JP2005345858A - Development device and image-forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development device capable of easily imparting a predetermined charge amount to the toner, capable of suppressing spillover of the developer, and capable of forming images of high image quality, while having a simple constitution, without causing the developer conveyance speed to be reduced. <P>SOLUTION: The developing device 8 comprises a developer carrier 800 which has a magnetic field generating means fixed therein and bears and conveys a developer including a toner and carrier; a first stirring member 803 disposed adjacently in a rotating shaft direction of the developer carrier; a second stirring member 805 disposed adjacent in a rotating shaft direction of the first stirring member so as to convey the developer in a direction opposite to a direction of developer conveyance by the first stirring member; and a third stirring member 807, disposed next to the second stirring member so as to convey the developer in the same direction as the second stirring member, wherein a total amount of the developer conveyed by the second and third stirring members is made larger than the amount of the developer conveyed by the first stirring member on an upstream side so that the amounts are made nearly equal at downstream side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device that visualizes 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.

  Further, as a developing device used in such an image forming apparatus, 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 used. The main component is an agitating member for agitating and imparting an amount of charge necessary for the developing process, and the agitated two-component developer adsorbed by the action of the magnet during the developing process is the peripheral surface of the developer carrying member. In addition, the developer is sequentially conveyed to the development area by the rotation of the developer carrier, and the developer after development processing is automatically performed with the repulsive magnetic field formed by the magnetic pole arrangement of the built-in magnet. A developing device that can be removed from the developer carrying member is also known.

  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 supplied toner is supplied to the development area without having a predetermined charge amount, the image quality is deteriorated by 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.

  There have been many proposals for improving the stirring efficiency of the developer. For example, by providing a member that functions as an auxiliary stirring member in the stirring member or the developer conveying member, the developer has a high developer stirring ability. (For example, refer to Patent Document 1 and Patent Document 2).

Further, the developer carrying body and first and second agitating and conveying screws provided on one side thereof, compared to the developer conveying speed by the first agitating and conveying screw arranged close to the developer carrying body. Thus, a technique for improving the agitation of the developer by a configuration in which the developer conveyance speed by the second agitation conveyance screw is increased has been proposed (see, for example, Patent Document 3).
Japanese Unexamined Patent Publication No. 07-013420 JP 09-166918 A JP 2001-154471 A

  However, the developing devices disclosed in Patent Documents 1 and 2 above 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 decreases, for example, high speed It seems that there is still room for improvement as a developing device used for an image forming apparatus having the above 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 is likely to occur, and it becomes difficult to form a high-quality image.

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

  In addition, the developing device disclosed in Patent Document 3 is easy to configure and is a useful technique. From the second stirring and conveying screw having a high developer conveying speed to the first stirring and conveying screw having a low developer conveying speed. When delivering the developer, there is a problem that the developer stays near the communication port (delivery part) and the developer overflows.

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

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

(1)
A developer carrier having a magnetic field generating means fixedly disposed therein and carrying a developer including toner and carrier;
A first stirring member provided adjacent to the rotation axis direction of the developer carrier;
The first stirring member to transport the developer in a direction farther from the first stirring member relative to the developer carrying member and in a direction opposite to the developer transport direction by the first stirring member. A second stirring member provided adjacent to the rotation axis direction of
A housing that rotatably supports and accommodates the developer carrier, the first stirring member, and the second stirring member, and has a partition wall between the first stirring member and the second stirring member When,
In the developer circulating type developing device having a cover provided on the upper part of the housing,
The developer conveying capability of the second stirring member is set lower than the developer conveying capability of the first stirring member, and
A third stirring member having a developer conveying ability substantially the same as or lower than that of the second stirring member is provided to be rotatable in opposition to the second stirring member;
The total developer transport amount in the rotation axis direction of the second stirring member and the third stirring member is reduced from the upstream side to the downstream side when viewed in the developer transport direction by the two stirring members. Set and also
The developer transport amount in the rotation axis direction by the first stirring member is set to be substantially the same as the total developer transport amount on the downstream side of the developer by the second and third stirring members,
The second agitating member and the third agitating member are viewed at their opposing proximity points so that the peripheral surface moves downward from above,
When the second stirring member and the third stirring member are viewed from the side, the second stirring member and the third stirring member include a substantially intermediate portion between them, and correspond to an upstream position when viewed in the developer transport direction by the second stirring member. A toner supply port for supplying toner is provided in an area on the cover.
A developing device.

(2)
At least one of the second stirring member or the third stirring member is constituted by a spiral rib formed around the rotation axis, and the pitch of the spiral rib is determined by the developer transport direction by the two stirring members. The developing device according to (1), wherein the developing device is set smaller from the upstream side toward the downstream side.

(3)
At least one of the second stirring member or the third stirring member is composed of a spiral rib formed around the rotation axis and a rod-like or plate-like rib provided between the spiral ribs,
The height or width of the rod-like or plate-like ribs is set to be higher or wider from the upstream side to the downstream side when viewed in the developer conveying direction of the two stirring members. The developing device according to 1).

(4)
At least one of the second stirring member or the third stirring member is formed of a spiral rib having a notch formed around a rotation axis, and the depth or width of the notch is set to the both The developing device according to (1), wherein the developing device is set deeper or wider from the upstream side toward the downstream side as viewed in the developer conveying direction by the stirring member.

(5)
At least one of the second stirring member or the third stirring member includes a spiral rib formed around the rotation axis, and a plate-like rib extending in the rotation axis direction so as to cross the spiral rib. Configure
The developing device according to (1), wherein the width of the plate-like ribs is set wider from the upstream side to the downstream side when viewed in the developer conveying direction of the two stirring members.

(6)
A plurality of plate-like members provided around the rotation axis and inclined in the first direction with respect to the rotation axis, and a plurality of plate-like members provided inclined in the second direction The developing device according to any one of (1) to (5), wherein the developing device includes a member.

(7)
The developer carrying member and the first stirring member have circumferential surfaces that move in directions opposite to each other at opposite points of the developer carrying member and the first stirring member, according to any one of the items (1) to (6). Development device.

(8)
The magnetic field generating means has adjacent repulsive magnetic poles of the same polarity,
The developing device according to any one of (1) to (7), wherein an opposing proximity point between the developer carrier and the first stirring member is substantially between the repulsive magnetic poles.

(9)
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 (8), wherein a developer containing the toner and carrier is used.

(10)
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.
As the developing means, the developing device according to any one of (1) to (9) 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.

(11)
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
While using the developing device according to any one of (1) to (9) as the developing means,
Recycled toner is disposed on the cover of the developing device at a position corresponding to the space between the second stirring member and the third stirring member and corresponding to the upstream side when viewed in the developer transport direction by the two stirring members. An image forming apparatus provided with a recycled toner supply port for supply.

(12)
The image forming apparatus according to (11), wherein the recycled toner supply port is located upstream of the toner supply port as viewed in the developer conveying direction by both stirring members.

  According to the developing device of the present invention, for example, the total developer transport amount in the rotation axis direction of the second stirring member and the third stirring member is viewed from the upstream side when viewed in the developer transport direction by the both stirring members. The amount of developer transported in the rotation axis direction by the first agitating member is set to decrease toward the downstream side, and the developer downstream by the second and third agitating members is almost all over the rotation axis direction. By setting to approximately the same as the total developer transport amount on the side, charging can be performed without causing a decrease in developer transport speed, and developer stagnation in the developer delivery section for circulation is also possible. Since it does not occur, it does not cause an overflow phenomenon.

  Furthermore, since the volume of the developer can be set high on the first stirring member side, the developer can be smoothly supplied from the first stirring member to the developer carrying member. For example, even when the first stirring member has a screw configuration, Image defects associated with pumping up (supplying) developer such as screw pitch unevenness can be suppressed.

  Further, the developer transport amount by the second stirring member and the third stirring member is large in the upstream side (meaning that the transport speed is fast), in other words, the developer volume is on the downstream side. Therefore, the toner to be replenished between the third stirring member and the developer can be quickly sunk into the developer by using the region, and charging of the replenished toner can be easily performed.

  In other words, uniform replenishment of the replenishment toner in the developer can be quickly performed, so that the toner can be easily charged via the circulation conveyance.

  Further, since the toner in the developer can be 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 if there is, high image quality can be maintained.

  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 which is a reverse conveyance unit.

  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 driving of the reversing unit 111 is stopped, and the document reversing unit 111 is immediately rotated in the reverse direction to be again guided to the image reading position via the document conveying unit 105 to be read by the reading device 2. The paper means 107 discharges the original on a document discharge table 109.

  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 charger 320 of scorotron type, an exposure optical system 330 as image writing means, a developing device 8 for visualizing an electrostatic charge latent image formed on the photosensitive drum via the exposure optical system, and visualization A main component is a cleaning device 350 including a transfer unit 340 for transferring the toner image formed on the photosensitive drum onto a transfer material and a blade (cleaning unit) for cleaning the surface of the photosensitive drum 310 after the transfer.

  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 sheet P as a transfer material 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 (front side), and the first stirring member 803. A second agitating member 805 disposed in a rotatable manner with a partition wall 808 sandwiched at a position adjacent to the agitating member 803 in the longitudinal direction (behind the first agitating member with respect to the developer carrying member); A rotatable third stirring member 807 provided at a position adjacent to the longitudinal direction of the second stirring member (behind the second stirring member with respect to the developer carrying member), and these members are pivoted to each other. A housing 810 that supports the shaft while maintaining a parallel state when viewed in the direction, and an openable / closable cover 812 that covers the upper portion of the housing.

  The first stirring member 803, the second stirring member 805, and the third stirring member 807 have substantially the same length in the rotation axis direction, and the length is longer than the length in the rotation axis direction of the developer carrier 800. Is also long.

  Then, by positioning one end position of all the 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 configured to protrude.

  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.

  The partition wall 808 is formed to rise from the bottom of the housing 810, and is positioned between the first stirring member 803 and the second stirring member 805. Passages (also referred to as developer delivery portions) 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 has a function of supplying a developer to the developer carrier 800 and has a developer conveyance capability (development) that does not cause toner density unevenness in the rotation axis direction of the developer carrier. The same as the developer transport speed and developer transport amount).

  The first stirring member 803 has a function of collecting the developer that is automatically removed from the developer carrier 800 by the action of a repulsive magnetic field (described later) after passing through the development region.

  The first stirring member 803 as described above, for example, is formed with a predetermined direction in the axial direction and a predetermined pitch p over the entire circumference of the outer peripheral surface of the shaft (rotating shaft) J, as schematically shown in FIG. It can be configured as a rotating member made of a spiral rib (screw).

  The spiral rib can be basically used for the second stirring member or the third stirring member.

  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. Although the cross-shaped paddle shape is formed by projecting the blade member from the rotating shaft, this configuration is well known, and its structure is not directly related to the invention, so it is omitted in the figure. 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.

  In FIG. 2, the thick arrows shown in the stirring member indicate the developer transport direction when the first stirring member 803, the second stirring member 805, and the third stirring member 807 are rotated in the above directions. The length indicates the developer transport capability (developer transport speed, developer transport amount, etc.).

  The developer transport direction and transport capability 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) at a predetermined transport speed. The rotation of the second agitating member 805 and the third agitating member 807 conveys the developer in the direction opposite to the conveying direction by the first agitating member 803 (rotational axis direction from the lower side to the upper side in the drawing). .

  Thus, the second stirring member 805 in the present embodiment has a transport capability lower than the developer transport capability of the first stirring member 803, and in the developer transport direction by the second stirring member. In view of this, the developer transport capability is configured (set) so as to decrease from the upstream side toward the downstream side.

  In addition, the third stirring member 807 has a transport capability that is substantially equal to or lower than that of the second stirring member 805, and from the upstream side to the downstream side in the developer transport direction by the third stirring member. The developer conveyance capacity is set to decrease as it goes.

  For example, in the case where the second stirring member 805 and the third stirring member 807 are configured using spiral ribs, the pitch (screw pitch) p of the spiral ribs as it goes downstream as viewed in the developer transport direction is set. By reducing the size, the developer conveying ability can be reduced.

  Further, when viewed in terms of the total developer conveying ability by the second stirring member 805 and the third stirring member 807, on the upstream side, the conveying amount higher than the developer conveying amount per unit time of the first stirring member 803. In the vicinity of the downstream end, the amount of developer transported by the first stirring member 803 is substantially the same.

  In other words, the developer conveyance amount in the rotation axis direction of the first agitating member 803 is substantially uniform, and the second and third agitating members of the second and third agitating members are obtained so as to obtain a developer conveyance amount substantially equal to the developer conveyance amount. A downstream configuration is defined.

  With this configuration, it is possible to suppress the phenomenon that the developer stays and overflows in the vicinity of the developer delivery portions 820 and 821, and the toner can be easily charged.

  Furthermore, the above-described effects can be obtained without reducing the developer conveyance speed by the first stirring member 803 set so as not to cause image unevenness.

  The configuration of the second stirring member 805 and the third stirring member 807 in the rotation axis direction may be a configuration in which the developer transport amount is continuously decreased, and each of the second stirring member 805 and the third stirring member 807 is stepped for each predetermined range in the axial direction. Alternatively, the conveyance force may be reduced.

  Furthermore, a setting is made such that either one of the agitating members has a uniform conveying ability in the axial direction that is lower than the conveying ability of the first agitating member. It is also possible to give a gradient to the conveyance capacity, and as a result, the same result as described above can be obtained, and the degree of freedom in design is wide.

  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 sent into the second storage agitation unit 816 is conveyed by the second agitation member 805 and the third agitation member 807 with a total capacity larger than that of the first agitation member 803, and gradually the conveyance speed thereof. (The transport amount per unit time) is reduced, and at the downstream end, the transport speed is substantially the same as the transport speed of the first stirring member 803, and the operation of transporting again by the first stirring member 803 via the transfer unit is repeated. , And is circulated and conveyed in a manner surrounding the partition wall 808.

  The developer containing toner that has reached a predetermined charge amount by the mixing / stirring action during the circulating conveyance is conveyed by the first agitating member 803 in a state where there is no uneven mixing, and the developer carrier 800. Are supplied to the peripheral surface and subjected to development processing, and as a result, a high-quality image without image unevenness is obtained.

  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, the first stirring member 803 and the developer carrier 800 are rotated so that their peripheral surfaces move in opposite directions at the closest point, and the removed toner is immediately supplied to the developer carrier 800. Instead, the first agitating member 803 receives the stirring and conveying action and is taken into the circulation flow path, and obtains the desired charge amount while being conveyed through the circulation conveyance path and used for development processing. Will be.

  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 an intermediate between the portions facing each other) and upstream in the developer transport direction by the second stirring member (in this embodiment, it can be referred to as the third stirring member or both stirring members). It is provided on the cover 812 corresponding to an appropriate position on the side.

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

  The position of the toner supply port 813 is the upstream position as described above, which is intended to obtain an effective mixing and stirring time.

  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 focusing on one point of the peripheral surface of the stirring member, the one point reaches the proximity point from above with respect to the proximity point, and rotates around the axis so as to escape downward), and Since the volume (height) of the developer is lower than that on the first stirring member side, the supplied toner can be quickly submerged in the developer, and the toner is quickly and uniformly dispersed in the developer. Can be made.

  FIG. 6 is a schematic diagram for explaining the positional relationship between the developer carrying member and the first stirring member.

  In the figure, reference numeral 801 denotes a cylindrical magnet built in a fixed position with respect to the developer carrier 800, and magnetic poles S1, N1, S2, N2, and S3 are provided at five locations when viewed in the direction of the developer. Have.

  The magnetic pole S1 attracts the developer supplied by the first stirring member 803 onto the peripheral surface of the developer carrier 800.

  The attracted developer is conveyed by being held on the developer carrier by magnetic poles N1, S2, N2, and S3, and a latent image on a photosensitive drum (not shown) is visualized in the area of the magnetic pole N2.

  Thereafter, the developer conveyed to the vicinity of the magnetic pole S3 through the rotation of the developer carrier is automatically applied from above the developer carrier 800 by the action of the repulsive magnetic field formed by the magnetic pole S3 and the magnetic pole S1. It is dropped and removed, and the first agitating member 803 is rotated away from the vicinity of the developer carrier 800 and directed toward the delivery unit 821.

  In the present embodiment, the angle α between the magnetic poles of S1 and S3 (the angle on the surface of the developer carrying member formed by substantially connecting the center of the developer carrying member and each of the magnetic poles S1 and S3) is 110 degrees.

  Moreover, it has a region where the magnetic attractive force between the repulsive magnetic poles S1 and S3 is 1 gf or less.

  The angle between the magnetic poles is preferably 70 degrees or more, more preferably 90 degrees or more.

  As a result, the surface of the developer carrying member formed by connecting the position at which the magnetic attraction force is 1 gf or less, preferably 0 gf, 20 degrees (substantially the position of the developer carrying member center and the magnetic poles S1 and S3 indicating 1 gf or less is provided. The angle above) can be secured.

  When the angle between the magnetic poles is less than 70 degrees, it is not possible to secure a sufficient area where the magnetic attractive force is 1 gf or less, preferably 0 gf, and the removal of the developer from the developer carrier 800 by the repulsive magnetic field is not possible. In some cases, the developer becomes complete, and the developer after being subjected to development is transported to the development area again, resulting in image density unevenness.

  As described above, the first agitating member 803 is disposed opposite to the developer carrier 800 with a built-in magnet in a region where the magnetic attractive force is 1 gf or less.

  Specifically, in a region on the surface of the developer carrying member where the magnetic attraction force is 1 gf or less, a part of the peripheral surface of the first stirring member takes the closest position to the surface of the developer carrying member. As shown in FIG.

  In the present embodiment, a rotating member having an outer diameter of 24 mm having a helical screw as a main part is used as the first stirring member, and the closest distance is set to 4 mm.

  The closest distance between the developer carrying member 800 and the peripheral surface of the first stirring member 803 is preferably 6 mm or less, and more preferably 5 mm or less.

  If the closest distance exceeds 6 mm, the developer may not be sufficiently supplied and collected between the first stirring member and the developer carrying member, and there is a concern that an uneven image may be formed.

  In addition, the closest distance between the two does not include zero mm, but 2 mm or more is appropriate from the viewpoint of accuracy and the like, and from the viewpoint of developer supply / recovery function, even if a distance of 3 mm is sufficient Can be achieved.

  The toner constituting the developer preferably has a volume average particle size of 3 to 5 μm. Such a small particle size 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], where 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 high-quality image with a uniform image density and fineness 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 of the image carrier [mm / sec], and M is the maximum amount of adhesion per unit area of the toner image formed on the image carrier [mg / cm ^2]. ], L is the maximum width [mm] of the toner image in the direction (axial direction) orthogonal to the moving direction of the image carrier, and W is the developer movement amount in the rotational axis direction of the developer carrier by the first stirring member [g / Sec] and R indicate the rotation speed [rpm] of the first stirring member.

  When the developer movement amount (developer transport amount) W in the rotation axis direction by the first 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.

  Next, other forms of the stirring member having a configuration other than those already described will be described.

  The stirring member shown in FIGS. 7 to 9 is another configuration example that can be suitably used as the second stirring member or the third stirring member, and has the same basic configuration as the stirring member shown in FIG. However, the developer agitating ability is further enhanced, and the developer conveying ability is sufficient to prevent the occurrence of uneven toner density in the axial direction.

  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.

  When used as the second stirring member or the third stirring member according to the present invention, the developer transport amount is changed from the upstream side to the downstream side as viewed in the developer transport direction of the stirring member (the transport amount is As described above, the height (diameter length h) or width (axial length W) of the rod-shaped or plate-shaped rib is increased or increased from the upstream side toward the downstream side. Is set as follows.

  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.

When used as the second stirring member or the third stirring member according to the present invention, the developer transport amount is changed from the upstream side to the downstream side as viewed in the developer transport direction of the stirring member (the transport amount is The circumferential length (width) U or the radial length (depth) t of the notch is set to be wider or deeper from the upstream side toward the downstream side. The stirring member shown in FIG. 9 extends over the entire outer peripheral surface of the rotating shaft J and has a helical rib 850 formed at a predetermined pitch p in the axial direction, and the outer peripheral edge of the helical rib. And a plate-like rib 858 extending linearly in the direction of the rotation axis J. In this example, plate-like ribs are provided at two locations (upper edge and lower edge in the drawing) that are axial objects.

  When used as the second stirring member or the third stirring member according to the present invention, the developer transport amount is changed from the upstream side to the downstream side as viewed in the developer transport direction of the stirring member (the transport amount is The width of the plate-like rib is set so as to increase from the upstream side toward the downstream side when viewed in the developer transport direction of the stirring member.

  According to the developing device in which the stirring members having the configurations shown in FIGS. 7 to 9 are provided as the second stirring member or the third stirring member, a sufficiently large developer transport speed can be basically obtained. In addition, toner density unevenness in the axial direction of the developer supplied to the developer carrying member can be prevented, and sufficient charge rising characteristics of the toner can be reliably obtained. Problems such as scattering and fogging can be reduced or suppressed.

  The agitating member shown in FIG. 10 includes a first agitating unit configured by a plurality of semi-elliptical plate-like members provided in a first direction with respect to a plane perpendicular to the rotation axis J; The second stirrer configured with a plurality of semi-elliptical plate-like members provided in a slanted direction is a main element, and two plate-like members that are inclined in different directions are paired. It has the structure provided in the rotation-axis direction with the appropriate pitch p.

  The agitating member shown in FIG. 11 includes a first agitating portion configured by a plurality of semi-elliptical plate-like members provided in a first direction with respect to a plane perpendicular to the rotation axis J, and a second agitating member. And a second stirrer configured with a plurality of semi-elliptical plate-shaped members provided inclined in the direction of the outer side of the plate-shaped member constituting the first stirrer and the second stirrer It has a configuration in which plate-like ribs that extend continuously in the direction of the rotation axis are provided at four positions on the periphery that are equally spaced in the circumferential direction.

  An agitating member having a plate-like rib extending in the axial direction can be suitably used as, for example, a third agitating member. According to the developing device including the third agitating member having such a configuration, the operation and effect as described above. Can be obtained more reliably, and further reduction of toner scattering and fog due to poor charging of the toner can be expected, and image density due to non-uniformity of toner density with respect to the axial direction of the developer supplied to the developer carrier The occurrence of unevenness 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. 12 has toner recycling means (toner recycling apparatus) that collects toner removed from the photosensitive drum after transfer, and finally returns the toner to the developing apparatus for reuse.

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

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

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

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

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

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

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

  The 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 in the developer transport direction by the second stirring member 805 or the third stirring member. Thus, it is provided on the cover 812 corresponding to an appropriate position upstream of the toner supply port 813.

  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. 13, 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.

  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, and the third stirring member were produced.
(Rotating member A)
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 A 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 C)
The rotating member A has the same configuration as the rotating member A except that the spiral rib is clockwise.
(Rotating member E)
As shown in FIG. 8, 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 E 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 E modified)
In the rotating member E, the rotating member is configured such that the pitch (p) of the spiral rib is reduced from the upstream side to the downstream side in the developer conveying direction (upstream side: 36 mm → downstream side: 30 mm).
(Rotating member E modified 2)
Based on the rotating member E, a rotating member (upstream side: 0 mm (notch) having a radial length (synonymous with t, depth) of the notch is increased (synonymous with deep)) from the upstream side to the downstream side in the developer conveying direction None) → 5mm downstream
(Rotating member F)
The rotating member E has the same configuration as the rotating member E except that the pitch (p) of the spiral ribs is 20 mm.
(Rotating member F modified)
Based on the rotating member F, the rotating member is configured such that the radial length of the cutout is increased from the upstream side to the downstream side in the developer transport direction (0 mm upstream (no cutout) → 5 mm downstream)
(Rotating member F modified 2)
Based on the rotating member F, a rotating member having a circumferential length (U, synonymous with width) larger from the upstream side to the downstream side in the developer conveying direction is divided into three equal parts. From the side, 0 mm (no notch, 1 mm, 2 mm).
(Rotating member G)
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 G 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 H)
The rotating member G has the same configuration as the rotating member G except that the pitch (p) of the spiral ribs is 20 mm.
(Rotating member H modified)
Based on the rotating member H, a rotating member (having the same meaning as height, h, the same as the height) of the plate-shaped rib is increased from the upstream side toward the downstream side in the developer conveying direction (the stirring portion is divided into four equal parts, (2mm, 4mm, 6mm, 8mm from the upstream side).
(Rotating member H modified 2)
Based on the rotating member H, a rotating member (stirring portion is defined as having a larger length (synonymous with wide)) from the upstream side to the downstream side in the developer conveying direction from the upstream side in the developer conveying direction. Divided into four equal parts, 0mm from upstream (no plate-like ribs, 1mm, 2mm, 3mm).
(Rotating member I)
In the rotating member G, the length (W) in the axial direction of the plate-like ribs (vertical blades) is 12 mm, and plate-like ribs are provided at four positions per pitch (p) of the spiral ribs. A rotating member having the same configuration as the rotating member G.
(Rotating member J)
In the rotating member G, the length (W) in the axial direction of the plate-like ribs (vertical blades) is 20 mm, and plate-like ribs are provided at four positions per pitch (p) of the spiral ribs. A rotating member having the same configuration as the rotating member G.
(Rotating member K)
As shown in FIG. 9, 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 K are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis direction excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm, Radial length of plate-like rib (t): 3 mm, plate-like rib thickness: 1 mm, plate-like rib attachment location: two locations for shafts (rotating member K modified)
In the rotating member K, the rotating member is configured such that the pitch (p) of the spiral rib is reduced from the upstream side to the downstream side in the developer conveying direction (upstream side: 36 mm → downstream side: 30 mm).
(Rotating member K break 2)
Based on the rotating member K, a rotating member (stirring portion is defined as having a radial length (t, synonymous with height) is increased (synonymous with high) from the upstream side to the downstream side in the developer conveying direction. Divided into four equal parts, 0mm from upstream (no plate-like ribs, 1mm, 2mm, 3mm).
(Rotating member L)
A rotating member having the same configuration as the rotating member K except that the radial length (t) of the plate-like rib is 5 mm in the rotating member K.
(Rotating member L modified)
In the rotating member L, the rotating member is configured such that the pitch (p) of the spiral rib is reduced from the upstream side to the downstream side in the developer transport direction (upstream side: 36 mm → downstream side: 30 mm).
(Rotating member L modified 2)
Based on the rotating member L, the rotating member is configured such that the radial length (t, synonymous with height) of the plate-shaped rib is increased from the upstream side to the downstream side in the developer conveying direction (upstream side 1 mm → downstream side 5 mm). .
(Rotating member M)
In the rotating member K, the rotating member has the same configuration as the rotating member K except that four plate-like ribs are provided at equal intervals on the outer peripheral edge of the spiral rib.
(Rotating member M modified)
In the rotating member M, a rotating member in which the pitch (p) of the spiral rib is reduced from the upstream side to the downstream side in the developer conveying direction (upstream side: 36 mm → downstream side: 30 mm).
(Rotating member M modified 2)
Based on the rotating member M, the rotating member (the stirring portion is divided into four equal parts from the upstream side, and the radial length (t) of the plate-shaped rib is increased from the upstream side to the downstream side in the developer conveying direction. 0 mm (without plate-like ribs), 1 mm, 2 mm, 3 mm).
(Rotating member N)
The rotating member K has the same configuration as that of the rotating member K except that the spiral rib is clockwise.
(Rotating member O)
In the rotating member K, the rotating member has the same configuration as the rotating member K except that the spiral rib is clockwise and the radial length (t) of the plate-like rib is 5 mm.
(Rotating member O reform)
In the rotating member O, the rotating member is configured such that the pitch (p) of the spiral rib is reduced from the upstream side to the downstream side in the developer conveying direction (upstream side: 36 mm → downstream side: 30 mm).
(Rotating member O reform 2)
A rotating member in which the radial length of the plate-shaped rib is increased from the upstream side to the downstream side in the developer transport direction based on the rotating member O (upstream side 1 mm → downstream side 5 mm).
(Rotating member P)
In the rotating member K, the rotating member has the same configuration as the rotating member K except that the spiral rib is wound clockwise and the plate-like ribs are attached at four equally spaced locations in the circumferential direction.
(Rotating member P modified)
In the rotating member P, the rotating member is configured such that the pitch (p) of the spiral rib is decreased from the upstream side to the downstream side in the developer transport direction (upstream side: 36 mm → downstream side: 30 mm).
(Rotating member P break 2)
Based on the rotating member P, the rotating member (the stirring portion is divided into four equal parts from the upstream side, with the radial length (t) of the plate-shaped rib being increased from the upstream side to the downstream side in the developer conveying direction. 0 mm (without plate-like ribs), 1 mm, 2 mm, 3 mm).
(Rotating member U)
As shown in FIG. 10, a first stirring unit and a second stirring unit configured by a plurality of semi-elliptical plate-like members provided 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 U 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 V)
As shown in FIG. 11, the first stirring unit and the second stirring unit configured with a plurality of semi-elliptical plate-like members provided 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 rotating member having a structure in which a disc-shaped flange member having an outer dimension of 24 mm is provided at both ends of the rotating member.

  The specifications of the rotating member V 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 pitch (p): 25 mm, plate-like rib Radial length (t): 3 mm, plate-like rib thickness: 1 mm
(Rotating member W)
As shown in FIG. 10, a first stirring unit and a second stirring unit configured with a plurality of semi-elliptical plate-like members provided to be inclined in different directions with respect to a plane perpendicular to the shaft member. And a rotary member having a disk-like flange member having an outer dimension of 24 mm at both ends of the rotary member.

  The specifications of the rotating member W 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 X)
As shown in FIG. 11, the first stirring unit and the second stirring unit configured with a plurality of semi-elliptical plate-like members provided 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 rotating member having a structure in which a disc-shaped flange member having an outer dimension of 24 mm is provided at both ends of the rotating member.

  The specifications of the rotating member X 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
(Other stirring members)
<Experimental example 1>
[Create developer]
In accordance with the configuration shown in FIGS. 2 to 4, developing devices 1 to 14 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. The comparative developing device 9 with the reverse direction and the comparative developing devices 15 to 26 having no third stirring member were produced.

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

  The toner supply ports in the developing devices 1 to 8 and the comparative developing device 9 according to the present invention are formed at positions where the second stirring member and the third stirring material face each other (perpendicular to the longitudinal direction). When viewed in cross section, it is the upper position in the middle of both members, and is a position 15 mm downstream from the upstream edge in the developer transport direction by the second stirring member or the third stirring member.

  In addition, the toner supply port forming position in each of the developing devices 10 to 19 for comparison is an upper position on the rear side (the side far from the developer carrier) of the second stirring member, and the second stirring member Is a position 15 mm downstream from the upstream edge in the developer conveyance direction.

  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 filling amount is 1200 g for the developing devices 1 to 145 and 800 g for 15 to 26.

  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 of the polymerized toner having an average of 18 ± 2%, the large particle size silica 0.8% by mass, the small particle size silica 0.2% by mass, the large particle size titania 0.2% by mass, and the 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 14 and the comparative developing devices 15 to 26 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.

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

  The “moving direction in the second / third facing portion” indicates the moving direction of the circumferential surfaces of the two stirring members when viewed in the proximity of the second stirring member and the third stirring member.

  Further, for example, two types of rotation speeds of the stirring members in the developing devices 19 to 25 are displayed. 400 rpm is the rotation speed in color image formation, and 650 rpm is the rotation speed used in monochrome image formation, which will be described later. Related to Tables 2 and 3.

  The developing device for comparison 26 has a spiral rib having a notch as the first stirring member and a spiral rib having the second stirring member so that the developer transport amount is different. However, in this configuration, the developer stagnated and biased on the downstream side of the second agitating member, resulting in a packing state, and thus the amount of developer movement was not measured.

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

The image forming conditions were set to be the same for all of the image forming units related to the respective color toner images.
<Image forming conditions>
-Process speed (V): 220 mm / sec (number of images formed per minute is 50)
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 character / line pattern, the presence / absence of character scattering, the density of 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) single color characters / line + halftone (10 steps) pattern (printing rate 30%) are output in succession 50 sheets.
(2) Cyan (C) single color solid pattern (printing rate 80%) is output continuously 150 sheets.
(3) Cyan (C) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets.
(4) Blue (magenta (M) + cyan (C)) single-color character / line + halftone (10 steps) pattern (printing rate of 30% for both M and C) is output in 50 sheets.
(5) Continuous output of 150 solid blue solid patterns (printing rate of 80% for both M and C).
(6) Output 50 sheets of blue (magenta (M) + cyan (C)) single color characters / line patterns (printing rate 7% for both M and C) continuously.

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

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

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

  When no in-machine 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.

  Further, in the developing device 26 for comparison, since the developer is biased and stayed, image output is not performed.

<Experimental example 2>
[Production of development device]
In each of the developing devices 1 to 5, 8 to 12, and 16 to 26 used in Experimental Example 1, the recycled toner supply port is positioned 8 mm upstream from the toner supply port in the developer transport direction by the second stirring member. 1 to 5, 8 to 12 and 16 to 26 were produced (developing device numbers in all tables are unified for easy understanding of correspondence).

  In the configuration shown in FIG. 12, an image forming apparatus for forming a monochrome image having toner recycling means mounted on each of the developing devices 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 sheets), and for the developing devices 1 to 12, the first stirring member, the second stirring member, and the third stirring member Is set to 400 rpm, the rotation speed is 400 rpm for the first and second stirring members in the developing devices 16 to 18 that do not have the third stirring member, and the rotation speed is 650 rpm for the developing devices 13 to 26. .

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

The results are shown in Table 3 below.
(7) Black (BK) single color characters / lines + halftone (10 steps) pattern (print rate 30%) are output in succession 50 sheets.
(8) Continuously output 150 black (BK) solid patterns (printing rate 80%).
(9) Black (BK) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets.
<Evaluation criteria>
The image density unevenness is measured by measuring the relative reflection density at any nine locations in the black (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 for the developing device 26 for comparison, since the developer is biased and stayed, image output is not performed.

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

  In addition, the occurrence of image defects such as image fogging, character scattering, and image density unevenness can be suppressed, and the occurrence of in-machine contamination due to toner scattering can be reduced, and a high-quality image can be formed.

  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. The BB sectional drawing in FIG. 2 is shown. It is a schematic diagram which shows the 1st example of a stirring member. In particular, it is a schematic diagram for explaining the positional relationship between the developer carrier and the first 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.

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

Claims (12)

A developer carrier having a magnetic field generating means fixedly disposed therein and carrying a developer including toner and carrier;
A first stirring member provided adjacent to the rotation axis direction of the developer carrier;
The first stirring member to transport the developer in a direction farther from the first stirring member relative to the developer carrying member and in a direction opposite to the developer transport direction by the first stirring member. A second stirring member provided adjacent to the rotation axis direction of
A housing that rotatably supports and accommodates the developer carrier, the first stirring member, and the second stirring member, and has a partition wall between the first stirring member and the second stirring member When,
In the developer circulating type developing device having a cover provided on the upper part of the housing,
The developer conveying capability of the second stirring member is set lower than the developer conveying capability of the first stirring member, and
A third stirring member having a developer conveying ability substantially the same as or lower than that of the second stirring member is provided to be rotatable in opposition to the second stirring member;
The total developer transport amount in the rotation axis direction of the second stirring member and the third stirring member is reduced from the upstream side to the downstream side when viewed in the developer transport direction by the two stirring members. Set and also
The developer transport amount in the rotation axis direction by the first stirring member is set to be substantially the same as the total developer transport amount on the downstream side of the developer by the second and third stirring members,
The second agitating member and the third agitating member are viewed at their opposing proximity points so that the peripheral surface moves downward from above,
When the second stirring member and the third stirring member are viewed from the side, the second stirring member and the third stirring member include a substantially intermediate portion between them, and correspond to an upstream position when viewed in the developer transport direction by the second stirring member. A toner supply port for supplying toner is provided in an area on the cover.
A developing device. At least one of the second stirring member or the third stirring member is constituted by a spiral rib formed around the rotation axis, and the pitch of the spiral rib is determined by the developer transport direction by the two stirring members. The developing device according to claim 1, wherein the developing device is set to be smaller from the upstream side toward the downstream side. At least one of the second stirring member or the third stirring member is composed of a spiral rib formed around the rotation axis and a rod-like or plate-like rib provided between the spiral ribs,
The height or width of the rod-shaped or plate-shaped rib is set to be higher or wider from the upstream side to the downstream side when viewed in the developer transport direction of the two stirring members. 2. The developing device according to 1. At least one of the second stirring member or the third stirring member is formed of a spiral rib having a notch formed around a rotation axis, and the depth or width of the notch is set to the both The developing device according to claim 1, wherein the developing device is set to be deeper or wider from the upstream side toward the downstream side when viewed in the developer conveying direction by the stirring member. At least one of the second stirring member or the third stirring member includes a spiral rib formed around the rotation axis, and a plate-like rib extending in the rotation axis direction so as to cross the spiral rib. Configure
2. The developing device according to claim 1, wherein the width of the plate-like rib is set wider from the upstream side toward the downstream side when viewed in the developer conveying direction of the two stirring members. A plurality of plate-like members provided around the rotation axis and inclined in the first direction with respect to the rotation axis, and a plurality of plate-like members provided inclined in the second direction 6. The developing device according to claim 1, wherein the developing device comprises a member. The peripheral surface of the developer carrying member and the first stirring member move in directions opposite to each other at an opposing proximity point thereof. Development device. The magnetic field generating means has adjacent repulsive magnetic poles of the same polarity,
The developing device according to claim 1, wherein an opposing proximity point between the developer carrying member and the first stirring member is substantially between the repulsive magnetic poles. When the volume average particle diameter of the toner is Dt [μm] and the volume average particle diameter of the carrier is Dc [μm],
Dt = 3-5
Dc = 5 · Dt ~ 10 · Dt
The developing device according to claim 1, wherein a developer containing the toner and carrier is used. An image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image into a toner image.
While using the developing device according to any one of claims 1 to 9, as the developing 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]. When
W ≧ M ・ V ・ L / 1000
R ≦ 600
An image forming apparatus. An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier 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
While using the developing device of any one of Claim 1 thru | or 9 as said image development means,
Recycled toner is disposed on the cover of the developing device at a position corresponding to the space between the second stirring member and the third stirring member and corresponding to the upstream side when viewed in the developer transport direction by the two stirring members. An image forming apparatus provided with a recycled toner supply port for supply. 12. The image forming apparatus according to claim 11, wherein the recycled toner supply port is located upstream of the toner supply port as viewed in the developer conveying direction of both stirring members.

Images