JP2005164999A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device and image forming apparatus of a configuration capable of imparting a prescribed amount of electrostatic charges to toner and forming a high quality image without reducing the transport speed of developer in spite of a simple configuration. <P>SOLUTION: The developing device has: a configuration to cyclically transport the developer with a first stirring member, a second stirring member, and a third stirring member disposed to face part of the first stirring member; and a configuration to sink the toner replenished into the opposite portions of the first stirring member and the third stirring member through a toner supply port disposed above the cover of a housing into the developer by means of the rotation of the first and third stirring members of which the respective circumferential surfaces are so rotated as to move from above to below. The image forming apparatus is equipped with the aforesaid 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 problems.

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

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

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

  In other words, when the circulating conveyance speed of the developer decreases, the toner concentration of the developer supplied to the developer carrier becomes nonuniform in the direction of the rotation axis of the developer carrier, and in particular, images with a high printing rate are continuously displayed. When output in this manner, image density unevenness is likely to occur, and it becomes difficult to form a high-quality image.

  In this way, if the developer agitation ability is increased to prevent the occurrence of fog and toner scattering so that the replenished new toner can obtain a sufficient charge amount in a short time, the developer conveyance ability decreases. 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 containing toner and a carrier, a side close to the developer carrying member, and provided along the longitudinal direction of the developer carrying member; A first stirring member that stirs while being conveyed in a predetermined direction; and a developer that is provided on the side far from the developer carrying member and along the longitudinal direction of the first stirring member, and is formed by the first stirring member A second agitating member that agitates the developer while conveying the developer in a direction opposite to the conveying direction, and is provided between the developer carrying member and the first agitating member, and supplies the developer to the developer carrying member. A developer supply / recovery member that recovers the developer removed from the developer carrier, and the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatable. A housing that is pivotally supported on the housing, and the housing And a cover provided on the top, in the developing device in which circulating conveying the developer accommodated in the accommodation stirring portion by said second agitating member and said first stirring member,
The first agitating member and the second agitating member are extended to the side corresponding to the downstream side in the developer conveying direction by the first agitating member, and the developer carrier and the developer supply and recovery member With a configuration that protrudes from the end,
The first agitating member is provided in the protruding region and has a developer conveying ability lower than that of the second agitating member, and is developed in a direction opposite to the developer conveying direction by the second agitating member. The stirring portion 1B that transports the developer and the stirring portion 1B that has substantially the same developer transport capability as the second stirring member and transports the developer in the direction opposite to the developer transport direction by the second stirring member. And,
Third developer that has substantially the same or lower developer conveying ability than the stirring portion 1A of the first agitating member, and agitates while conveying the developer in the same direction as the conveying direction of the first agitating member. While disposing the stirring member facing the stirring portion 1A of the first stirring member,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
A toner supply port for supplying toner is provided on the cover in a region corresponding to the upstream side when the stirring portion 1A and the third stirring member are opposed to each other and viewed in the developer transport direction by the third stirring member. Provided,
A developing device.

(2) a developer carrying body for carrying and conveying a developer including toner and a carrier, a side close to the developer carrying body, and provided along the longitudinal direction of the developer carrying body; A first stirring member that stirs while being conveyed in a predetermined direction; and a developer that is provided on the side far from the developer carrying member and along the longitudinal direction of the first stirring member, and is formed by the first stirring member A second agitating member that agitates the developer while conveying the developer in a direction opposite to the conveying direction, and is provided between the developer carrying member and the first agitating member, and supplies the developer to the developer carrying member. A developer supply / recovery member that recovers the developer removed from the developer carrier, and the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatable. A housing that is pivotally supported on the housing, and the housing And a cover provided on the top, in the developing device in which circulating conveying the developer accommodated in the accommodation stirring portion by said second agitating member and said first stirring member,
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 the end of the developer carrier and the developer supply / recovery member With a structure that protrudes from the part,
The second stirring member is constituted by a spiral rib, and
The first stirring member is provided in the protruding region and has a spiral rib and a plate-like rib provided in the rotation axis direction, and has a lower developer conveying ability than the second stirring member. Thus, the stirring portion 1A for transporting the developer in the direction opposite to the transport direction by the second stirring member, the spiral rib, and the developer transporting capability substantially the same as the second stirring member and the second stirring member 1A. 2 comprises a stirring portion 1B for transporting the developer in the direction opposite to the transport direction by the stirring member, and
A third agitating member having a developer conveying ability substantially the same as or lower than the agitating portion 1A of the first agitating member and conveying the developer in the same direction as the conveying direction by the first agitating member; While being disposed opposite to the stirring portion 1A,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device.

(3) a developer carrying body for carrying and conveying a developer including toner and a carrier, a side close to the developer carrying body, and provided along the longitudinal direction of the developer carrying body. A first stirring member that stirs while being conveyed in a predetermined direction; and a developer that is provided on the side far from the developer carrying member and along the longitudinal direction of the first stirring member, and is formed by the first stirring member A second agitating member that agitates the developer while conveying the developer in a direction opposite to the conveying direction, and is provided between the developer carrying member and the first agitating member, and supplies the developer to the developer carrying member. A developer supply / recovery member that recovers the developer removed from the developer carrier, and the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatable. A housing that is pivotally supported on the housing, and the housing And a cover provided on the top, in the developing device in which circulating conveying the developer accommodated in the accommodation stirring portion by said second agitating member and said first stirring member,
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 the end of the developer carrier and the developer supply / recovery member With a structure that protrudes from 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 stirring member is constituted by a spiral rib, and
The first agitating member is provided in the protruding region and has a developer conveying ability lower than that of the second agitating member, and a developer in a direction opposite to the developer conveying direction by the second agitating member. And a stirring portion 1B that has substantially the same developer transport capability as the second stirring member and that transports the developer in a direction opposite to the developer transport direction by the second stirring member. In addition,
A plurality of plate-like members provided inclined with respect to the rotation axis in the first direction, and a plurality of plate-like members provided inclined with respect to the second direction; and the stirring of the first stirring member A third agitating member that has substantially the same or lower developer conveying capacity as that of the part 1A and that conveys the developer in the same direction as the conveying direction by the first agitating member is disposed opposite the agitating part 1A. And also
The stirring portion 1A and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device.

  (4) Any one of the above (1) to (3), wherein the developer carrying member and the developer supply / recovery member have their peripheral surfaces rotating in opposite directions 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 second stirring member is W [g / sec], and the rotation speed of the second stirring member is R [rpm]. When W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus.

(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 means, and the developing device is on the cover of the developing device and corresponds between the stirring portion 1A and the third stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner at a position where the toner is supplied.

  (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-described configuration, the developer is circulated and conveyed in the direction of the rotation axis of the developer carrier while stirring the developer mainly in the circumferential direction by the first agitating member and the second agitating member, and the developer conveying speed, Alternatively, a sufficient amount of stirring time can be secured without balancing the transport amount and without reducing the transport speed of the developer.

  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.

  Moreover, while facing a part of longitudinal direction of a 1st stirring member, the 3rd stirring member is provided in the position on the opposite side to the said 2nd stirring member, and the 1st, 3rd stirring member is both opposing proximity | contact In view of the point, each peripheral surface is configured to move in the forward direction from the upper side to the lower side (synonymous with rotating in the same direction when viewed from the opposite proximity point), and the upper side corresponding to the opposite part of both Therefore, 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 with a large amount of toner consumption and toner replenishment is used by continuously outputting images with a high printing rate, or when the charging performance is inferior to that of unused toner. 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 (synonymous with electrostatic charge latent image forming means), a transfer means 340, and a blade (cleaning means) for cleaning the surface of the photosensitive drum 310 after transfer. The cleaning device 350 including the developing device 8 and the developing device 8 that visualizes the electrostatic latent image are main components.

  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 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 drum cleaning unit 350, and preparations for new image formation are made.

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

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

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

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

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

  It is desirable that an appropriate transfer bias voltage is applied to the transfer roller 510 during transfer.

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

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

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

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

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

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

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

  Further, the behavior of the paper P in the double-sided copy mode using the ADU 7 is similar to that in the case of the reverse discharge. The paper P after the fixing process with the image formed on one side is moved along the right side of the switching member 601. Then, after stopping the conveyance with the 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, a first stirring member 803 provided along the longitudinal direction of the developer carrying member 800 (meaning to be opposed), and the developer carrying member 800. On the other hand, the second stirring member 805 provided along the longitudinal direction of the first stirring member at a position farther (rear side) than the first stirring member 803, the developer carrier 800, and the first A developer supply / recovery member 809 provided between the stirring member 803, a third stirring member 807 provided to face a partial region in the longitudinal direction of the first stirring member, and these members in the axial direction. A housing 810 that rotatably supports the shaft while maintaining a parallel state, and an openable / closable cover 812 that covers the upper portion of the housing. The third stirring member 807 is provided on the side opposite to the side on which the second stirring member 805 is provided with the first stirring member 803 (side where the developer supply and recovery member is provided).

  Specifically, while the developer carrier 800 and the developer supply / recovery member 809 are substantially the same length, the first stirring member 803 and the second stirring member 805 are set longer than that. It is.

  Then, by positioning one end position of both agitating members in substantially the same plane as the end position of the developer supply / recovery member or the like, the other end protrudes toward one end of the developer supply / recovery member. The third stirring member 807 is provided in a region formed by one end of the developer supply and recovery member and the protruding portion of the stirring member.

  In other words, as shown in FIG. 2, the third agitating member 807 extends and projects toward the downstream side in the developer conveyance direction by the first agitating member 803, and the third agitating member 807 is accommodated in the projecting region 802. The first stirring member 803 (corresponding to a stirring portion 1A described later) is provided.

  Reference numerals 820 and 821 denote developer paths which are circulated and conveyed.

  Further, reference numeral 815 in FIG. 3 is a space formed in the housing 810, that is, a developer supply / recovery unit, and 816 is a developer storing and agitating unit. An appropriate amount of a two-component developer containing magnetic toner is stored.

  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 in the developer carrier 800. All the rotating members included are configured to receive power from a drive system provided on the image forming apparatus main body side and rotate in the direction of the arrow via a gear or the like, and a known technique can be used for the power transmission mechanism.

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

  As is clear from this, the first stirring member 803 and the third stirring member 807 are axially rotated so that the circumferential surface of the stirring member moves in the forward direction from the upper side to the lower side when viewed from the opposing proximity point of both. This rotation direction serves to efficiently disperse the replenishment toner described later in the developer.

  Further, the developer carrier 800 and the developer supply / recovery member 809 are rotated in the opposite directions when viewed at the portion where they face each other (the proximity point between them).

  In this configuration, the developer supplied to the developer carrier 800 from the developer supply / recovery member 809 is removed from the developer carrier 800 after passing through the development region, and is collected by the developer supply / recovery member 809. Replacement with the developer can be performed reliably, and as a result, the toner density of the developer on the developer carrying member can be maintained in a uniform state, and thus has a function of suppressing occurrence of image density unevenness.

  As shown in FIG. 5, for example, the rotating member including the developer supply / recovery member is a spiral rib (with a predetermined pitch p in the axial direction over the entire outer peripheral surface of the shaft. Screw).

  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.

  A thick arrow in FIG. 2 indicates a developer transport direction when the first stirring member 803, the second stirring member 805, and the third stirring member 807 are rotated in the above-described direction. The length of the arrow indicates the developer length. The conveyance capability (developer conveyance speed, developer conveyance amount, etc.) is shown.

  As understood from the figure, when the first stirring member 803 and the second stirring member 805 rotate, the developer in the storage stirring portion 816 is circulated and conveyed in the direction of the arrow while being stirred in the circumferential direction of the stirring member. .

  The downstream ends of the first and second agitating members in the developer transport direction are formed into paddles by forming plate-like blade members (not shown) on the peripheral surface of the rotating shaft, and both the blade members are used by the blade members. The developer is circulated and conveyed smoothly through the stirring member.

  The developer containing toner that has reached a predetermined charge amount by the mixing / stirring action during the circulation and conveyance is sequentially developed via the developer supply / recovery member 809 while being conveyed by the first agitation member 803. It is supplied to the agent carrier 800 and is spent for development.

  On the other hand, the developer on the developer carrier 800 is automatically removed from the developer carrier by, for example, the action of a repulsive magnetic field after passing through the development region, and is first agitated by the developer supply / recovery member 809. It is collected on the member 803 side.

  Next, the developer transport capability will be described. In the present embodiment, when the developer transport capability of the second stirring member 805 is used as a reference, the first stirring member 803 is provided on the downstream side in the developer transport direction by the first stirring member. A portion having a developer conveying capability lower than the developer conveying capability of the second agitating member 805 (hereinafter, this portion is referred to as a stirring portion 1A), and provided integrally on the upstream side of the stirring portion 1A, The second agitating member 805 is composed of a portion having substantially the same developer conveying capability (hereinafter, this portion is referred to as a stirring portion 1B).

  Further, the third stirring member 807 is configured to have a developer transport capability that is substantially the same as or lower than the stirring portion 1A of the first stirring member.

  With such a configuration, the developer sent by the stirring portion 1B of the first stirring member 803 is transported in a shared manner by the stirring portion 1A and the third stirring member 807, and the mixing is performed here. The developer can be delivered to the second stirring member 805 without stirring and reducing the developer conveying speed.

  For example, this can be dealt with by setting the developer conveying ability of the stirring portion 1A and the third stirring member 807 to be about ½ of the developer conveying ability of the second stirring member 805, respectively.

  The developer conveying ability can be appropriately selected and determined within a range where there is no problem such as clogging of the developer and insufficient charge amount with respect to the toner.

  Note that the first agitating member is located upstream of the developer conveying direction in the longitudinal direction region where the agitating portion 1A and the third agitating member 807 are opposed to each other, as shown in a side cross section in FIG. A toner supply port 813 for supplying unused toner (hereinafter referred to as new toner) from a toner replenishing mechanism (not shown) is provided on the cover 812 corresponding to an intermediate portion between the 803 and the third stirring member 807. is there.

  The toner replenishing mechanism is provided above the toner supply port 813, for example.

  The position of the toner supply port 813 at the upstream position as described above is intended to be effective even when the length of the stirring portion 1A and the third stirring member 807 is short.

  Therefore, when the third stirring member 807 and the like have a sufficient length, it is sufficient that the third stirring member 807 and the like are not so much upstream. However, even in that case, due to uniform dispersion of new toner in the developer and friction of the developer. Considering the provision of the charge amount to the toner, the upstream side is preferable.

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

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

  Further, since sufficient stirring can be performed in the circumferential direction of the stirring member, for example, a developer having a uniform toner concentration in the axial direction of the second stirring member can be easily obtained in a short time, A predetermined charge amount can be imparted to the developer during the cyclic conveyance including the portion.

  Next, a specific configuration of the stirring member will be described with reference to FIG.

  The figure is a schematic view showing a first example of a stirring member, and is formed from a spiral rib 850 formed over the entire outer peripheral surface of a shaft (hereinafter also referred to as a rotating shaft) J with a predetermined pitch p in the axial direction. Become.

  The stirring member having the above-described configuration can basically be used for any of the first to third stirring members. However, when the developer transport capability is to be lowered, a pitch smaller than that when the pitch p is used as a reference. By setting p1, the developer conveying ability in the rotation axis direction can be lowered.

  For example, in the first embodiment relating to the developing device, the second stirring member 805 is configured by a spiral rib having a pitch p as a reference, and the stirring portion 1A of the first stirring member 803 is smaller than the pitch p. The pitch p1 and the stirring portion 1B can be configured by a spiral rib of the pitch p, and the third stirring member can be configured as the pitch p1.

  The toner used in the developing device according to the present invention preferably has a volume average particle diameter of 3 to 5 μm. Such a small particle diameter toner has high resolution and excellent fine line reproducibility. A toner image having a stable image density can be formed 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 amount of developer movement in the rotation axis direction of the developer carrier by the second stirring member W [G / sec], R represents the rotation speed [rpm] of the second stirring member, respectively.

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

Further, when the rotation speed of the second stirring member is excessive, the developer is likely to be deteriorated by heat generated at the shaft portion of the first stirring member, and it is difficult to form a high-quality image. Become.

  Note that the amount of movement or the number of rotations of the developer by the second agitating member can also be applied to the first agitating member (substantially the region of the agitating portion 1B) that can move substantially the same amount of developer. is there.

  Here, the behavior of the developer in the development process using the above-described developing device will be briefly described.

  When the second agitating member 805 starts rotating together with the developer carrying member 800, the first agitating member 803, the third agitating member 807, and the developer supply / recovery member 809 along with the development processing, the agitation unit 816 accommodates them. The developer is circulated and conveyed along the direction of the rotation axis J while being agitated in the circumferential direction of the second agitating member, and through the friction between the toner and the carrier in the process, or the friction with the housing or the like, The toner is given a predetermined charge amount.

  Next, at the end of the second agitating member 805, it is transferred to the first agitating member 803 and circulated and conveyed in the direction opposite to the conveying direction while receiving the agitation action.

  In this transport process, the developer is supplied to the developer carrier 800 via the developer supply / recovery member 809 accommodated in the developer supply / recovery unit 815, and is held in a magnetically attracted state throughout the entire surface in the axial direction. After being regulated by the layer thickness regulating blade Z, the latent image brought to the development area and formed on the image carrier is converted into a toner image.

  The developer that has passed through the development processing area is removed from the developer carrier 800 and is collected by the developer supply / recovery member 809 without being supplied to the developer carrier, and the first stirring member 803. It is sent toward.

  Thereafter, after being transported in the axial direction by the action of the first stirring member 803, the second stirring member 805 is again subjected to the stirring / conveying action, and such behavior is repeated.

  The toner density of the developer after the development processing is detected by the toner density detection sensor, and new toner is supplied from the toner supply mechanism through the toner supply port 813 based on the detected value.

  The supplied new toner freely falls between the stirring portion 1A and the third stirring member 807 of the first stirring member 803, and the developer existing around the shaft is rotated by the axial rotation of the stirring portion 1A and the third stirring member 807. It is immediately submerged and stirred, uniformly dispersed in the developer in a short time, and triboelectrically charged.

  Then, after the above-mentioned process of being conveyed while being stirred in the axial direction of the second stirring member 805, it is eventually used as a new development processing agent.

  Further, in such a process, the developer conveying capability of the first stirring member 803 and the third stirring member 807 and the total developer conveying capability of the second stirring member 805 are substantially equal, so that the developer conveying speed is The toner can be balanced, and a predetermined charge amount can be imparted to the toner through a sufficient mixing and stirring operation without lowering the developer conveyance speed.

  In addition, since the development process is performed in a state where the specific conditions (a) and (b) described above are satisfied, the developer can be supplied to the development region in the axial direction without toner density unevenness. An image having a uniform image density without image density unevenness can be obtained.

  In addition, by setting the rotation speed of the second stirring member to 600 rpm or less, it is possible to prevent the developer from being deteriorated by heat generated when the second 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.

  The first embodiment according to the present invention has been described above. In particular, the configuration of the stirring member is not limited to the specific configuration described above. For example, other configurations shown in FIGS. These stirring members can be used in appropriate combinations.

  In the figure, the same reference numerals are assigned to the same members as those already described.

  The configuration of 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 members provided inclined in the second direction. It has a plate-like member.

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

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

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

  The stirring member shown in FIG. 7 is formed 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 with the spiral rib 850 formed at a pitch p having a predetermined size in the axial direction. And rod-like or plate-like ribs (vertical blades) 855 provided so as to extend outward in the radial direction.

  The ribs 855 are provided between the pitches p of the spiral ribs 850, and are provided in a line (straight) 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 formed 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 with a spiral rib 850 formed at a pitch p having a predetermined size in the axial direction. Rod-shaped or plate-like ribs (vertical blades) 856 provided in a row in the direction of the rotation axis, and the rows of ribs 856 are 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 an outer peripheral edge portion of the spiral rib. A row of notches 857 extending in the axial direction is formed. For example, when the figure is viewed from the side, the notches 857 have a four-row arrangement in which the phases are shifted by 90 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, the sixth example and the seventh example of the stirring member having higher developer stirring ability than the stirring member described so far will be described with reference to FIGS.

  The stirring member shown in FIG. 10 extends over the entire outer peripheral surface of the rotary shaft J and has a spiral rib 850 formed at a predetermined pitch p in the axial direction, and the outer peripheral edge of the spiral rib. And a plate-like rib 858 extending linearly in the direction of the rotation axis J. Further, in this example, the ribs are provided at two locations (upper edge portion and lower edge portion in the drawing) which are axial objects.

  The agitating member shown in FIG. 11 has the same basic configuration as that of FIG. Plate members 851 and 852 made of an elliptical plate are provided to be inclined, and a plurality of such sets are arranged in the axial direction at a predetermined pitch p, and at the outer peripheral edge of the plate members 851 and 852, A plate-like rib 858 extending linearly in the direction of the rotation axis J is provided.

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

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

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

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

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

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

  If the developer supply / recovery member 809 and the third stirring member 807 are to be shown in the drawing, the positions overlap, and therefore, the two arrows indicating the rotation direction are indicated by reference numerals indicating both members. did.

  That is, the solid arrow indicates that the circle including the arrow is the developer supply / recovery member 809 and is rotated in the counterclockwise direction, and the broken arrow indicates a circle including the arrow. Indicates that the third stirring member 807 rotates clockwise.

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

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

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

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

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

  The 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.

  The recycled toner supply port 825 is a substantially intermediate position where the agitating portion 1A of the first agitating member 805 and the third agitating member 807 face each other, as viewed in the developer conveying direction by the third agitating member. It is provided on the cover 812 corresponding to an appropriate position upstream of the toner supply port 813.

  The relative 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.

  The distance between the two is not particularly limited, but it is practically preferable to provide the recycled toner supply port 825 at an upstream position about 5 to 30 mm from the toner supply port in the developer transport direction.

  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 quickly sink into the developer recycled toner that has poor flowability and low chargeability compared to the new toner, and the mixing time can be reduced. Since the toner can be made longer, 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 image density unevenness in image formation can be suppressed. it can.

  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.

  Needless to say, the developing device of the second embodiment can also be applied to the image forming apparatuses shown as the first and second embodiments.

  Note that the charging process for the developer guided to the circulation conveyance path, the charging process for the developer including the new toner and the recycled toner, the uniform toner dispersion, the developer conveyance amount, etc. A detailed description is omitted here.

  Next, experimental examples conducted for confirming the effects of the present invention will be described.

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

  The specifications of the rotating member WW are as follows.

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

  The specifications of the rotating member XX are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, thickness of plate member: 1 mm, shaft of plate member constituting first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring section: −45 °, pitch of plate-like member (p): 25 mm, plate-like rib Radial length (t): 3 mm, plate-like rib thickness: 1 mm
(Rotating member QQ)
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 rotation axis direction excluding shaft portion: 360 mm, outer diameter of shaft member: 6 mm, thickness of plate-like rib member: 1 mm, radial length of plate-like rib: 9mm
(Rotating member D)
The rotating member AA has the same configuration as the rotating member AA except that the spiral rib is formed in a right-handed manner, the screw pitch of the spiral rib is 40 mm, and the axial length is 110 mm. A rotating member having.
(Rotating member 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) A rotating member having 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 in the rotating member EA.
(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 NA)
In the rotating member KA, the rotating member has the same configuration as the rotating member KA except that the spiral rib of the stirring portion A is wound clockwise and the pitch of the spiral rib of the portion is 20 mm.
(Rotating member WA)
As the stirring portion A (1A, 2A), a first member configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member shown in FIG. And a second stirring section, and integrally has a spiral rib (left-handed) shown in FIG. 5 as the stirring portion B (1B, 2B), and the entire developer. 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 WA are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 440 mm (however, the stirring part A is 110 mm, the stirring part B is 330 mm), and the plate-like member constituting the first stirring part is attached to the shaft Angle (α1): + 45 °, Mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring unit: -45 °, plate-like member thickness: 1 mm, plate-like member arrangement pitch: 25 mm, spiral Rib pitch: 30 mm, spiral rib thickness: 1 mm
(Rotating member XA)
As the stirring portion A (1A, 2A), as shown in FIG. 11, a plurality of semi-elliptical plate-like members are provided so as to be inclined in different directions with respect to a plane perpendicular to the shaft member. Four locations on the outer peripheral edge of the plate-like member constituting the first stirring section and the second stirring section, which have a first stirring section and a second stirring section, and are equidistant in the circumferential direction Is provided with a plate-like rib extending in the axial direction without a break, and integrally has a spiral rib (left-handed) shown in FIG. 5 as the stirring portion B (1B, 2B). And, on the outer peripheral surface of the shaft member extending 30 mm in length downstream in the overall developer conveyance direction, four flat blade members are provided so as to extend outward in the radial direction to form a paddle shape, Disc-shaped francs with an outer dimension of 24 mm at both ends of the rotating member Configuration and the rotating member provided with members.

  The specifications of this rotating member are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis excluding shaft portion: 440 mm (however, stirring portion A is 110 mm, stirring portion B is 330 mm), relative to the axis of the plate-like member constituting the first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate member constituting the second stirring section: −45 °, plate member thickness: 1 mm, plate member arrangement pitch: 25 mm, The radial length (t) of the plate-like rib: 3 mm, the axial length of the plate-like rib: 110 mm, the thickness of the plate-like rib: 1 mm, the pitch of the helical rib: 30 mm, the length of the helical rib Thickness: 1mm
(Rotating member 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 OE)
In the rotating member YE, the spiral rib with a plate-like rib constituting the stirring portion A is wound clockwise, the screw pitch is 30 mm, and the radial length of the plate-like rib is 5 mm. Others are rotating members having the same configuration as the rotating member YE.
(Rotating member PE)
In the rotating member YE, the spiral ribs with plate-like ribs constituting the stirring portion A are wound clockwise, the screw pitch is 30 mm, and the plate-like ribs are attached at four locations with equal distribution in the circumferential direction. A rotating member having the same configuration as that of the rotating member YE except for the above.
(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.
(Rotating member WG)
As the stirring portion A (1A, 2A), a first member configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member shown in FIG. A stirring portion and a second stirring portion, and the stirring portion B (1B, 2B) has a spiral rib (left-handed) including the plate-like rib shown in FIG. 7, and Four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the overall conveyance direction of the developer so as to extend outward in the radial direction to form a paddle, and this rotating member A rotating member having a configuration in which a disc-shaped flange member having an outer dimension of 24 mm is provided at both end portions.

  The specifications of the rotating member WG are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 440 mm (however, the stirring portion A is 110 mm, the stirring portion B is 330 mm), and the plate member constituting the first stirring portion is attached to the shaft. Angle (α1): + 45 °, Mounting angle (α2) with respect to the axis of the plate-like member constituting the second stirring unit: -45 °, plate-like member thickness: 1 mm, plate-like member arrangement pitch: 25 mm, spiral Pitch of ribs (p): 30 mm, Thickness of spiral ribs: 1 mm, Radial length (h) of plate ribs (vertical blades): 8 mm, Axial length of plate ribs (W ): 3 mm, plate-like rib arrangement: one per pitch (center position between screw pitches), plate-like rib thickness: 1 mm
(Rotating member XG)
As the stirring portion A (1A, 2A), as shown in FIG. 11, a plurality of semi-elliptical plate-like members are provided so as to be inclined in different directions with respect to a plane perpendicular to the shaft member. Four locations on the outer peripheral edge of the plate-like member constituting the first stirring section and the second stirring section, which have a first stirring section and a second stirring section, and are equidistant in the circumferential direction A plate-like rib extending in the axial direction is provided at the position, and a spiral rib (left-handed) including the plate-like rib shown in FIG. 7 is used 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 conveyance direction of the developer so as to extend radially outward. A circle with an outer dimension of 24 mm at both ends of the rotating member. Configuration and the rotating member provided with Jo flange member.

  The specifications of this rotating member 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), relative to the axis of the plate-like member constituting the first stirring portion Mounting angle (α1): + 45 °, mounting angle (α2) with respect to the axis of the plate member constituting the second stirring section: −45 °, plate member thickness: 1 mm, plate member arrangement pitch: 25 mm, Spiral rib pitch (p): 30 mm, spiral rib thickness: 1 mm, radial length (h) of plate-like rib (vertical blade): 8 mm, axial length of plate-like rib ( W): 3 mm, plate-like rib arrangement: one per pitch (center position between screw pitches), plate-like rib thickness: 1 mm
<Experimental example 1>
[Create developer]
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 first 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.

  Furthermore, as shown in FIG. 14, the stirring portion 1A of the first stirring member is eliminated, and the developer transport capability is configured to be substantially the same as the transport capability of the second stirring member, 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 position where the toner supply port is formed in each of the developing devices 1 to 9 is a portion where the stirring portion 1A of the first stirring member and the third stirring member face each other (when viewed in a cross section perpendicular to the longitudinal direction, the middle of both members). ) And a position 15 mm downstream from the upstream edge in the developer transport direction by both stirring members.

  On the other hand, the toner supply port forming position in each of the developing devices 10 to 19 is an upper position on the front side of the first stirring member, and is an upstream end of the protruding region 802 in the developer transport direction by the first stirring member. It is a position 15 mm downstream from the edge.

  As the developer, a two-component developer having a toner concentration of 7% by mass is used for each of the developers related to yellow toner, magenta toner, cyan toner, and black toner, and 1100 g is used for developing devices 1 to 9. The 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 19 is mounted on an appropriate driving machine, and the developer movement is performed by setting the rotation amounts of the first stirring member, the second stirring member, and the third stirring unit member as shown in Table 1 below. The amount was measured.

  The results are shown in Table 1 above.

  Note that the developer movement amount is measured by driving the other rotating member in a state where the developer carrying member and the developer supply / recovery member are stopped, and downstream of the second stirring member in the developer transport direction. This was carried out by measuring the weight of the developer discharged per unit time from the developer discharge port provided in.

  In Table 1, “the moving direction in the first / third counter part” indicates the moving direction when viewed in the close-facing position between the first stirring member and the third stirring member.

  Further, in Table 1, two types of rotation speeds are shown for the rotation members corresponding to the developing devices 13 to 19. The rotation speed of 400 rpm is the rotation speed in color image formation, and 650 rpm is in the monochrome image formation. The rotation speeds are related to Tables 2 and 3 described later.

  For the other developing devices 1 to 12, the rotational speed of the rotating member in color image formation and monochrome image formation is 400 rpm.

[Image forming apparatus]
According to the configuration shown in FIG. 1, color image forming image forming apparatuses 1 to 19 mounted with developing devices 1 to 19 were manufactured, and an image output test was performed under the following image forming conditions.

The image forming conditions were set to be the same for all of the image forming units related to the respective color toner images.
<Image forming conditions>
-Process speed (V): 220 mm / sec (number of images formed per minute is 50)
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”.

<Experimental example 2>
[Production of development device]
Each of the developing devices 1 to 5 and the developing devices 10 to 19 used in Experimental Example 1 has the same configuration except that a recycled toner supply port is formed at a position 8 mm upstream of the toner supply port. 1-5 and 10-19 were prepared.

  In accordance with the configuration shown in FIG. 12, the image forming apparatuses 1 to 5 and 10 to 19 for forming a monochrome image having toner recycling means on which each of the developing devices 1 to 5 and 10 to 19 is mounted (for easy understanding) Therefore, the development device number is unified.

  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, the process speed is set to 320 mm / sec (the number of image forming sheets per minute is 65), and the first stirring member, the second stirring member, the third stirring member, and the development The rotation speed of each of the agent supply / recovery members was set to 400 rpm for the developing devices 1 to 5 and 10 to 12 and 650 rpm for the developing devices 13 to 19 except that the black (black: BK) Under the same image forming conditions as the image forming unit related to the toner image, the image output of the following (7) to (9) is repeated 8 times (a total of A4 × 2000 sheets). / Evaluates the presence or absence of fogging of line patterns, the presence or absence of character scattering, and the presence or absence of dirt in the machine based on the evaluation criteria described above, and The evaluation of the presence or absence of image density unevenness generated pattern was 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>
Image density unevenness is measured by measuring the relative reflection density at any nine locations in the page of the black solid pattern, the relative reflection density at all locations is 1.3 or more, and the difference between the maximum value and the minimum value is The case where it is 0.1 or less is “◯”, the case where 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. The case where “Δ”, 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 is “x”.

  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.

  In addition, the occurrence of image defects such as image fogging, character scattering, and image density unevenness can be suppressed, and the occurrence of in-machine contamination due to toner scattering can be reduced to form 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, which is provided along a longitudinal direction of the developer carrying body, and the developer is placed in a predetermined direction. A first stirring member that stirs while being transported, and a side far from the developer carrier, and is provided along the longitudinal direction of the first stirring member, and the developer transport direction by the first stirring member And a second agitating member for agitating while conveying the developer in the opposite direction, and provided between the developer carrying member and the first agitating member for supplying the developer to the developer carrying member and developing the developer A developer supply / recovery member that recovers the developer removed from the carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatably supported. Housing and the upper part of the housing And a cover provided in the developing device in which circulating conveying the developer accommodated in the accommodation stirring portion by said second agitating member and said first stirring member,
The first agitating member and the second agitating member are extended to the side corresponding to the downstream side in the developer conveying direction by the first agitating member, and the developer carrier and the developer supply and recovery member With a configuration that protrudes from the end,
The first agitating member is provided in the protruding region and has a developer conveying ability lower than that of the second agitating member, and is developed in a direction opposite to the developer conveying direction by the second agitating member. The stirring portion 1B that transports the developer and the stirring portion 1B that has substantially the same developer transport capability as the second stirring member and transports the developer in the direction opposite to the developer transport direction by the second stirring member. And,
Third developer that has substantially the same or lower developer conveying ability than the stirring portion 1A of the first agitating member, and agitates while conveying the developer in the same direction as the conveying direction of the first agitating member. While disposing the stirring member facing the stirring portion 1A of the first stirring member,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
A toner supply port for supplying toner is provided on the cover in a region corresponding to the upstream side when the stirring portion 1A and the third stirring member are opposed to each other and viewed in the developer transport direction by the third stirring member. Provided,
A developing device. A developer carrying body for carrying and conveying a developer including toner and a carrier, and a side close to the developer carrying body, which is provided along a longitudinal direction of the developer carrying body, and the developer is placed in a predetermined direction. A first stirring member that stirs while being transported, and a side far from the developer carrier, and is provided along the longitudinal direction of the first stirring member, and the developer transport direction by the first stirring member And a second agitating member for agitating while conveying the developer in the opposite direction, and provided between the developer carrying member and the first agitating member for supplying the developer to the developer carrying member and developing the developer A developer supply / recovery member that recovers the developer removed from the carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatably supported. Housing and the upper part of the housing And a cover provided in the developing device in which circulating conveying the developer accommodated in the accommodation stirring portion by said second agitating member and said first stirring member,
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 the end of the developer carrier and the developer supply / recovery member With a structure that protrudes from the part,
The second stirring member is constituted by a spiral rib, and
The first stirring member is provided in the protruding region and has a spiral rib and a plate-like rib provided in the rotation axis direction, and has a lower developer conveying ability than the second stirring member. Thus, the stirring portion 1A for transporting the developer in the direction opposite to the transport direction by the second stirring member, the spiral rib, and the developer transporting capability substantially the same as the second stirring member and the second stirring member 1A. 2 comprises a stirring portion 1B for transporting the developer in the direction opposite to the transport direction by the stirring member, and
A third agitating member having a developer conveying ability substantially the same as or lower than the agitating portion 1A of the first agitating member and conveying the developer in the same direction as the conveying direction by the first agitating member; While being disposed opposite to the stirring portion 1A,
The stirrer 1A and the third stirrer are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device. A developer carrying body for carrying and conveying a developer including toner and a carrier, and a side close to the developer carrying body, which is provided along a longitudinal direction of the developer carrying body, and the developer is placed in a predetermined direction. A first stirring member that stirs while being transported, and a side far from the developer carrier, and is provided along the longitudinal direction of the first stirring member, and the developer transport direction by the first stirring member And a second agitating member for agitating while conveying the developer in the opposite direction, and provided between the developer carrying member and the first agitating member for supplying the developer to the developer carrying member and developing the developer A developer supply / recovery member that recovers the developer removed from the carrier, the developer carrier, the first stirring member, the second stirring member, and the developer supply / recovery member are rotatably supported. Housing and the upper part of the housing And a cover provided in the developing device in which circulating conveying the developer accommodated in the accommodation stirring portion by said second agitating member and said first stirring member,
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 the end of the developer carrier and the developer supply / recovery member With a structure that protrudes from 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 stirring member is constituted by a spiral rib, and
The first agitating member is provided in the protruding region and has a developer conveying ability lower than that of the second agitating member, and a developer in a direction opposite to the developer conveying direction by the second agitating member. And a stirring portion 1B that has substantially the same developer transport capability as the second stirring member and that transports the developer in a direction opposite to the developer transport direction by the second stirring member. In addition,
A plurality of plate-like members provided inclined with respect to the rotation axis in the first direction, and a plurality of plate-like members provided inclined with respect to the second direction; and the stirring of the first stirring member A third agitating member that has substantially the same or lower developer conveying capacity as that of the part 1A and that conveys the developer in the same direction as the conveying direction by the first agitating member is disposed opposite the agitating part 1A. And also
The stirring portion 1A and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable in the forward direction from the top to the bottom,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the developer stirring direction by the third stirring member, where the stirring portion 1A and the third stirring member are opposed to each other. With a mouth,
A developing device. 4. The development according to claim 1, wherein the developer carrying member and the developer supply / recovery member have circumferential surfaces that rotate 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 second stirring member is W [g / sec], and the rotation speed of the second stirring member is R [rpm]. When
W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus. An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier A transfer unit that transfers the image to a transfer material or an intermediate transfer member; a cleaning unit that cleans the surface of the image carrier after the transfer; and a toner that is removed from the surface of the image carrier by cleaning is supplied to the developing unit. In an image forming apparatus having toner recycling means for recycling,
The developing device according to any one of claims 1 to 5 is used as the developing unit, and the position is on the cover of the developing device and between the stirring portion 1A and the third stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner. 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.

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