JP2005077976A - Development device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development device and an image forming apparatus having a new configuration which can impart a specified charge amount to the toner, without decreasing the carrying speed of a developer, while having a simple configuration and which can form high quality images of. <P>SOLUTION: The development device has a configuration that a developer is circulated and carried by a first stirring member, a second stirring member and a third stirring member disposed facing a part of the second stirring member, and has a configuration that the toner to be replenished to the facing part of the second and third stirring members via a toner supply port disposed on the cover of the housing is submerged into the developer by rotation of the second and third stirring members, rotated in such a manner that each circumference face is made to move downward from the upper side. The image forming apparatus is equipped with the above developing device. <P>COPYRIGHT: (C)2005,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 after being developed once is inferior to the 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.

Many techniques for improving the stirring efficiency of the developer have been proposed in order to cope with such a problem. For example, by providing a member that functions as an auxiliary stirring member in the stirring means, a configuration having a high developer conveying capability. (For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3).
Japanese Patent Laid-Open No. 7-13420 JP-A-9-166918 Japanese Patent Laid-Open No. 9-288212

  However, any of the developing devices disclosed in the above-mentioned patent documents can improve the stirring efficiency of the developer, but on the other hand, since the circulating transport speed of the developer in the developing device is reduced, for example, As a developing device used for an image forming apparatus having a high process speed, there still seems to be room for improvement.

  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, there is a problem that image density unevenness tends to occur and it is 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.

(1) a developer carrying member for carrying and conveying a developer including toner and a carrier, a side close to the developer carrying member and facing the longitudinal direction of the developer carrying member; A first stirring member that stirs while transporting the toner in a predetermined direction, and is provided on the side far from the developer carrying member and opposed to the longitudinal direction of the first stirring member. Provided between the second stirring member that stirs the developer while transporting the developer in the direction opposite to the developer transport direction, and between the developer carrier and the first stirring member, and supplies the developer to the developer carrier. And a developer supply and recovery member that recovers the developer removed from the developer carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply and recovery member. A housing that is pivotally supported and accommodated, and the housing. In the developing apparatus having a cover which is provided over the grayed,
The first agitating member and the second agitating member are extended to a side corresponding to the downstream side in the developer conveying direction by the first agitating member and protrude from the end of the developer carrier. With
The second agitating member is provided on the downstream side in the developer conveying direction by the first agitating member, and has a stirring portion 2A having a developer conveying ability lower than that of the first agitating member, and the first agitating member. A stirring portion 2B provided on the upstream side in the developer transport direction and having substantially the same developer transport capability as the first stirring member;
A third agitating member having a developer conveying capability substantially the same as or lower than that of the agitating part 2A and agitating while conveying the developer in the same direction as the developer conveying direction by the agitating part 2A; While arrange | positioning facing 2 A of stirring parts of a 2nd stirring member,
When the stirring portion 2A of the second stirring member and the third stirring member are viewed at their opposing proximity points, the rotation direction is determined such that the peripheral surface moves in the forward direction from the top to the bottom, and
A region between the shafts of the region where the stirring portion 2A of the second stirring member and the third stirring member are opposed to each other, the region corresponding to the upstream side in the developer transport direction by the third stirring member. A toner supply port for supplying toner is provided on the cover.
A developing device.

(2) a developer carrying body for carrying and conveying a developer containing toner and a carrier, a side close to the developer carrying body, and provided facing the longitudinal direction of the developer carrying body; A first stirring member that stirs while transporting the toner in a predetermined direction, and is provided on the side far from the developer carrying member and opposed to the longitudinal direction of the first stirring member. Provided between the second stirring member that stirs the developer while transporting the developer in the direction opposite to the developer transport direction, and between the developer carrier and the first stirring member, and supplies the developer to the developer carrier. And a developer supply and recovery member that recovers the developer removed from the developer carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply and recovery member. A housing that is pivotally supported and accommodated, and the housing. In the developing apparatus having a cover which is provided over the grayed,
The first agitating member and the second agitating member are extended to a side corresponding to the downstream side in the developer conveying direction by the first agitating member and protrude from the end of the developer carrier. With
The first stirring member is constituted by a spiral rib provided around the rotation axis, and
The second agitating member is provided on the downstream side in the developer conveying direction by the first agitating member, and has a spiral rib provided around the rotation axis and a plate-like rib extending in the rotation axis direction. A part 2A and a stirring part 2B provided on the upstream side in the developer conveying direction by the first stirring member and having a spiral rib provided around the rotation axis; and
A third agitating member having a developer conveying capability substantially the same as or lower than that of the agitating part 2A and agitating while conveying the developer in the same direction as the developer conveying direction by the agitating part 2A; While arrange | positioning facing 2 A of stirring parts of a 2nd stirring member,
When the stirring portion 2A of the second stirring member and the third stirring member are viewed at their opposing proximity points, the rotation direction is determined such that the peripheral surface moves in the forward direction from the top to the bottom, and
The region between both shafts of the region where the stirring portion 2A of the second stirring member and the third stirring member are opposed to each other, in the region corresponding to the upstream side in the developer transport direction by the third stirring member. A toner supply port for supplying toner is provided on the cover.
A developing device.

(3) a developer carrying member for carrying and conveying a developer containing toner and a carrier, a side close to the developer carrying member and facing the longitudinal direction of the developer carrying member; A first stirring member that stirs while transporting the toner in a predetermined direction, and is provided on the side far from the developer carrying member and opposed to the longitudinal direction of the first stirring member. Provided between the second stirring member that stirs the developer while transporting the developer in the direction opposite to the developer transport direction, and between the developer carrier and the first stirring member, and supplies the developer to the developer carrier. And a developer supply and recovery member that recovers the developer removed from the developer carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply and recovery member. A housing that is pivotally supported and accommodated, and the housing. In the developing apparatus having a cover which is provided over the grayed,
The first agitating member and the second agitating member are extended to a side corresponding to the downstream side in the developer conveying direction by the first agitating member and protrude from the end of the developer carrier. With
The first stirring member is constituted by a spiral rib provided around the rotation axis, and
The second agitating member is provided on the downstream side in the developer conveying direction by the first agitating member, and has a stirring portion 2A having a developer conveying ability lower than that of the first agitating member, and the first agitating member. A stirring portion 2B provided on the upstream side in the developer transport direction and having substantially the same developer transport capability as the first stirring member;
Stirring while transporting the developer in the same direction as the developer transport direction by the stirring portion 2A, comprising a semi-elliptical plate-like member arranged in an inclined manner in the first direction and the second direction with respect to the rotation axis. A third agitating member is disposed opposite the agitating portion 2A of the second agitating member, and
When the stirring part 2A of the second stirring member and the third stirring member are viewed at their opposing proximity points, the rotation direction is determined such that the peripheral surface moves in the forward direction from the top to the bottom,
A region between the shafts of the region where the stirring portion 2A of the second stirring member and the third stirring member are opposed to each other, the region corresponding to the upstream side in the developer transport direction by the third stirring member. A toner supply port for supplying toner is provided on the cover.
A developing device.

  (4) Any one of (1) to (3) above, wherein the developer carrying member and the developer supply / recovery member have their peripheral surfaces moving in directions opposite to each other when viewed from their proximity points. The developing device described in one.

(5) 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 any one of (1) to (4), wherein a developer containing a toner and a carrier is used.

(6) 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. In
As the developing unit, the developing device according to any one of (1) to (5) is used,
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 first stirring member is W [g / sec], and the rotation speed of the first stirring member is R [rpm]. When W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus.

(7) 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 the image carrier Transfer means for transferring the toner image on the transfer material or intermediate transfer body, cleaning means for cleaning the surface of the image carrier after transfer, and toner removed from the surface of the image carrier by cleaning to the developing means In an image forming apparatus having toner recycling means for supplying and recycling,
The developing device according to any one of (1) to (5) is used as the developing unit, and the stirring portion 2A and the third stirring member are opposed to each other on a cover of the developing device. An image forming apparatus, wherein a recycled toner supply port for supplying recycled toner is provided at a position corresponding to an inter-axis portion between the two areas.

  (8) The image forming apparatus according to (7), wherein the recycled toner supply port is located upstream of the toner supply port in the developer transport direction by the third stirring member.

  According to the developing device having the above configuration, for example, while the developer is mainly stirred by two stirring members (first stirring member and second stirring member), the developer is circulated and conveyed in the direction of the rotation axis of the developer carrier, and the developer. Therefore, a sufficient agitation time can be secured without reducing the developer conveying speed or the conveying amount.

  Then, since the toner in the developer is supplied to the developer carrier in a state where the toner has a desired charge amount, it is possible to suppress the occurrence of fogging and toner scattering due to poor charging of the toner. Even so, high image quality can be maintained.

  In addition, a third stirring member is provided opposite to a part of the second stirring member in the longitudinal direction, and the two stirring members are viewed at their opposing proximity points. Since it is configured to move in the forward direction and to replenish the toner from the upper side corresponding to the opposing portion, the sinking of the replenished toner into the developer can be accelerated.

  In other words, uniform replenishment of the replenishment toner in the developer can be quickly performed, so that the stirring of the toner during the circulation conveyance can be further promoted, and the intended charge amount can be easily given to the toner. .

  Further, since the axial length of the third stirring member may be shorter than the axial length of the second stirring member, for example, the developing device can be kept small for the effect to be achieved. Furthermore, since the container for storing the replenishing toner provided on the image forming apparatus main body side and the lower space in which 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 occurrence of toner scattering, fogging, image density unevenness and the like can be suppressed as much as possible, and high-quality images 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 includes an automatic document feeder 1 at the top of the apparatus main body, and includes an image reading unit 2, an image forming unit 3, a belt setting unit for the belt unit 4, and a paper feeding unit. 5, a fixing device T, a reverse discharge / refeed unit 6, and an ADU 7 as reverse transfer 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 forms four image forming units (hereinafter referred to as image forming units) of yellow (Y), magenta (M), cyan (C), and black (BK) that form a toner image corresponding to a color separation image. ) 30.

  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. A scorotron charger 320, an exposure optical system 330 as image writing means, a developing device 8 for developing an electrostatic latent image, a transfer means 340, and a blade for cleaning the surface of the photosensitive drum 310 after transfer (cleaning) The main component is a cleaning device 350 including the means.

  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. A developer carrying member (developing sleeve) having a rotatable and non-magnetic cylindrical shape incorporating a magnet in which the magnets are arranged is described in detail later.

  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 the 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 device 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.

  In transferring, an appropriate transfer bias voltage is applied between the transfer roller 510 and the backup roller 410.

  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 trailing edge of the paper P in the traveling direction being nipped 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 this specification, the left-right direction in FIG. 2 is referred to as “front-rear direction”, and the up-down direction in FIG. 2 is referred to as “axial direction”, “rotational axis direction”, or “longitudinal direction”. Further, the vertical direction in FIGS. 3 and 4 is expressed as “vertical direction”.

  The developing device 8 includes a developer carrying member (developing sleeve) 800 carrying and transporting the developer, and a position closer to the developer carrying member 800 (front side), in the longitudinal direction of the developer carrying member. A first agitating member 803 that agitates while conveying the developer in a predetermined direction, and is located on the far side (rear side) with respect to the developer carrier, and the first agitating member A second stirring member 805 that stirs the developer while transporting the developer in the direction opposite to the developer transport direction by the first stirring member 803, the developer carrier 800, and the first carrier. 1 is provided between the agitating member 803 and supplies the developer to the developer carrying member 800 and removes the developer removed from the developer carrying member 800 (hereinafter simply referred to as a supply collecting unit). From 815 to developer storage stirring section Hereinafter, a developer supply / recovery member 809 to be recovered in 816 (hereinafter simply referred to as a storage agitation unit), and a rotation member such as the developer carrier, the first agitation member, the second agitation member, and the developer supply / recovery member Are housed in parallel and in a rotatable manner, and a cover 812 provided on the top 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.

  Then, by positioning one end position of both agitating members in substantially the same plane as the end position of the developer carrier 800, the end of the developer carrier 800 together with the housing 810 on the other side. It protrudes more than.

  In other words, the first agitating member 803 extends and protrudes downstream in the developer conveyance direction. Reference numeral 802 indicates a protruding region.

  In addition, the developing device 8 includes a third stirring member 807, and the third stirring member is opposed to the second stirring member 805 in the protruding region 802 and is rotatable to a position outside the second stirring member. Is provided.

  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 hold the developer on the developer carrier and remove the developer from the developer carrier 800 using a repulsive magnetic field. It is configured as follows.

  As described above and as shown in FIG. 3, the developer carrier 800 and the developer supply / recovery member 809 are housed in a developer supply / recovery unit 815 formed in the housing 810. The first stirring member 803, the second stirring member 805, and the third stirring member 807 are accommodated in the space communicating with the supply and recovery unit 815 without a partition wall, that is, in the developer storing and stirring unit 816.

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

  The rotating member such as the stirring member receives power from a drive system provided on the image forming apparatus main body side, and is configured to rotate in the direction of the arrow through a gear or the like. However, a known technology is used for the power transmission mechanism. it can.

  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 counterclockwise.

  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 addition, since the second stirring member 805 and the third stirring member 807 are axially rotated so that their peripheral surfaces move from the upper side to the lower side at the opposing proximity point, as described later, for example, replenishment is performed. The toner can be quickly dispersed in the developer.

  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.).

  Now, based on the developer conveying capability of the first agitating member 803, the second agitating member 805 is on the downstream side in the developer conveying direction by the first agitating member 803 (here, the protruding region 802 is indicated). The developer is transported in a first direction (in the direction opposite to the transport direction by the first stirring member, in the drawing, from the lower side to the upper side in the drawing) with a transport capability lower than that of the first stirring member. The agitating part 2A to be conveyed and the agitating part 2B that is located upstream in the developer conveying direction by the first agitating member 803 and conveys the developer in the first direction with substantially the same conveying ability as the first agitating member 803. And have.

  The third agitating member 807 conveys the developer in the same direction as the conveying direction by the second agitating member with a conveying ability substantially the same as or lower than the agitating portion 2A of the second agitating member 805. To do.

  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 first stirring member 803 and the second stirring member 805 are plate-like blade members that project radially outward from the circumferential surface of the rotating shaft at the downstream end when viewed in the developer transport direction by each rotation. 2 at a position indicated by reference numerals 820 and 821 in FIG. 2, a developer delivery portion is formed between the first and second stirring members 803 and 805 so that the developer is smoothly circulated.

  According to the developing device having the above-described configuration, the developer in the storage agitation unit 816 is conveyed in the axial direction indicated by the arrow while being agitated by the rotation of the second agitation member 805, and the first agitation is performed via the transfer unit 820. 1 The stirring member 803 is affected.

  While being agitated as the first agitating member 803 is rotated, the developer conveyed in the direction opposite to the conveying direction by the second agitating member 805 is sequentially supplied to the developer carrier 800 via the developer supply / recovery member 809. Supplied.

  On the other hand, the developer that has been removed from the developer carrier 800 and has been subjected to the action of the developer supply / recovery member 809 is transported in the axial direction indicated by the arrow by the first agitating member 803, and is passed through the delivery portion 821. The second agitating member 805 is acted on, and further, after being branched and agitated by the second agitating member 805 and the third agitating member, they join together and repeat the above-described behavior.

  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 is provided between the stirring part 2A of the second stirring member 805 and the third stirring member 807 (as shown in the sectional view of FIG. 4, the second stirring member 805 (stirring part 2A)). And the third agitating member 807 are in the middle of the portions facing each other, that is, the region sandwiched between the shafts of the both), and an appropriate position on the upstream side in the developer conveyance direction by the third agitating member Are provided on the cover 812 corresponding to.

  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 2A and the third stirring member 807 is short. It is.

  Therefore, when the stirring portion 2A has a sufficient length, it is not necessary to be upstream, but even in that case, the new toner is uniformly dispersed in the developer, the charge amount is given by the developer friction, and the like. Is considered to be upstream.

  The supplied toner is efficiently stirred with the developer by the rotation of the stirring portion 2A and the third stirring member 807.

  That is, the stirring part 2A and the third stirring member 807 of the second stirring member 805 are rotated so 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 2A of the second stirring member 803 and the third stirring member 807, and new toner is replenished depending on the rotation direction of the second stirring member and the third stirring member. Even in such a case, the toner can be dispersed and the charge rising can be performed satisfactorily, and further, the developer stirring ability of the third stirring member 807 can suppress the occurrence of the 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 with 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.

  In the above-described image forming apparatus, 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 of the image carrier [mm / sec], 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, and W is the developer movement amount in the rotational axis direction of the developer carrier by the first stirring member [g / Sec] and R indicate the rotation speed [rpm] of the first stirring member.

  When the developer movement amount (developer transport amount) W in the rotation axis direction by the first stirring member 803 is excessively small, the developer in the developer supply region on the downstream side in the developer transport direction of the first stirring member. The toner density decreases, it becomes difficult to supply a sufficient amount of toner to the development area, and unevenness in image density tends to occur.

  In addition, when the number of rotations of the first stirring member 803 is excessive, the developer is likely to be deteriorated by heat generated in the shaft portion of the first stirring member 803 and a high-quality image can be formed. It becomes difficult.

  In other words, the developer is supplied to the development area in the axial direction without toner density unevenness by performing the development process in a state satisfying the specific conditions (a) and (b) of the image forming apparatus. Therefore, an image having a uniform image density without image density unevenness can be obtained.

  In addition, by setting the number of rotations of the first stirring member to 600 rpm or less, it is possible to prevent the developer from being deteriorated by heat generated when the first stirring member is rotated at a high speed.

  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 developing 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.

  Next, a specific configuration example of the 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.

  FIG. 5 is a schematic diagram showing a first example of the agitating member, which extends over the entire circumference of the outer peripheral surface of a shaft (hereinafter also referred to as a rotating shaft) J and has a predetermined pitch (screw pitch) p and a predetermined direction in the axial direction. Thus, it is configured as a rotating member composed of a spiral rib (screw) 850 formed (shown in one direction in the figure).

  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 all the stirring members in the developing device shown in FIGS. 2 to 4 are configured by such a spiral rib, the following may be performed.

  That is, the first stirring member 803 is configured by a spiral rib in one direction having a reference pitch p, and the stirring portion 2A of the second stirring member 805 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 direction opposite to the conveyance direction by the first agitating member 803 (the second agitating member 805 and the first agitating member 803 have opposite rotation directions, so the conveying direction In order to reverse the direction, the spiral directions of both are the same direction), and the stirring portion 2B is a spiral rib having a pitch p, and the reverse direction to the conveying direction by the first stirring member 803 Further, the direction of the spiral is determined so that the developer can be transported, and the third agitating member 807 is formed at a pitch equal to or smaller than the pitch of the agitating portion 2A, and the second agitating member 805 is configured. In The direction of the spiral is determined so that the developer can be conveyed in the same direction as the conveying direction (the second agitating member 805 and the third agitating member 807 are opposite in rotation direction, so that both conveying directions are the same. To achieve the direction, the directions of the spirals of both are opposite directions).

  In the first example and other examples described below, for example, the configuration of the downstream end portion of each stirring member in the developer conveyance direction is a peripheral surface of the rotation shaft J and is plate-shaped so as to protrude radially outward. A configuration in which blades are provided to enable smooth circulation and conveyance of the developer is preferable.

  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 semi-elliptical plate-like members 851 and 852 are inclined on the outer peripheral surface of the rotation axis J in different directions at the axis center with respect to the same plane perpendicular to the rotation axis. 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 (linear shape) 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 rib 856 in the rotation axis direction is configured to be larger than the width W of the rib 855 shown in FIG. 7, but the size, the number of rows, etc. of the width W are intended. Anything can be achieved, 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 extending 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 agitating member shown in FIG. 10 rotates over the entire outer peripheral surface of the rotating shaft J and through the spiral rib 850 formed at a predetermined pitch p in the axial direction and the outer peripheral edge of the spiral rib. And plate-like ribs 858 extending linearly in the direction of the axis J. In this example, the ribs are provided at two locations (upper edge and lower edge in the figure) 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-shaped members 851 and 852 having a shape are provided to be inclined, and a plurality of such sets are arranged in the axial direction at a predetermined pitch p, and the rotation at the outer peripheral edge of the plate-shaped members 851 and 852 A plate-like rib 858 extending linearly in the direction of the 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, thereby agitating with the spiral ribs 850 and surrounding with the plate-like ribs 858 as auxiliary agitating members in the process of conveying the developer in the axial direction. Stir in the direction.

  It is desirable that the developer supply / recovery member has a configuration in which the axial conveyance capacity is substantially zero. For example, plate-like members are provided at four equal positions in the circumferential direction of the shaft. A rotating member having a configuration of a cross paddle configured as described above or a configuration in which a plurality of elliptical plates are provided on the shaft so as to perform a function of only stirring is preferable.

  Further, as the stirring portion 2B of the first stirring member and the second stirring member, a configuration having a high axial conveyance capability, for example, a rotating member having a configuration shown in FIGS. 5, 7, and 9 is preferable. Rotating members having a low axial conveyance capability as shown in FIGS. 6, 8, 10, and 11 are not preferable.

  Furthermore, as the stirring portion 2A and the third stirring member of the second stirring member, a configuration having a high stirring capability and a low conveying capability, for example, a rotating member having a configuration shown in FIGS. 6, 8, 10, and 11 is preferable. On the other hand, the rotating member having the structure shown in FIGS. 5, 7, and 9 is not so preferable.

  As an example, the configuration of the stirring portion 2A in the second stirring member is configured by a spiral rib having a plate-like rib shown in FIG. 10, and the configuration of the stirring portion 2B is configured by a spiral rib shown in FIG. be able to.

  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.

  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, the occurrence of problems such as toner scattering, fogging, and image density unevenness can be suppressed, and a higher quality image can be formed.

  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 forming a color image provided with 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 also has a recycled toner supply port to which the recycled toner conveyed by the toner recycling means is supplied. The rest is basically the same as in the first embodiment.

  In the figure, the same members (means) as the above-described members (means) are given the same reference numerals.

  In the figure, 310 is a photosensitive drum as an image carrier, 320 is a charger, 330 is an exposure optical system (image 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 transport unit 901 is built in a cylindrical outer frame 903 (shown by a two-dot chain line for the sake of convenience), and a recycle 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.

  Similar to the toner supply port 813, the recycled toner supply port 825 is an inter-axial portion of the region where the stirring portion 2A of the second stirring member 805 and the third stirring member 807 face each other. The developer is provided on the cover 812 corresponding to an appropriate position on the upstream side of the toner supply port 813 when viewed in the developer conveying direction by the two agitating members.

  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 using FIG. However, it is practically preferable to provide the recycled toner supply port 825 at an upstream position 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, it is possible to accelerate the sinking of the recycled toner, which has poor fluidity compared to the new toner and has a low chargeability, into the developer. Since the time can be lengthened, the desired charge can be obtained for the recycled toner, 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. be able to.

  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 according to the purpose.

Next, experimental examples conducted for confirming the effects of the present invention will be described.
[Production of rotating member]
The following rotating members used as the first stirring member, the second stirring member, the third stirring member, and the developer supply / recovery member were prepared.
(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 CC)
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.
(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, The length (W) in the axial direction of the plate-like rib: 12 mm, the length (t) in the radial direction of the plate-like rib: 3 mm, the thickness of the plate-like rib: 1 mm, and the attachment location of the plate-like rib: shaft Two symmetrical places (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)
A rotating member having a cross paddle structure provided with plate-like ribs (flat blade members) extending radially outward and in the longitudinal direction of the shaft from four equal parts in the circumferential direction of the shaft.

  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 portion: 360 mm, outer diameter of the shaft member: 6 mm, thickness of the plate member: 1 mm
(Rotating member L)
The rotating member LL has the same configuration as the rotating member LL except that the axial length excluding the shaft portion is 110 mm.
(Rotating member O)
In the rotating member LL, the rotating member has the same configuration as the rotating member LL except that the axial length excluding the shaft portion is 110 mm and the spiral rib is clockwise.
(Rotating member P)
In the rotating member MM, the rotating member has the same configuration as the rotating member MM except that the axial length excluding the shaft portion is 110 mm and the spiral rib is right-handed.
(Rotating member U)
In the rotating member WW, the axial length excluding the shaft portion is 110 mm, and the mounting angle of the plate-like member with respect to the shaft is (α1): −45 °, (α2): + 45 °.
A rotating member having the same configuration as the rotating member WW except for the above.
(Rotating member V)
In the rotating member XX, the axial length excluding the shaft portion is set to 110 mm, and the mounting angle of the plate-like member with respect to the shaft is (α1): −45 °, (α2): + 45 °.
A rotating member having the same configuration as the rotating member XX except for the above.
(Rotating member EA)
As the stirring portion A (1A, 2A), a spiral rib with a notch portion (left-handed) shown in FIG. 9 and a spiral rib (left-handed) shown in FIG. 5 as the stirring portion B (1B, 2B) And four flat blade members are provided on the outer peripheral surface of the shaft member that extends 30 mm downstream in the overall developer transport direction so as to extend radially outward. A rotating member having 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 EA are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 mm), outer diameter of shaft member: 6 mm, pitch of spiral rib (P): 30 mm, thickness of spiral rib: 1 mm, radial length of cutout portion (t): 5 mm, circumferential length of cutout portion (U): 2 mm, cutout portion: 4 locations per pitch ( Circumferentially equidistant)
(Rotating member FA)
The rotating member EA has the same configuration as the rotating member EA except that the pitch (p) of the spiral ribs in the stirring portion A is 20 mm.
(Rotating member HA)
As the stirring portion A (1A, 2A), a spiral rib (left-handed) including a plate-like rib shown in FIG. 7 and as the stirring portion B (1B, 2B), a spiral rib shown in FIG. (Left-handed) and four flat blade members extend radially outward on the outer peripheral surface of the shaft member extending 30 mm in length downstream in the overall developer transport direction. The rotating member is configured to have a paddle shape and a disk-shaped flange member having an outer dimension of 24 mm at both ends of the rotating member.

  The specifications of the rotating member HA are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 mm), outer diameter of shaft member: 6 mm, pitch of spiral rib (P): Stirring part A is 20 mm, stirring part B is 30 mm, thickness of spiral rib: 1 mm, radial length of plate-like rib (h): 5 mm, axial length of plate-like rib ( W): 3 mm, plate-like rib arrangement: one per pitch (center position between screw pitches), plate-like rib thickness: 1 mm
(Rotating member KA)
As a stirring part A (1A, 2A), a spiral rib (left-handed) including a plate-like rib extending in the axial direction shown in FIG. 10 and a stirring part B (1B, 2B) are shown in FIG. Four flat blade members are integrally formed on the outer peripheral surface of the shaft member having a length of 30 mm on the downstream side in the developer conveying direction as a whole. A rotating member having a configuration in which a paddle shape is provided so as to extend radially outward, and a disc-shaped flange member having an outer dimension of 24 mm is provided at both ends of the rotating member.

  The specifications of the rotating member KA are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 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, axial length of plate-like rib: 110 mm, arrangement of plate-like rib: shaft 2 positions of target, thickness of plate-like rib: 1mm
(Rotating member OC)
As the stirring portion A (1A, 2A), a spiral rib (but right-handed) shown in FIG. 10 is formed on the outer peripheral surface of the shaft member, and on the outer peripheral edge of the spiral rib, in the axial direction. A plate-like rib that extends without breaks is provided, and the stirring portion B (1B, 2B) is constituted by a spiral rib (however, right-handed) shown in FIG. Four plate-like blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the general conveying direction so as to extend radially outward, and are formed into paddle shapes. A rotating member having a configuration in which a disk-shaped flange member having an outer dimension of 24 mm is provided.

  The specifications of the rotating member OC are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 mm), spiral rib pitch (p): 30 mm, spiral Rib thickness: 1 mm, radial length of plate-like rib member (t): 5 mm, axial length of plate-like rib: 110 mm, arrangement of plate-like ribs: two axially symmetric, plate-like Rib thickness: 1mm
(Rotating member YE)
As a stirring part A (1A, 2A), a spiral rib (left-handed) including a plate-like rib extending in the axial direction shown in FIG. 10 and a stirring part B (1B, 2B) are shown in FIG. Four flat blade members on a shaft member outer peripheral surface having a spiral rib (left-handed) with a notch shown and having a downstream length of 30 mm as viewed in the overall developer conveyance direction Is formed so as to be paddle-shaped by extending outward in the radial direction, and a rotating member having a disk-shaped flange member having an outer dimension of 24 mm is provided at both ends of the rotating member.

  The specifications of the rotating member YE are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 mm), pitch of spiral rib (p): plate-like rib With a notch, 30 mm, spiral rib thickness: 1 mm, radial length of plate-like rib member (t): 3 mm, axial length of plate-like rib: 110 mm, plate-like Rib arrangement: two axially symmetric locations, plate-like rib thickness: 1 mm, radial length (t) of cutout portion: 5 mm, circumferential length of cutout portion (U): 2 mm, cutout portion: 1 pitch 4 locations per hit (equally spaced)
(Rotating member LG)
As a stirring part A (1A, 2A), a spiral rib (left-handed) including a plate-like rib extending in the axial direction shown in FIG. 10 and a stirring part B (1B, 2B) are shown in FIG. Four flat plates on the outer peripheral surface of the shaft member having a spiral rib (left-handed) including the plate-shaped rib shown and having a length of 30 mm on the downstream side in the overall conveyance direction of the developer A rotating member having a configuration in which a blade member is provided so as to extend radially outward to form a paddle shape, and a disk-shaped flange member having an outer dimension of 24 mm is provided at both ends of the rotating member.

  The specifications of the rotating member LG are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 mm), spiral rib pitch (p): 30 mm, spiral Rib thickness: 1 mm, radial length (t) of the plate-like rib extending in the axial direction: 5 mm, attachment location of the plate-like rib extending in the axial direction: two axially symmetric plate-like shapes extending in the axial direction Rib thickness: 1 mm, radial length (h) of plate-like ribs (vertical blades): 8 mm, axial length of plate-like ribs (W): 3 mm, arrangement of plate-like ribs: 1 pitch One per hit (center position between screw pitches), plate-like rib thickness: 1 mm
(Rotating member MG)
In the rotating member LG, the radial length of the plate-like ribs extending in the axial direction constituting the stirring portion A is 3 mm, and the rotating member LG is the same except that the mounting locations are four equally distributed portions in the circumferential direction. A rotating member having the same configuration as the above.

<Experimental example 1>
[Production of development device]
In accordance with the configuration shown in FIGS. 2 to 4, the developer supply and recovery member, the first stirring member, the second stirring member, and the third stirring member are constituted by rotating members shown in Table 1 below. ~ 8 were made.

  Further, for comparison of the configuration in which the second stirring member and the third stirring member selected according to the following Table 1 are rotated so that the respective peripheral surfaces move in the forward direction from the lower side to the upper side at the portions facing each other. The developing device 9 was prepared.

  Further, as shown in FIG. 14, the stirring portion 2A of the second stirring member is eliminated, and the developer transport capability is configured to be substantially the same as the transport capability of the first stirring member, and a third stirring member is provided. A comparative developing device 10-19 having the same configuration as shown in FIG. 2 except that the first stirring member was constituted by a rotating member selected according to the combination shown in Table 1 below was produced.

  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).

  The toner supply port is formed in each of the developing devices 1 to 8 and the comparative developing device 9 according to the present invention at portions where the stirring portion 2A of the second stirring member and the third stirring member face each other (longitudinal). When viewed in a cross-section perpendicular to the direction, it is an upper position in the middle of both members, and is a position 15 mm downstream from the upstream edge in the developer conveyance direction by both stirring members.

  On the other hand, in each of the developing devices 10 to 19 for comparison, the toner supply port is formed at an upper position on the rear side of the second stirring member, and an upstream edge in the developer transport direction by the second stirring member. 15 mm downstream of the position.

  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% by mass. 8 and comparative developing device 9 were filled with 1100 g, and comparative developing devices 10 to 19 were filled with 1000 g of developer.

  Each of the above toners has a volume average particle size of 4.5 ± 0.15 μm, a CV value [A / B × 100%] indicated by the standard deviation (a) of the particle size distribution and the average particle size (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 the state of% was used.

  Each of the developing devices 1 to 8 and the comparative developing devices 9 to 19 according to the present invention is attached to an appropriate driving machine, and the rotation direction and the rotation speed of the first stirring member, the second stirring member, and the third stirring member are set. The developer transfer amount was measured by setting as shown in Table 1 below.

  The developer moving amount is measured by stopping the driving of the developer carrier and the developer supply / recovery member, driving the other rotating member, and developing the developer provided on the bottom surface of the housing on the downstream side of the first stirring member in the developer transport direction. This was performed by measuring the weight of the developer discharged per unit time from the developer discharge port. The results are shown in Table 1 below.

  In Table 1, the “rotation direction” related to the first agitating member indicates the moving direction when viewed at the position close to the developer supply / recovery member.

  Further, the “movement direction in the second / third opposed portion” indicates the movement direction of both the agitating members when viewed in the proximity facing position between the second agitating member and the third agitating member.

  Further, although the rotation speeds of the first stirring members in the developing devices 13 to 19 are displayed, 400 rpm is the rotation speed in color image formation, and 650 rpm is the rotation speed in monochrome image formation. These are related to Tables 2 and 3 described later.

[Image forming apparatus]
In accordance with the configuration shown in FIG. 1, an image forming apparatus for forming a color image on which each of the developing devices 1 to 8 and the comparative developing devices 9 to 19 according to the present invention is mounted is manufactured, and an image output test is performed as follows. The image forming conditions were performed.

  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)
The number of rotations of the developer carrying member (developing sleeve) is adjusted within the range of 210 to 280 rpm, and the toner adhesion amount (M) per unit area on the photosensitive drum is 0.4 mg / cm ^2. did.

-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 when viewed from the developer conveying direction by the first stirring member, and the toner replenishment motor is driven according to the detection result. Controlled.

-Toner replenishment speed: Max. 30 g / min
Photoconductor surface potential: Maximum exposed portion potential (VL): -50V to -100V
The charging potential (VH) was controlled to be 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) Continuous output of 50 single blue characters / line patterns (printing rate of 7% for both M and C).
<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 it is slightly crushed (slightly filled with toner scatter) but the toner scatter around the character is small, the space of the letters “△” and “bell” is crushed (filled with toner scatter). Moreover, the case where there is a lot of toner geography 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 contamination is observed, or when only a slight contamination is seen only in the developing device mounting portion, “○” is indicated, and slight contamination 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 Table 2 correspond to the developing device numbers in Table 1.

<Experimental example 2>
[Production of development device]
In each of the developing devices 1 to 5 and 10 to 19 used in Experimental Example 1, a developing device (1 to 5, 10 to 19: corresponding to a developing toner supply port formed at a position 8 mm upstream from the toner supply port. For the sake of clarity, the same number is displayed).

  In accordance with the configuration shown in FIG. 12, an image forming apparatus for forming a monochrome image having toner recycling means mounted thereon with each of the developing devices 1 to 5 and 10 to 19 was 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.

For each of the image forming apparatuses equipped with the developing device, the process speed is set to 320 mm / sec (the number of image forming sheets per minute is 65 sheets), and the first stirring member, the second stirring member, and the third stirring speed are set. The rotational speed of each of the stirring member and the developer supply / recovery member is set according to the conditions shown in Table 3 below, and under the same image forming conditions as the image forming unit related to the color toner image of Experimental Example 1, The image output of (9) is repeated 8 times (a total of A4 × 2000). According to the image output test, the presence / absence of fogging of characters / line patterns, the presence / absence of character scattering, and the presence / absence of in-machine contamination The evaluation was performed based on the evaluation criteria described above, and the presence / absence of occurrence of image density unevenness of the solid pattern 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 (BK) solid pattern page, the relative reflection density at all locations is 1.3 or more, and the maximum and minimum values. Is less than or equal to 0.1, the minimum value of the relative reflection density 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. In some cases, “Δ” is indicated, and in the case where 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, “X” is indicated.

  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) provided with toner recycling means, the rotation speed of the rotating member is increased to obtain a sufficient developer moving speed, thereby suppressing the occurrence of image density unevenness 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 the schematic which shows the structure of the image development apparatus for a comparison.

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 member 810 Housing 812 Cover 813 Toner supply port 850 Spiral rib 855, 856, 858 Plate-shaped rib

Claims (8)

A developer carrying body for carrying and conveying a developer including toner and a carrier; and a side close to the developer carrying body and facing the longitudinal direction of the developer carrying body, and the developer is placed in a predetermined direction. A first agitating member that is agitated while being conveyed, and a side that is far from the developer carrying member and is opposed to the longitudinal direction of 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 is provided between the developer carrier and the first stirring member, and supplies the developer to the developer carrier; A developer supply / recovery member that recovers the developer removed from the developer carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatable. A housing for supporting the shaft, and the housing In the developing apparatus having a cover which is provided on the part,
The first agitating member and the second agitating member are extended to a side corresponding to the downstream side in the developer conveying direction by the first agitating member and protrude from the end of the developer carrier. With
The second agitating member is provided on the downstream side in the developer conveying direction by the first agitating member, and has a stirring portion 2A having a developer conveying ability lower than that of the first agitating member, and the first agitating member. A stirring portion 2B provided on the upstream side in the developer transport direction and having substantially the same developer transport capability as the first stirring member;
A third agitating member having a developer conveying capability substantially the same as or lower than that of the agitating part 2A and agitating while conveying the developer in the same direction as the developer conveying direction by the agitating part 2A; While arrange | positioning facing 2 A of stirring parts of a 2nd stirring member,
When the stirring portion 2A of the second stirring member and the third stirring member are viewed at their opposing proximity points, the rotation direction is determined such that the peripheral surface moves in the forward direction from the top to the bottom, and
A region between the shafts of the region where the stirring portion 2A of the second stirring member and the third stirring member are opposed to each other, the region corresponding to the upstream side in the developer transport direction by the third stirring member. A toner supply port for supplying toner is provided on the cover.
A developing device. A developer carrying body for carrying and conveying a developer including toner and a carrier; and a side close to the developer carrying body and facing the longitudinal direction of the developer carrying body, and the developer is placed in a predetermined direction. A first agitating member that is agitated while being conveyed, and a side that is far from the developer carrying member and is opposed to the longitudinal direction of 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 is provided between the developer carrier and the first stirring member, and supplies the developer to the developer carrier; A developer supply / recovery member that recovers the developer removed from the developer carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatable. A housing for supporting the shaft, and the housing In the developing apparatus having a cover which is provided on the part,
The first agitating member and the second agitating member are extended to a side corresponding to the downstream side in the developer conveying direction by the first agitating member and protrude from the end of the developer carrier. With
The first stirring member is constituted by a spiral rib provided around the rotation axis, and
The second agitating member is provided on the downstream side in the developer conveying direction by the first agitating member, and has a spiral rib provided around the rotation axis and a plate-like rib extending in the rotation axis direction. A part 2A and a stirring part 2B provided on the upstream side in the developer conveying direction by the first stirring member and having a spiral rib provided around the rotation axis; and
A third agitating member having a developer conveying capability substantially the same as or lower than that of the agitating part 2A and agitating while conveying the developer in the same direction as the developer conveying direction by the agitating part 2A; While arrange | positioning facing 2 A of stirring parts of a 2nd stirring member,
When the stirring portion 2A of the second stirring member and the third stirring member are viewed at their opposing proximity points, the rotation direction is determined such that the peripheral surface moves in the forward direction from the top to the bottom, and
The region between both shafts of the region where the stirring portion 2A of the second stirring member and the third stirring member are opposed to each other, in the region corresponding to the upstream side in the developer transport direction by the third stirring member. A toner supply port for supplying toner is provided on the cover.
A developing device. A developer carrying body for carrying and conveying a developer including toner and a carrier; and a side close to the developer carrying body and facing the longitudinal direction of the developer carrying body, and the developer is placed in a predetermined direction. A first agitating member that is agitated while being conveyed, and a side that is far from the developer carrying member and is opposed to the longitudinal direction of 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 is provided between the developer carrier and the first stirring member, and supplies the developer to the developer carrier; A developer supply / recovery member that recovers the developer removed from the developer carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatable. A housing for supporting the shaft, and the housing In the developing apparatus having a cover which is provided on the part,
The first agitating member and the second agitating member are extended to a side corresponding to the downstream side in the developer conveying direction by the first agitating member and protrude from the end of the developer carrier. With
The first stirring member is constituted by a spiral rib provided around the rotation axis, and
The second agitating member is provided on the downstream side in the developer conveying direction by the first agitating member, and has a stirring portion 2A having a developer conveying ability lower than that of the first agitating member, and the first agitating member. A stirring portion 2B provided on the upstream side in the developer transport direction and having substantially the same developer transport capability as the first stirring member;
Stirring while transporting the developer in the same direction as the developer transport direction by the stirring portion 2A, comprising a semi-elliptical plate-like member arranged in an inclined manner in the first direction and the second direction with respect to the rotation axis. A third agitating member is disposed opposite the agitating portion 2A of the second agitating member, and
When the stirring part 2A of the second stirring member and the third stirring member are viewed at their opposing proximity points, the rotation direction is determined such that the peripheral surface moves in the forward direction from the top to the bottom,
A region between the shafts of the region where the stirring portion 2A of the second stirring member and the third stirring member are opposed to each other, the region corresponding to the upstream side in the developer transport direction by the third stirring member. A toner supply port for supplying toner is provided on the cover.
A developing device. 4. The development according to claim 1, wherein the developer carrying member and the developer supply / recovery member have circumferential surfaces that move in directions opposite to each other when viewed from their proximity points. 5. apparatus. 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 containing the toner and 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 Claim 1 thru | or 5 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 first stirring member is W [g / sec], and the rotation speed of the first stirring member is R [rpm]. 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 5 is used as the developing unit, and the region on the cover of the developing device is opposed to the stirring portion 2A and the third stirring member. An image forming apparatus, wherein a recycled toner supply port for supplying recycled toner is provided at a position corresponding to an inter-shaft portion of both. 8. The image forming apparatus according to claim 7, wherein the recycled toner supply port is located upstream of the toner supply port as viewed in the developer conveying direction of the third stirring member.

Images