. And
The first stirring member is provided in the protruding region and has a developer transport capability lower than that of the second stirring member, and the developer is in the same direction as the developer transport direction by the second stirring member. And a stirring portion 1B that has substantially the same developer transport capability as the second stirring member and that transports the developer in a direction opposite to the developer transport direction by the second stirring member. In addition,
The third stirring member has a higher developer transport capability than the second stirring member and stirs while transporting the developer in the direction opposite to the transport direction of the second stirring member. While being disposed facing the part 1A,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
A toner supply port for supplying toner is provided on the cover in a region corresponding to the upstream side when the stirring portion 1A and the third stirring member are opposed to each other and viewed in the developer transport direction by the third stirring member. Provided
A developing device. A developer carrier that carries and conveys a developer including toner and a carrier; and a side that is close to the developer carrier and adjacent to the longitudinal direction of the developer carrier, and the developer is disposed in a predetermined direction. A first agitating member that agitates while being conveyed, and a side far from the developer carrying member, adjacent to the longitudinal direction of the first agitating member, and the developer by the first agitating member A second stirring member that stirs the developer while transporting the developer in a direction opposite to the transport direction, and a housing that rotatably supports the developer carrier, the first stirring member, and the second stirring member. A developing device comprising a cover provided on an upper portion of the housing and configured to circulate and convey the developer by the first stirring member and the second stirring member;
A configuration in which the first stirring member and the second stirring member are extended to a side corresponding to the upstream side in the developer transport direction by the second stirring member and protrude from an end portion of the developer carrier. And
While configuring the second stirring member with a spiral rib,
The first stirring member is provided in the protruding region, has a helical rib and a plate-like rib provided in the rotation axis direction, and is lower than the second stirring member. 1 A of stirring parts which convey a developer in the same direction as the conveyance direction by the said 2nd stirring member with conveyance capability, and a spiral rib, and have the developer conveyance capability substantially the same as the said 2nd stirring member The second stirring member includes a stirring portion 1B that transports the developer in a direction opposite to the transport direction by the second stirring member, and further has a developer transport capability higher than that of the second stirring member. A third agitating member that conveys the developer in a direction opposite to the conveying direction by the above-described agitating portion 1A,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device. A developer carrier that carries and conveys a developer including toner and a carrier; and a side that is close to the developer carrier and adjacent to the longitudinal direction of the developer carrier, and the developer is disposed in a predetermined direction. A first agitating member that agitates while being conveyed, and a side far from the developer carrying member, adjacent to the longitudinal direction of the first agitating member, and the developer by the first agitating member A second stirring member that stirs the developer while transporting the developer in a direction opposite to the transport direction, and a housing that rotatably supports the developer carrier, the first stirring member, and the second stirring member. A developing device comprising a cover provided on an upper portion of the housing and configured to circulate and convey the developer by the first stirring member and the second stirring member;
A configuration in which the first stirring member and the second stirring member are extended to a side corresponding to the downstream side in the developer transport direction by the first stirring member, and protrude from the end of the developer carrier. And
While configuring the second stirring member with a spiral rib,
The plurality of plate-like members provided in the first region and the plurality of plate-like members provided in the first direction and provided in the first direction, and provided in the second direction. A stirring portion 1A that has a lower plate-shaped member, has a lower developer conveying ability than the second agitating member, and conveys the developer in the same direction as the conveying direction by the second agitating member, and a spiral shape And a stirring portion 1B that transports developer in the direction opposite to the transport direction of the second stirring member, and has substantially the same developer transport capability as the second stirring member. ,
A third agitating member that has a higher developer conveying capability than the second agitating member and conveys the developer in a direction opposite to the conveying direction by the second agitating member is disposed opposite the agitating portion 1A. As well as
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device. The peripheral surface of the developer carrying member and the first agitating member move in directions opposite to each other when viewed at their opposing proximity points. Development device. A rotatable developer supply / recovery member is provided between the developer carrier and the first agitating member, and the peripheral surfaces move in directions opposite to each other when viewed from the opposing proximity of both. The developing device according to claim 1. When the volume average particle diameter of the toner is Dt [μm] and the volume average particle diameter of the carrier is Dc [μm],
Dt = 3-5
Dc = 5 · Dt ~ 10 · Dt
The developing device according to claim 1, wherein a developer including a toner and a carrier is used. An image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image into a toner image.
While using the developing device of any one of Claims 1 thru | or 6 as said image development means,
The moving speed of the image carrier is V [mm / sec], the maximum adhesion amount per unit area of the toner image formed on the image carrier is M [mg / cm ² ], and the direction orthogonal to the moving direction of the image carrier The maximum width of the toner image is L [mm], the developer movement amount in the rotation axis direction of the developer carrier by the second stirring member is W [g / sec], and the rotation speed of the second stirring member is R [rpm]. When
W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus. An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier A transfer unit that transfers the image to a transfer material or an intermediate transfer member; a cleaning unit that cleans the surface of the image carrier after the transfer; and a toner that is removed from the surface of the image carrier by cleaning is supplied to the developing unit. In an image forming apparatus having toner recycling means for recycling,
The developing device according to any one of claims 1 to 6 is used as the developing unit, and the position is on the cover of the developing device and between the stirring portion 1A and the third stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner. 9. The image forming apparatus according to claim 8, wherein the recycled toner supply port is located upstream of the toner supply port in the developer transport direction of the third stirring member.

Images