JP3846465B2 - Developing device and image forming apparatus - Google Patents

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.

In order to deal with such problems, many techniques for improving the stirring efficiency of the developer have been proposed in the past.For example, by providing a member that functions as an auxiliary stirring member, the stirring means has a high developer stirring ability. For example, Patent Document 1, Patent Document 2, and Patent Document 3 are used.
Japanese Unexamined Patent Publication No. 07-013420 JP 09-166918 A JP 09-288212 A

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

  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 tends to occur, making it difficult to form a high-quality image.

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

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

  The object of the present invention can be achieved by the following constitution.

(1) A developer carrying member that carries and conveys a developer containing toner and a carrier, and a first stirring that is provided adjacent to the longitudinal direction of the developer carrying member and that stirs while carrying the developer in a predetermined direction. A member, a second stirring member provided adjacent to the longitudinal direction of the first stirring member, and stirring the developer while transporting the developer in a direction opposite to the developer transport direction by the first stirring member; and the developer A support body, a housing for rotatably supporting the first stirring member and the second stirring member, and a cover provided on the upper portion of the housing, and a partition wall between the stirring members In the developing device configured to circulate and convey the developer stored in the storage stirring portion by the first stirring member and the second 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 protrude from the end of the developer carrier. With
A third stirring member whose length in the rotation axis direction is shorter than that of the second stirring member and whose developer conveying ability in the rotation axis direction is substantially zero is set in the developer conveying direction by the second stirring member. Is provided opposite to the second stirring member on the upstream side,
The second stirring member and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable from above to below,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side when the second stirring member and the third stirring member are opposed to each other in the developer transport direction by the second stirring member. With a mouth,
A developing device.

(2) A developer carrying body for carrying and transporting a developer containing toner and a carrier, and a first stirring which is provided adjacent to the longitudinal direction of the developer carrying body and stirs while carrying the developer in a predetermined direction. A member, a second stirring member provided adjacent to the longitudinal direction of the first stirring member, and stirring the developer while transporting the developer in a direction opposite to the developer transport direction by the first stirring member; and the developer A support body, a housing for rotatably supporting the first stirring member and the second stirring member, and a cover provided on the upper portion of the housing, and a partition wall between the stirring members In the developing device configured to circulate and convey the developer stored in the storage stirring portion by the first stirring member and the second 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 protrude from the end of the developer carrier. Along with the spiral rib formed in the direction of the rotation axis,
Developing a third stirring member having a length in the rotation axis direction shorter than that of the second stirring member and comprising a plurality of plate-like members inclined in the same direction with respect to the rotation axis by the second stirring member. Provided facing the second stirring member on the upstream side in the agent transport direction,
The second stirring member and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable from above to below,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side when the second stirring member and the third stirring member are opposed to each other in the developer transport direction by the second stirring member. With a mouth,
A developing device.

(3) A developer carrying body for carrying and conveying a developer containing toner and a carrier, and a first agitation provided adjacent to the longitudinal direction of the developer carrying body and carrying the developer in a predetermined direction. A member, a second stirring member provided adjacent to the longitudinal direction of the first stirring member, and stirring the developer while transporting the developer in a direction opposite to the developer transport direction by the first stirring member; and the developer A support body, a housing for rotatably supporting the first stirring member and the second stirring member, and a cover provided on the upper portion of the housing, and a partition wall between the stirring members In the developing device configured to circulate and convey the developer stored in the storage stirring portion by the first stirring member and the second 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 protrude from the end of the developer carrier. Along with the spiral rib formed in the direction of the rotation axis,
A third stirring member including a plate-like rib having a length in the rotation axis direction shorter than the second stirring member and extending in the rotation axis direction with a gap between the rotation shaft and the rotation shaft; 2 provided opposite the second stirring member on the upstream side in the developer conveying direction by the stirring member,
The second stirring member and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable from above to below,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side when the second stirring member and the third stirring member are opposed to each other in the developer transport direction by the second stirring member. With a mouth,
A developing device.

  (4) The developer carrying member and the first agitating member move in opposite directions when viewed from their proximity points, as described in any one of (1) to (3) above Development device.

(5) The developer conveyed by the first stirring member is supplied to the developer carrying member between the developer carrying member and the first stirring member, and the first stirring member is supplied from the developer carrying member. A rotatable developer supply and recovery member for recovering the developer toward the
The developer supply / recovery member and the developer carrying member move in opposite directions as seen from their proximity points, as described in any one of (1) to (3) above Development device.

  (6) In the above (5), the peripheral surface of the first stirring member is moved from the lower side to the upper side when viewed from the proximity of the developer supply / recovery member and the first stirring member. The developing device described.

(7) 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 (6), wherein a developer containing the toner and carrier is used.

(8) 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 (7) is used,
The moving speed of the image carrier is V [mm / sec], the maximum adhesion amount per unit area of the toner image formed on the image carrier is M [mg / cm ² ], and the direction orthogonal to the moving direction of the image carrier The maximum width of the toner image is L [mm], the developer movement amount in the rotation axis direction of the developer carrier by the first stirring member is W [g / sec], and the rotation speed of the first stirring member is R [rpm]. When W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus.

(9) 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 the cleaning means as the development means In an image forming apparatus having a toner recycling means for supplying and recycling to
The developing device according to any one of (1) to (7) is used as the developing unit, and the developing device is on a cover of the developing device and between the second stirring member and the third stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner at a corresponding position.

  (10) The image forming apparatus according to (9), wherein the recycled toner supply port is located upstream of the toner supply port in the developer transport direction by the second stirring member.

  According to the developing device of the present invention, for example, the developer is circulated in the direction of the rotation axis of the developer carrier while stirring the developer with two stirring members (first stirring member, second stirring member). This is a configuration that balances the conveyance speed or conveyance amount, stirs the developer in the circumferential direction without substantially conveying the developer in the rotation axis direction by the third agitating member, and raises the charge of the toner in the developer. In addition, sufficient stirring time can be ensured without lowering the developer conveying speed.

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

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

  In other words, since uniform replenishment of the replenishment toner in the developer can be performed quickly, the desired charge amount can be easily imparted to the toner via the circulation conveyance.

  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 of the present invention, 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 operating conditions. The developer charged in a state in which the toner has a desired charge amount is supplied to the developer carrier at a uniform density in the rotation axis direction, and the latent image on the image carrier is developed with the developer. The

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

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

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

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

  The image forming apparatus according to the first embodiment includes an automatic document feeder 1 at the top of the apparatus main body, and includes an image reading unit 2, an image forming unit 3, a belt setting unit for the belt unit 4, and a paper feeding unit. 5, a fixing device T, a reverse discharge / refeed unit 6, and an ADU 7 as reverse transfer means.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  Since the mechanical configuration of the four sets of 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 the image area where the toner image (Y) is present, and a superimposed color toner image is formed on the intermediate transfer belt 401.

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

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

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

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

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

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

  Note that an appropriate transfer bias voltage is applied between the transfer roller 510 and the backup roller 410 at the time of transfer.

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

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

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

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

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

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

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

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

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

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

  In 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 agitating member 803 rotatably disposed at a position adjacent to the longitudinal direction of the developer carrying member 800 (rear side), and the first stirring member 803. A second stirring member 805 rotatably disposed at a position adjacent to the longitudinal direction of the stirring member 803 (rear side), and a predetermined region in the longitudinal direction of the second stirring member (developer transport by the second stirring member) And a rotatable third stirring member 807 provided at a position adjacent to (rear side) of an upstream position in a direction and corresponding to a protruding area 802 described later), and these members are parallel to each other in the axial direction. It has a housing 810 that supports the shaft while maintaining a state, and a cover 812 that can be opened and closed to cover the top of the housing.

  Further, the first stirring member 803 and the second stirring member 805 are configured to be longer than the length of the developer carrier 800.

  Then, by positioning one end position of both agitating members in substantially the same plane as the end position of the developer carrier, the housing 810 and the end of the developer carrier 800 on the other side. Is also protruding.

  In other words, as shown by the arrow in FIG. 2, the first agitating member 803 extends and protrudes downstream in the developer conveyance direction. Reference numeral 802 indicates a protruding region.

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

  Reference numeral 808 denotes a partition wall formed by raising from the bottom of the housing 810, and is located between the first stirring member 803 and the second stirring member 805, and both end portions are missing and are used for developer circulation. Passages 820 and 821 are formed.

  Further, as shown in FIG. 3, the developer carrier 800 and the first stirring member 803 are stored in a developer storage stirring portion (hereinafter referred to as a first storage stirring portion) 815 formed in the housing 810. In addition, the second stirring member 805 and the third stirring member 807 are another storage stirring unit (hereinafter referred to as a second storage stirring unit) 816 formed adjacent to the first storage stirring unit 815. Is housed in.

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

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

  In the present embodiment, the developer carrying member 800 disposed to face the already-exposed photoconductive drum 310 is counterclockwise (the photoconductive drum is opposite to the photoconductive drum in the opposite direction), and the first stirring member. Reference numeral 803 denotes a counterclockwise direction, the second stirring member 805 rotates clockwise, and the third stirring member 807 rotates counterclockwise.

  The first agitating member 803 and the second agitating member 805 are preferably constituted by a rotating member having a high developer conveying capability in the rotation axis direction from the viewpoint of preventing occurrence of toner density unevenness in the rotation axis direction.

  For example, as schematically shown in FIG. 5, the rotary member is formed of a spiral rib (screw) formed with a predetermined orientation in the axial direction and a predetermined pitch p over the entire circumference of the outer peripheral surface of the shaft. be able to.

  In order to circulate the developer, the end portions (portions corresponding to the passages 820 and 821) on the downstream side in the developer transport direction of the first and second stirring members have a predetermined length and width. The blade member is formed so as to protrude from the rotating shaft and has a paddle shape, but this configuration is well known, and its structure is not directly related to the invention, so it is omitted in the drawing. The number of blade members in the circumferential direction of the rotating shaft can be determined as appropriate.

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

  Returning to FIG. 2, the thick arrows indicate the transport direction of the developer when the first stirring member 803 and the second stirring member 805 are rotated in the above-described direction, and the length of the arrow indicates the developer transport capability ( Developer transport speed, developer transport amount, etc.).

  The developer transport direction will be described. The rotation of the first stirring member 803 transports the developer in the first direction (in the drawing, the rotation axis direction from the upper side to the lower side), and the second stirring member 805 is rotated. The rotation conveys the developer in the direction opposite to the conveyance direction by the first stirring member 803 (in the drawing, the rotation axis direction from the lower side to the upper side).

  The rotation of the third stirring member 807 has the ability to stir the developer in the circumferential direction of the rotating shaft, but the ability to transport the developer with respect to the rotating shaft direction is substantially zero.

  For example, as shown in FIG. 6, the third stirring member 807 is configured as a rotating member formed by inclining a plurality of plate-like members 851 with respect to an axis (rotating shaft) J in the same direction at a predetermined angle. Can do.

  Regarding the developer conveying ability, the first stirring member 803 and the second stirring member 805 have substantially the same conveying ability, and the third stirring member 807 is substantially zero.

  The conveying ability of each stirring member is set so as to satisfy the operating conditions of the image forming apparatus described later.

According to the developing device having the above-described configuration, the developer in the first storage stirring unit 815 is conveyed in the axial direction indicated by the arrow while being stirred in the circumferential direction of the rotation axis J by the rotation of the first stirring member 803. In addition, the second storage agitation unit 816 is sent through the passage 821.

  The developer in the second storage agitation unit 816 is conveyed in the direction opposite to the conveyance direction by the first agitation member while being agitated in the circumferential direction of the rotation axis J as the second agitation member 805 rotates, and the partition plate It is sent to the first storage agitation unit 815 via a passage 820 formed at the end of 808 and is circulated and conveyed in a state where it receives the action of the first agitation member 803 again.

  Further, the developer that receives the action of the third stirring member 807 is stirred in the circumferential direction of the rotation axis J to promote the rising of the charge, and is sequentially subjected to the action of the second stirring member 805 described above.

  Note that the developer containing toner that has reached a predetermined charge amount due to the mixing / stirring action during the circulation and conveyance is transported by the first agitating member 803 on the peripheral surface of the developer carrier 800 and the shaft. The toner in the developer is consumed for the visualization.

  The developer on the developer carrier 800 is automatically removed from the developer carrier by the action of a repulsive magnetic field after passing through the development region.

  At this time, since the first stirring member 803 and the developer carrier 800 are rotated in the opposite direction (axis) at the closest point, the removed toner is not immediately supplied to the developer carrier 800. The first agitating member 803 receives the stirring and conveying action, is taken into the circulation channel, and obtains the desired charge amount while being conveyed through the circulation and conveyance route, and is used for the development processing. Become.

  In other words, the developer supplied to the developer carrier 800 by the first agitating member 803 and the first agitating member 803 are set by rotating the developer carrier 800 and the first agitating member 803 as described above. Therefore, it is possible to reliably replace the developer collected in this way, and therefore, the toner density of the developer in the axial direction of the developer carrier 800 can be kept uniform, thereby reducing the occurrence of image density unevenness. it can.

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

  The toner supply port 813 has a substantially intermediate position where the second stirring member 805 and the third stirring member 807 face each other (as shown in the side sectional view of FIG. 4, the second stirring member 805 and the third stirring member 807). Is provided on the cover 812 corresponding to an appropriate position on the upstream side in the developer transport direction by the second stirring member.

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

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

  The supplied toner is efficiently stirred with the developer by the rotation of the second stirring member 805 and the third stirring member 807.

  That is, the second agitating member 805 and the third agitating member 807 are rotated in such a manner that the peripheral surfaces move in the forward direction from the upper side toward the lower side (for example, from the screw). When the attention is paid to one point on the peripheral surface of the stirring member, it means that the one point reaches the proximity point from above with respect to the proximity point and rotates around the axis so as to come out downward) The toner can be quickly submerged in the developer, and the toner can be rapidly and uniformly dispersed in the developer.

  As described above, by making the developer conveying capabilities of the first agitating member 803 and the second agitating member 805 substantially the same, it is possible to suppress the occurrence of developer stagnation on the circulation conveying path and to smoothly circulate the developer. Can be done.

  Further, the operation of imparting a predetermined charge amount to the toner can be promoted through sufficient mixing and stirring operation by the third stirring member 807 without reducing the developer conveyance speed.

  Furthermore, 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. .

  As is clear from the above, the first stirring member 803 in the present embodiment has a function of supplying the developer to the developer carrier 800 and the developer after development removed from the developer carrier 800. It can also be said that the developer supply and recovery member has a function of recovering the toner.

  The toner that is a component constituting the developer preferably has a volume average particle diameter of 3 to 5 μm. Such a small particle diameter toner is a toner having high resolution and excellent fine line reproducibility. An image can be formed, and a stable toner image without image density unevenness can be formed in a solid portion (solid image portion) or a halftone portion.

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

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

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

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

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

  When the developer movement amount (developer transport amount) W in the rotation axis direction by the first agitating member 803 is excessively small, the developer in the developer supply region downstream of the first agitating member 803 in the developer transport direction. Therefore, it becomes difficult to supply a sufficient amount of toner to the developing area, and image density unevenness is likely to occur.

  In addition, when the rotation speed of the first stirring member 803 is excessive, the developer is likely to be deteriorated by heat generated in the shaft portion of the first stirring member 803, and a high-quality image is formed over a long period of time. Difficult to do.

  In other words, by performing the development process in a state where the specific conditions (a) and (b) described above are satisfied, the developer can be supplied to the development area in the axial direction without toner density unevenness. Therefore, an image having a uniform image density without image density unevenness can be obtained.

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

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

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

  In the above, one embodiment of the developing device and the image forming apparatus according to the present invention has been described. However, the first stirring member, the second stirring member, and the third stirring member in the developing device are all limited to those having the above-described configuration. For example, the second agitating member has a developer conveying capability equivalent to that of the first agitating member, and the third agitating member substantially has a developer conveying capability in the axial direction. What is necessary is just to be able to achieve an intended purpose, such as the structure which is zero.

  For example, a stirring member (rotating member) having a configuration schematically shown in FIGS. 7 to 9 can be used as the first stirring member and the second stirring member.

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

  The stirring member shown in FIGS. 7 to 9 has the same basic structure as the stirring member shown in FIG. 5, but has a further increased developer stirring ability, and causes uneven toner density in the axial direction. It has sufficient developer transport capability that is required to prevent this.

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

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

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

  The stirring member shown in FIG. 8 includes a spiral rib 850 formed over the entire outer peripheral surface of the rotating shaft J and with a pitch p having a predetermined size in the axial direction, and is provided at the outer peripheral edge of the spiral rib. Is formed with a notch 857 extending in the axial direction.

  For example, when the figure is viewed from the side, the row of the notches 857 has a configuration of two rows that are 180 degrees out of phase 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.

  The agitating member shown in FIG. 9 rotates over the entire outer peripheral surface of the rotating shaft J and through the spiral rib 850 formed at a predetermined pitch p in the axial direction and the outer peripheral edge of the spiral rib. And plate-like ribs 858 extending linearly in the direction of the axis J. In this example, the ribs are provided at two locations (upper edge portion and lower edge portion in the figure) that are the objects of the axis.

According to the developing device provided with these agitating members, basically, a sufficiently large developer conveying speed can be obtained, and the toner concentration with respect to the axial direction of the developer supplied to the developer carrying member. The occurrence of unevenness can be prevented, and sufficient charge rising characteristics of the toner can be reliably obtained, so that problems such as toner scattering and fogging due to poor charging can be reduced and suppressed.
In the process of transporting the developer in the axial direction by rotating around the rotation axis J, the spiral rib 850 stirs in the circumferential direction, and the plate-shaped rib 858 as an auxiliary stirring member also in the circumferential direction. Stir.

  FIG. 10 shows another configuration example that can be used as the third stirring member.

  The 3rd stirring member which consists of a rotation member shown in the figure is on the outer peripheral surface of the rotating shaft J, and has the structure which formed the plate-shaped rib 852 linearly along the axial direction.

  The third agitating member of the illustrated configuration has a cross paddle shape in which the rib 852 is provided at four locations equally dividing the circumferential direction of the rotation axis J, as long as the intended purpose can be achieved. Well, the design freedom is wide.

  The third stirring member according to the present invention preferably has a higher developer stirring ability from the viewpoint that sufficient charge rising characteristics of the toner can be obtained, and is more preferable with reference to FIGS. 11 and 12 below. A configuration example is shown.

  The third stirring member shown in FIG. 11 includes a plurality of plate-like members 851 made of an ellipse, and four plate-like ribs 858 that support the plate-like member through engagement with the peripheral edge of the plate-like member 851. , Disk-shaped flanges 853 provided at both ends so as to be engaged with the end portions of the plate-like ribs 858 and holding the ribs, and a rotation shaft (not shown) extending outward from the center portion of the flange 853 ) And the main element.

  The plate-like members 851 have an inclination of a predetermined angle α with respect to the rotation center (axis), and are arranged in the axial direction with a predetermined pitch p.

  The external parts after assembling the plate-like member 851, the flange 853, and the rib 858 have substantially the same surface without unevenness.

  The third stirring member configured as described above stirs the developer in the circumferential direction by the plate-like member 851 and rotates the developer by the plate-like rib 858 when rotating around the rotation axis.

  The third agitating member shown in FIG. 12 is engaged with the end portion of the rotating shaft J and has two disk-like flanges 853 that hold the rotating shaft, and at equal intervals in the circumferential direction of the flange 853. The main elements are the four plate-like ribs 858 arranged and a plurality of plate-like members 851 supported by the ribs 858 in a state where the rotation axis J penetrates along a plane perpendicular to the rotation axis J. .

  The plate-like member 851 is made of a disc having a notch portion 854 having a predetermined size except for a predetermined region at the center portion that fits with the rotation shaft.

  The plate-like members 851 are positioned so as to alternately occupy opposite positions with respect to the rotation axis J, and are arranged in the axial direction with a predetermined pitch p.

  The size of the area of the plate-like member in contact with the developer, the pitch p, the size of the area of the plate-like rib 858 in contact with the developer, etc. in FIG. 11 and FIG. Can do.

  In addition, according to the developing device including the third stirring member having such a configuration, the above-described operations and effects can be obtained more reliably, and further reduction of toner scattering and fogging due to toner charging failure can be expected. In addition, the occurrence of uneven image density due to non-uniformity of the toner density in the axial direction of the developer supplied to the developer carrier can be similarly reduced.

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

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

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

  The image forming apparatus shown in FIG. 13 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. 13 is composed of a monochrome digital copying machine, and includes a basic configuration as a copying machine, for example, an automatic document feeder, an image reading unit, an image forming unit, a paper feeding unit, a fixing device, and the like. However, these can be understood from the drawings and explanations relating to the first embodiment, and the developing device 8 has basically the same configuration as that of the first embodiment. The main parts are only shown schematically.

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

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

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

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

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

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

  The 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 second stirring member 805 and the third stirring member 807 are opposed to each other, and the toner supply port 813 is viewed in the developer transport direction by the second stirring member 805. It is provided on the cover 812 corresponding to an appropriate position on the upstream side.

  The positional relationship between the toner supply port 813 and the recycled toner supply port 825 in the longitudinal direction of the developing device 8 is basically shown in FIG. 14, which is a schematic diagram of the same developing device as shown in FIG.

  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.

  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 the recycle toner, which has poor fluidity and low chargeability compared to the new toner, into the developer, and the mixing and stirring time. Therefore, it is possible to obtain a desired charge even for recycled toner, to suppress the occurrence of fog and toner scattering due to poor charging of the toner, and to suppress the occurrence of image density unevenness in image formation. Can do.

  Specifically, in the process in which the developer is transported in the axial direction by the second stirring member 805, a sufficient mixing and stirring time is secured in the second storage stirring unit 816 without reducing the transport speed of the developer, The developer charged so that the toner has a desired charge can be supplied to the developer carrier 800 with a uniform toner concentration in the axial direction by the first stirring member 803.

  Further, since the recycled toner is introduced from the recycled toner supply port 825 provided on the upstream side of the toner supply port 813 in the developer transport direction by the second agitating member 805, the low-charged recycled toner is developed first. After being dispersed in the agent, the new toner can be dispersed, and a long mixing and stirring time for the recycled toner can be secured.

  Accordingly, 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 toner supply including recycled toner are repeatedly performed by continuously outputting images 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.

  In the above description, the main components of the developing device in the first embodiment are the developer carrier and the first to third stirring members. However, the schematic diagram of FIG. 15 and AA of FIG. As shown in the second embodiment of the developing device shown in FIG. 16 which is a cross section, in addition to the first embodiment, the developer carrying member 800 and the first agitating member 803 are further movable. A rotating developer supply / recovery member 809 may be provided.

  In the above configuration, the rotation direction of the developer carrier 800 is counterclockwise, the rotation direction of the developer supply / recovery member 809 is counterclockwise, and the rotation directions of the first stirring member 803 and the second stirring member 805 are clockwise. Yes, the rotation direction of the third stirring member (not shown) is the same as the rotation direction in the first embodiment, and the peripheral surfaces of the third stirring member (not shown) are directed from the top to the bottom at a point close to the second stirring member 805. The shaft is rotated in the direction of movement.

  The above configuration scoops up the developer that is circulated and transported containing the toner having a desired charge amount from the first agitating member 803 with the developer supply / recovery member 809, and the shaft on the developer carrier 800. As well as supplying the developer in the direction, the operation of guiding the developer removed from the developer carrier 800 to the circulation conveyance path via the first stirring member 803 can be smoothly performed.

  The developer supply / recovery member 809 can basically have the same configuration as the stirring member shown in FIG. 10, but the configuration shown in FIG. 6, the configuration shown in FIGS. The configuration and the like are not limited.

  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.

  In addition, regarding 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 described below, rotating members used as the first stirring member, the second stirring member, the third stirring member, and the developer supply and recovery member 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 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 (t): 3 mm, plate -Shaped rib thickness: 1 mm, plate-shaped rib mounting location: two axial targets (rotating member LL)
The rotating member KK has the same configuration as the rotating member KK except that the radial length (t) of the plate-like rib is 5 mm.
(Rotating member MM) A rotating member having the same configuration as the rotating member KK except that four plate-like ribs are provided at equal intervals on the outer peripheral edge of the spiral rib in the rotating member KK.
(Rotating member WW)
As shown in FIG. 6, a first stirring unit and a second stirring unit configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member. And a rotating member having a disk-like flange member having an outer dimension of 24 mm at both ends of the rotating member.

  The specifications of the rotating member WW are as follows.

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

  The specifications of the rotating member XX are as follows.

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

  The specifications of the rotating member QQ are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 360 mm, outer diameter of the shaft member: 6 mm, thickness of the plate member: 1 mm
(Rotating member Q)
The rotating member QQ has the same configuration as the rotating member QQ except that the axial length excluding the shaft portion is 110 mm.
(Rotating member R)
As shown in FIG. 12, a plurality of plate-like members made of disks provided so that the notches are alternately opposite to each other, and four axial positions provided at equal intervals in the circumferential direction of the plate-like member. A rotating member having a plate-like rib member extending continuously and 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 R are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 110 mm, outer diameter of the shaft member: 6 mm, thickness of the plate-like member: 1 mm, attachment angle 90 ° with respect to the shaft of the plate-like member, plate-like Arrangement pitch of members: 25 mm, Mounting angle (center angle) of plate-like member: 270 °, radial length of plate-like rib (t): 5 mm, thickness of plate-like rib: 1 mm, attachment of plate-like rib Location: 4 locations (equal intervals in the circumferential direction)
(Rotating member S)
As shown in FIG. 6, it has a configuration in which a plurality of plate-like members having an elliptical shape in the axial direction are arranged, and a configuration in which disc-shaped flange members having an outer dimension of 24 mm are provided at both ends of the rotating member. Rotating member.

  The specifications of the rotating member S are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 110 mm, outer diameter of the shaft member: 6 mm, thickness of the plate member: 1 mm, attachment angle 45 ° with respect to the shaft of the plate member, plate shape Arrangement pitch of members: 25mm
(Rotating member T)
As shown in FIG. 11, a plurality of elliptical plate-like members are arranged in the axial direction, and provided with plate-like ribs extending in the axial direction at equal intervals in the circumferential direction, and both ends of the rotating member A rotating member having a configuration in which a disc-shaped flange member having an outer dimension of 24 mm is provided in the part.

  The specifications of the rotating member T are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 110 mm, outer diameter of the shaft member: 6 mm, thickness of the plate member: 1 mm, attachment angle 45 ° with respect to the shaft of the plate member, plate shape Arrangement pitch of members: 25 mm, radial length of plate-like rib (t): 3 mm, thickness of plate-like rib: 1 mm, attachment location of plate-like rib: 4 (equally spaced in the circumferential direction)
<Experimental example 1>
[Create developer]
In accordance with the configuration shown in FIGS. 2 to 4, developing devices 1 to 6 according to the present invention in which the first stirring member, the second stirring member, and the third stirring member are constituted by rotating members shown in Table 1 below were produced.

  Further, the winding direction of the spiral rib is right-handed, and the second stirring member and the third stirring member are rotated in such a manner that the peripheral surfaces of the second stirring member and the third stirring member move from the lower side to the upper side at the proximity point of both. A comparative developing device 7 having the same configuration as that of the developing device 1 was prepared except that the direction was reversed.

  Further, as shown in FIG. 18, the structure is the same as that shown in FIG. 2 except that the third stirring member is not provided, and the first stirring member and the second stirring member are shown in Table 1 below. Development devices 8 to 17 for comparison were produced using rotating members selected according to the combinations shown.

  Further, as shown in FIG. 15, a developer supply / recovery member is provided between the first stirring member and the image carrier, and the developing device according to the present invention in which the rotation direction is set as shown in FIG. 18 to 22 and comparative developing devices 23 to 25 having the same configuration as the developing devices 18 to 22 were prepared except that the third stirring member was not included.

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

  The toner supply port is formed in each of the developing devices 1 to 6 and 18 to 22 according to the present invention at a position where the second stirring member and the third stirring member face each other (cross section perpendicular to the longitudinal direction). When viewed, the upper position in the middle of both members is a position 15 mm downstream from the upstream edge in the developer transport direction by the second stirring member.

  On the other hand, the formation position of the toner supply port in each of the developing devices 7 to 18 and 23 to 25 for comparison is an upper position on the rear side of the second stirring member, and is in the developer transport direction by the second stirring member. It is a position 15 mm downstream from the upstream edge.

  As the developer, a two-component developer having a toner concentration of 7% by mass was used for any of the developers related to yellow toner, magenta toner, cyan toner, and black toner.

  The developer loading amount is 850 g for the developing devices 1 to 7, 750 g for 8 to 17, 1100 g for 18 to 22, and 1000 g for 23 to 25.

  Each of the above toners has a volume average particle diameter of 4.5 ± 0.15 μm, a CV value [a / b × 100%] indicated by the standard deviation (a) of the particle diameter distribution and the average particle diameter (b). In each color polymerized toner having a toner particle size of 18 ± 2%, large particle size silica 0.8% by mass, small particle size silica 0.2% by mass, large particle size titania 0.2% by mass, 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 7 and the comparative developing devices 8 to 18 according to the present invention is mounted on an appropriate driving machine, and the rotation amounts of the first stirring member, the second stirring member, and the third stirring member are shown in the following table. 1 was set, and the developer movement amount was measured.

  The results are shown in Table 1 below.

  Note that the developer movement amount is measured by driving another rotating member without driving the developer supply / recovery member and the developer carrying / recovering member when the developer carrier and developer supply / recovery member are present. This was performed by measuring the weight of the developer discharged per unit time from the developer discharge port provided on the bottom surface of the housing on the downstream side of the first stirring member in the direction.

  In Table 1, the “rotation direction” related to the first agitating member is the moving direction when viewed from the position close to the developer carrying member in the developing devices 1 to 17, and there is a developer supply / recovery member. In the developing devices 18 to 25, the moving direction when viewed from the position close to the developer supply / recovery member is shown.

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

  Further, for example, two types of rotation speeds of the first stirring member in the developing devices 1 to 6 are displayed. 300 rpm is the rotation speed in color image formation, and 400 rpm is the rotation speed in monochrome image formation. This relates to Table 2 and Table 3.

[Image forming apparatus]
According to the configuration shown in FIG. 1, an image forming apparatus for forming a color image on which each of the developing devices 1 to 25 is mounted was manufactured, and an image output test was performed under the following image forming conditions.

The image forming conditions were set to be the same for all of the image forming units related to the respective color toner images.
<Image forming conditions>
-Process speed (V): 220 mm / sec (number of images formed per minute is 50)
Rotational speed of first, second, third, and developer supply / recovery members: 300 rpm for developing devices 1-6, 400 rpm for developing devices 7-25
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
Charging potential (VH): Control was made so that VH = Vdc−150 V according to the set value of the DC bias component in the developing bias.

In the image output test, the image output of the following (1) to (6) is repeated four times (A4 × 2000 in total), the presence / absence of fogging of the character / line pattern, the presence / absence of character scattering, the density of the solid pattern The presence / absence of unevenness and the presence / absence of in-machine contamination were evaluated based on the following evaluation criteria. The results are shown in Table 2 below.
(1) Cyan (C) monochromatic characters / lines + halftone (10 steps) pattern (printing rate 30%) are output in succession 50 sheets.
(2) Cyan (C) single color solid pattern (printing rate 80%) is output continuously 150 sheets.
(3) Cyan (C) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets.
(4) Blue (magenta (M) + cyan (C)) single-color character / line + halftone (10 steps) pattern (printing rate of 30% for both M and C) is output in 50 sheets.
(5) Continuous output of 150 solid blue solid patterns (printing rate of 80% for both M and C).
(6) Output 50 sheets of blue (magenta (M) + cyan (C)) single color characters / line patterns (printing rate 7% for both M and C) continuously.

<Evaluation criteria>
(B) Image cover:
For image fogging, the relative reflection density of the white portion of the character / line pattern when the reflection density of unused paper is 0 is measured. If the relative reflection density is 0.004 or less, “○” is given. The case where the reflection density exceeded 0.004 and was 0.006 or less was evaluated as “Δ”, and the case where the relative reflection density exceeded 0.006 was evaluated as “x”.
(B) Letter scattering:
For character scattering, the sharpness of the character outline and the state of the bleeding of the character when the 4-point “bell” character was observed in an enlarged manner were evaluated.

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

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

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

  The developing device numbers in Table 2 correspond to the developing device numbers in Table 1, and as described above, the rotation speeds of the first and second stirring members constituting the developing devices 11 to 17 are 300 rpm. is there.

<Experimental example 2>
[Production of development device]
In each of the developing devices 1, 2, 4, 8 to 20, and 23 to 25 used in Experimental Example 1, the recycled toner is disposed at a position 8 mm upstream from the toner supply port in the developer transport direction by the second stirring member. Development devices having supply ports (development device numbers in all tables are unified for easy understanding) 1, 2, 4, 8-20, 23-25 were prepared.

  In the configuration shown in FIG. 13, an image forming apparatus for forming a monochrome image having toner recycling means on which each of the developing devices 1, 2, 4, 8 to 20, and 23 to 25 is mounted was manufactured.

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

Then, the process speed of the image forming apparatus is set to 320 mm / sec (the number of image forming sheets per minute is 65), and the first stirring member, the second stirring member, the third stirring member, and the developer supply / recovery The rotational speed of each of the members was set to 400 rpm for the developing devices 1, 2, 4, 8 to 10, 18 to 22, and 23 to 25, and 650 rpm for each of the developing devices 11 to 17, and Experimental Example 1 The image output test is repeated eight times under the same image forming conditions as the image forming unit for the black (BK) toner image (A4 × 2000 sheets in total). The evaluation of the presence / absence of fogging of characters / line patterns, the presence / absence of character scattering, and the presence / absence of in-machine contamination is performed 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 5 below.
(7) Black (BK) single color characters / lines + halftone (10 steps) pattern (print rate 30%) are output in succession 50 sheets.
(8) Continuously output 150 black (BK) solid patterns (printing rate 80%).
(9) Black (BK) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets.
<Evaluation criteria>
The image density unevenness is measured by measuring the relative reflection density at any nine locations in the black (BK) solid pattern page, the relative reflection density at all locations is 1.3 or more, and the maximum and minimum values. The case where the difference is 0.1 or less is “◯”, 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 “△”, and the case where the minimum value of the relative reflection density is less than 1.2 or the difference between the maximum value and the minimum value exceeds 0.15 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.

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

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

  In particular, in an image forming apparatus equipped with a toner recycling unit, the rotation speed of the rotating member is increased to obtain a sufficient developer moving speed, thereby preventing the occurrence of uneven image density in the axial direction. The image output test had to be stopped due to a significant increase in the stirring torque, and an output image could not be obtained. 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 a schematic diagram which shows the other example of a stirring member. It is the schematic which shows 2nd Embodiment of an image forming apparatus. FIG. 4 is a schematic diagram of a developing device for explaining a positional relationship between a toner supply port and a recycled toner supply port. It is a schematic diagram which shows 2nd Embodiment of a developing device. It is AA sectional drawing of FIG. It is the schematic which shows one structural example of the stirring member used in the experiment example. 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 means 810 Housing 812 Cover 813 Toner supply port

Claims (10)

A developer carrying member for carrying and conveying a developer including toner and a carrier, a first stirring member provided adjacent to the longitudinal direction of the developer carrying member and stirring the developer in a predetermined direction; A second stirring member that is provided adjacent to the longitudinal direction of the first stirring member and that stirs while transporting the developer in a direction opposite to the transport direction of the developer by the first stirring member; and the developer carrier, A housing for rotatably supporting the first stirring member and the second stirring member; and a cover provided on an upper portion of the housing; and a partition wall is provided between the two stirring members. In the developing device configured to circulate and convey the developer stored in the storage stirring portion by the first stirring member and the second 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 protrude from the end of the developer carrier. With
A third stirring member whose length in the rotation axis direction is shorter than that of the second stirring member and whose developer conveying ability in the rotation axis direction is substantially zero is set in the developer conveying direction by the second stirring member. Is provided opposite to the second stirring member on the upstream side,
The second stirring member and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable from above to below,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side when the second stirring member and the third stirring member are opposed to each other in the developer transport direction by the second stirring member. With a mouth,
A developing device. A developer carrying member for carrying and conveying a developer including toner and a carrier, a first stirring member provided adjacent to the longitudinal direction of the developer carrying member and stirring the developer in a predetermined direction; A second stirring member that is provided adjacent to the longitudinal direction of the first stirring member and that stirs while transporting the developer in a direction opposite to the transport direction of the developer by the first stirring member; and the developer carrier, A housing for rotatably supporting the first stirring member and the second stirring member; and a cover provided on an upper portion of the housing; and a partition wall is provided between the two stirring members. In the developing device configured to circulate and convey the developer stored in the storage stirring portion by the first stirring member and the second 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 protrude from the end of the developer carrier. Along with the spiral rib formed in the direction of the rotation axis,
Developing a third stirring member having a length in the rotation axis direction shorter than that of the second stirring member and comprising a plurality of plate-like members inclined in the same direction with respect to the rotation axis by the second stirring member. Provided facing the second stirring member on the upstream side in the agent transport direction,
The second stirring member and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable from above to below,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side when the second stirring member and the third stirring member are opposed to each other in the developer transport direction by the second stirring member. With a mouth,
A developing device. A developer carrying member for carrying and conveying a developer including toner and a carrier, a first stirring member provided adjacent to the longitudinal direction of the developer carrying member and stirring the developer in a predetermined direction; A second stirring member that is provided adjacent to the longitudinal direction of the first stirring member and that stirs while transporting the developer in a direction opposite to the transport direction of the developer by the first stirring member; and the developer carrier, A housing for rotatably supporting the first stirring member and the second stirring member; and a cover provided on an upper portion of the housing; and a partition wall is provided between the two stirring members. In the developing device configured to circulate and convey the developer stored in the storage stirring portion by the first stirring member and the second 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 protrude from the end of the developer carrier. Along with the spiral rib formed in the direction of the rotation axis,
A third stirring member including a plate-like rib having a length in the rotation axis direction shorter than the second stirring member and extending in the rotation axis direction with a gap between the rotation shaft and the rotation shaft; 2 provided opposite the second stirring member on the upstream side in the developer conveying direction by the stirring member,
The second stirring member and the third stirring member are viewed at their opposing proximity points, and the peripheral surface is movable from above to below,
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side when the second stirring member and the third stirring member are opposed to each other in the developer transport direction by the second stirring member. With a mouth,
A developing device. 4. The developing device according to claim 1, wherein the developer carrying member and the first agitating member move in directions opposite to each other when viewed from their proximity points. 5. A developer conveyed by the first stirring member is supplied to the developer carrying member between the developer carrying member and the first stirring member, and from the developer carrying member toward the first stirring member. A rotatable developer supply and recovery member for recovering the developer is provided; and
4. The developing device according to claim 1, wherein the developer supply / recovery member and the developer carrying member move in directions opposite to each other when viewed from their proximity points. 5. . 6. The developing device according to claim 5, wherein the peripheral surface of the first agitating member is moved from the lower side toward the upper side when viewed from a proximity point between the developer supply and recovery member and the first agitating member. . 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 a toner and a carrier is used. An image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image into a toner image.
While using the developing device of any one of Claim 1 thru | or 7 as said image development means,
The moving speed of the image carrier is V [mm / sec], the maximum adhesion amount per unit area of the toner image formed on the image carrier is M [mg / cm ² ], and the direction orthogonal to the moving direction of the image carrier The maximum width of the toner image is L [mm], the developer movement amount in the rotation axis direction of the developer carrier by the first stirring member is W [g / sec], and the rotation speed of the first stirring member is R [rpm]. W ≧ M · V · L / 1000
R ≦ 600
An image forming apparatus. An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier Transfer means for transferring an image to a transfer material or intermediate transfer member, cleaning means for cleaning the surface of the image carrier after transfer, and toner removed from the surface of the image carrier by the cleaning means are supplied to the developing means. In an image forming apparatus having toner recycling means for recycling
The developing device according to any one of claims 1 to 7 is used as the developing unit, and the developing device is on a cover of the developing device and corresponds to between the second stirring member and the third stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner at a position. 10. The image forming apparatus according to claim 9, wherein the recycled toner supply port is located upstream of the toner supply port in the developer transport direction of the second stirring member.

Images