JP2006072076A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device and an image forming apparatus having a new configuration which have simple constitution and yet can impart a predetermined charge amount to toner without decreasing the transport speed of a developer, and which can form an image of high image quality. <P>SOLUTION: The developing device has: constitution of circulating and transporting a developer by a developer supplying and recovering member and by a first stirring member; and constitution of allowing the toner supplied to the opposing portions of first and second stirring members through a toner supply port formed on the cover of a housing to submerge into the developer through rotation of the first and second stirring members which rotate in such a manner that respective circumferential faces move downward from an upper side. The image forming apparatus is equipped with the developing device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

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

  In addition, a developer carrying member made of a rotatable cylindrical member, a position-fixed magnet built in the developer carrying member, and a two-component developer are agitated to give a charge amount necessary for development processing. The developing device is configured with the stirring member as a main element, and during the development processing, the stirred two-component developer adsorbed by the action of the magnet is carried on the peripheral surface of the developer carrying member, and the developer carrying member Also known is a developing device having a configuration in which the developer is sequentially conveyed to the developing region by the rotation, and the developer after the development is automatically removed from the developer carrying member using a repulsive magnetic field.

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

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

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

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

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

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

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

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

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

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

The object of the present invention can be achieved by the following constitution.
(Claim 1)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer agitating section that is adjacent to the longitudinal direction of the developer supply / recovery member and can transport substantially the same amount of developer in the opposite direction to the developer transport direction by the developer supply / recovery member. A first stirring member provided in
A second agitating member adjacent to the longitudinal direction of the first agitating member on the side farther from the first agitating member with respect to the developer carrying member, and having no developer conveying ability in the rotation axis direction; A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the outer diameter of the second stirring member larger than the outer diameter of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device.
(Claim 2)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer agitating section that is adjacent to the longitudinal direction of the developer supply / recovery member and can transport substantially the same amount of developer in the opposite direction to the developer transport direction by the developer supply / recovery member. A first stirring member provided in
A second agitating member adjacent to the longitudinal direction of the first agitating member on the side farther from the first agitating member with respect to the developer carrying member, and having no developer conveying ability in the rotation axis direction; A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
The rotational speed of the second stirring member is set to be higher than the rotational speed of the first stirring member, and the peripheral surface is determined by viewing the first stirring member and the second stirring member at their opposing proximity points. It can move from top to bottom, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device.
(Claim 3)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer agitating section that is adjacent to the longitudinal direction of the developer supply / recovery member and can transport substantially the same amount of developer in the opposite direction to the developer transport direction by the developer supply / recovery member. A first stirring member provided in
A second agitating member adjacent to the longitudinal direction of the first agitating member on the side farther from the first agitating member with respect to the developer carrying member, and having no developer conveying ability in the rotation axis direction; A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the peripheral speed of the second stirring member higher than the peripheral speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device.
(Claim 4)
The second stirring member includes a plurality of plate-like members provided around the rotation axis and inclined in the same direction with respect to the rotation axis. 2. The developing device according to item 1.
(Claim 5)
The said 2nd stirring member has a plate-shaped rib provided in the said rotating shaft direction around the rotating shaft or the said rotating shaft with the clearance gap, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The developing device according to item.
(Claim 6)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
Adjacent to the longitudinal direction of the developer supply / recovery member, and having a developer transport capability lower than the developer transport capability of the developer supply / recovery member, the developer transport direction of the developer supply / recovery member A first stirring member provided in the developer stirring unit that transports the developer in the opposite direction;
Whether the developer carrier is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and the developer conveying capability in the rotation axis direction is substantially the same as that of the first stirring member. Or a second stirring member that has a developer transport capability lower than that of the first stirring member and transports the developer in the same direction as the developer transport direction of the first stirring member;
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the outer diameter of the second stirring member larger than the outer diameter of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device.
(Claim 7)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
Adjacent to the longitudinal direction of the developer supply / recovery member, and having a developer transport capability lower than the developer transport capability of the developer supply / recovery member, the developer transport direction of the developer supply / recovery member A first stirring member provided in the developer stirring unit that transports the developer in the opposite direction;
Whether the developer carrier is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and the developer conveying capability in the rotation axis direction is substantially the same as that of the first stirring member. Or a second stirring member that has a developer transport capability lower than that of the first stirring member and transports the developer in the same direction as the developer transport direction of the first stirring member;
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
The rotational speed of the second stirring member is set to be higher than the rotational speed of the first stirring member, and the peripheral surface is determined by viewing the first stirring member and the second stirring member at their opposing proximity points. It can move from top to bottom, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device.
(Claim 8)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
Adjacent to the longitudinal direction of the developer supply / recovery member, and having a developer transport capability lower than the developer transport capability of the developer supply / recovery member, the developer transport direction of the developer supply / recovery member A first stirring member provided in the developer stirring unit that transports the developer in the opposite direction;
Whether the developer carrier is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and the developer conveying capability in the rotation axis direction is substantially the same as that of the first stirring member. Or a second stirring member that has a developer transport capability lower than that of the first stirring member and transports the developer in the same direction as the developer transport direction of the first stirring member;
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the peripheral speed of the second stirring member higher than the peripheral speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device.
(Claim 9)
The second stirring member is provided around the rotation axis and a plurality of first plate-like members provided to be inclined in the first direction with respect to the rotation axis, and to be inclined in the second direction. The developing device according to claim 6, further comprising: a second plate-like member.
(Claim 10)
The said 2nd stirring member has a plate-shaped rib provided in the said rotating shaft direction around the rotating shaft or with the rotating shaft and the clearance gap, The any one of Claim 6 thru | or 9 characterized by the above-mentioned. The developing device according to item.
(Claim 11)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer adjacent to the longitudinal direction of the developer supply / recovery member and in the same direction as the transport direction of the developer supply / recovery member with a developer transport capability lower than the developer transport capability of the developer supply / recovery member. A first stirring member provided in the developer stirring unit,
The developer carrying member is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and has a higher developer transport capability in the rotation axis direction than the developer supply and recovery member. And a second stirring member that conveys the developer in a direction opposite to the developer supply and recovery member,
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the outer diameter of the second stirring member larger than the outer diameter of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the first stirring member and the second stirring member facing each other, as viewed in the developer transport direction by the second stirring member With a mouth,
A developing device.
(Claim 12)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer adjacent to the longitudinal direction of the developer supply / recovery member and in the same direction as the transport direction of the developer supply / recovery member with a developer transport capability lower than the developer transport capability of the developer supply / recovery member. A first stirring member provided in the developer stirring unit,
The developer carrying member is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and has a higher developer transport capability in the rotation axis direction than the developer supply and recovery member. And a second stirring member that conveys the developer in a direction opposite to the developer supply and recovery member,
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the rotation speed of the second stirring member higher than the rotation speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the first stirring member and the second stirring member facing each other, as viewed in the developer transport direction by the second stirring member With a mouth,
A developing device.
(Claim 13)
A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer adjacent to the longitudinal direction of the developer supply / recovery member and in the same direction as the transport direction of the developer supply / recovery member with a developer transport capability lower than the developer transport capability of the developer supply / recovery member. A first stirring member provided in the developer stirring unit,
The developer carrying member is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and has a higher developer transport capability in the rotation axis direction than the developer supply and recovery member. And a second stirring member that conveys the developer in a direction opposite to the developer supply and recovery member,
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the peripheral speed of the second stirring member higher than the peripheral speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the first stirring member and the second stirring member facing each other, as viewed in the developer transport direction by the second stirring member With a mouth,
A developing device.
(Claim 14)
The first agitating member is provided around the rotating shaft and inclined in the second direction with a plurality of first plate members provided inclined with respect to the rotating shaft in the first direction. The developing device according to claim 11, further comprising: a second plate member.
(Claim 15)
The said 2nd stirring member has a plate-shaped rib provided in the said rotating shaft direction around the rotating shaft or with the rotating shaft and the clearance gap, The any one of Claim 11 thru | or 14 characterized by the above-mentioned. The developing device according to item.
(Claim 16)
16. The developer carrier according to claim 1, wherein the developer carrying member and the developer supply / recovery member move in opposite directions when viewed from their opposing proximity points. Development device.
(Claim 17)
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 claims 1 to 16, wherein a developer including a toner and a carrier is used.
(Claim 18)
An image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image into a toner image.
While using the developing device of any one of Claim 1 thru | or 17 as said image development means,
The moving speed of the image carrier is V [mm / sec], the maximum adhesion amount per unit area of the toner image formed on the image carrier is M [mg / cm ² ], and the direction orthogonal to the moving direction of the image carrier The maximum width of the toner image is L [mm], the developer movement amount in the rotation axis direction of the developer carrier by the developer supply / recovery member is Wo [g / sec], and the rotation speed of the developer supply / recovery member is R [ rpm] when Wo ≧ M · V · L / 1000
R ≦ 600
An image forming apparatus.
(Claim 19)
An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier Transfer means for transferring an image to a transfer material or intermediate transfer member, cleaning means for cleaning the surface of the image carrier after transfer, and toner removed from the surface of the image carrier by the cleaning means are supplied to the developing means. In an image forming apparatus having toner recycling means for recycling
The developing device according to any one of claims 1 to 17 is used as the developing unit, and the developing device is on a cover of the developing device and corresponds between the first stirring member and the second stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner at a position.
(Claim 20)
20. The image forming apparatus according to claim 19, wherein the recycled toner supply port is located upstream of the toner supply port in the overall developer movement direction (circulation movement direction) in the developer stirring section. apparatus.

  According to the developing device of the present invention, for example, the developer supply / recovery member installed in the developer supply / recovery unit provided in the developing device, and the stirring member (first stirring member or The developer is circulated and conveyed in the direction of the rotation axis of the developer carrier while stirring the developer with the first agitating member and the second agitating member) to balance the developer conveying speed or conveying amount. The second agitating member agitates the developer in the circumferential direction without substantially conveying it in the direction of the rotation axis, and sufficiently increases the developer conveyance speed without increasing the toner charge in the developer. A sufficient agitation time can be ensured.

  Since the developer can be supplied to the developer carrier in a state where the toner in the developer has a desired charge amount, fog and toner scattering due to poor charging of the toner can be prevented. It can be suppressed, and even a color image can maintain high image quality.

  Also, a second stirring member is provided opposite to the longitudinal direction of the first stirring member, and both the stirring members are viewed at their opposing proximity points so that each peripheral surface moves in a forward direction from the upper side to the lower side. In addition, since the toner is replenished from above corresponding to the opposite portions, the sinking of the replenished toner into the developer can be accelerated.

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

  Further, by setting the outer diameter, rotation speed, and peripheral speed of the second stirring member larger or higher than the outer diameter, rotation speed, and peripheral speed of the first stirring member, the developer stirring performance is improved as a result. Can be made.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  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 image forming unit 30 has one plane (stretched surface) of a loop-shaped rotating belt (hereinafter referred to as an intermediate transfer belt) 401 that constitutes the belt unit 4 and is long disposed in the belt installation portion. A, A, A, Magenta, cyan, and black are arranged in this order along A.

  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 a suitable timing corresponding to image formation on the intermediate transfer belt 401, the selected paper P is fed by the paper feed rollers 503 (513, 523) positioned in the feed sections 501 (511, 521) of the paper feed section 5. The paper is transported 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.

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

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

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

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

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

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

  In the drawing, 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 discharged paper 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 of the discharge forms described above is selected for the discharge after being sent out from the fixing device T.

  Next, a first embodiment of a developing device which is a toner image forming unit (developing unit) will be described with reference to FIGS.

  In this specification, the left-right direction in FIG. 2 is referred to as the “front-rear direction” with reference to the developer carrier, and the up-down direction in FIG. Further, the vertical direction in FIGS. 3 and 4 is expressed as “vertical direction”.

  The developing device 8 includes a developer carrier (developing sleeve) 800, a developer supply / recovery member 803 rotatably disposed at a position adjacent to the longitudinal direction of the developer carrier 800, and the developer supply / recovery. A first agitating member 805 disposed rotatably at a position adjacent to the longitudinal direction of the member 803 (rear side), and a rotatably disposed at a position adjacent to the longitudinal direction of the first agitating member (rear side). It has a second stirring member 807, a housing 810 that supports these members in an axial direction while keeping them parallel to each other in the axial direction, and an openable / closable cover 812 that covers the top of the housing.

  The developer supply / recovery member 803, the first stirring member 805, and the second stirring member 807 are configured to be longer than the length of the developer carrier 800.

  Then, by positioning one end position of these members in substantially the same plane as the end position of the developer carrier, the housing 810 together with the end of the developer carrier 800 on the other side. It is protruding.

  In other words, as shown by the arrows in FIG. 2, the developer supply and recovery member 803 extends and projects downstream in the developer transport direction. Reference numeral 802 indicates a protruding region.

  Further, as shown in FIGS. 3 and 4, the rotation shaft of the stirring member including the developer supply / recovery member is configured to be positioned on substantially the same horizontal plane.

  The developer carrying member 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 therein in a fixed position.

  Reference numeral 808 denotes a partition wall formed by rising from the bottom of the housing 810, which is located between the developer supply / recovery member 803 and the first stirring member 805, and the portions at both ends thereof are missing and are used for developer circulation. The passages 820 and 821 are formed.

  The portions of the developer supply / recovery member 803 and the first agitating member 805 corresponding to the passages 820 and 821 corresponding to the downstream side when viewed in the developer transport direction (indicated by arrows) It is preferable to make it an impeller shape so that it can be performed smoothly.

  The impeller shape can be obtained by fixing a plurality of flat plates (blades) at equal intervals (equal angles) on the rotation shaft circumferential surface.

  As shown in FIG. 3, the developer carrier 800 and the developer supply / recovery member 803 are partitioned by the partition wall 808, and a developer supply / recovery unit (hereinafter referred to as the first supply unit) formed in the housing 810. The first agitating member 805 and the second agitating member 807 are accommodated in a second agitating portion 816 formed adjacent to the first agitating portion 815. Has been.

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

  The developer supply / recovery member 803 and the first agitating member 805 are preferably constituted by a rotating member having a high developer carrying capability in the rotation axis direction from the viewpoint of preventing occurrence of uneven toner density in the rotation axis direction. .

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

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

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

  Referring to the developer transport direction, the developer supply / recovery member 803 rotates by transporting the developer in a first direction (in the drawing, the rotation axis direction from the upper side to the lower side), and the first stirring member 805. The developer is transported in the direction opposite to the transport direction by the developer supply / recovery member 803 (in the drawing, the rotational axis direction from the lower side to the upper side).

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

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

  As for the developer carrying capacity, the developer supply / recovery member 803 and the first stirring member 805 have substantially the same carrying ability, and the second stirring member 807 does not have a substantial carrying ability as described above.

  Here, the “stirring member that does not have a substantial conveyance capability or has substantially no conveyance capability” refers to a stirring member that does not take a form of positively conveying the developer in the direction of the rotation axis. .

  The carrying capacity of the developer supply / recovery member and the 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 stirred in the circumferential direction of the rotation shaft J in the axial direction indicated by the arrow by the rotation of the developer supply / recovery member 803. In addition, it is fed into the second storage and agitation unit 816 via the passage 821.

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

  The developer that receives the action of the second agitating member 807 is agitated in the circumferential direction of the rotation axis J, and the rising of the charge is promoted. At the same time, the developer is subjected to the action of the first agitating member 805.

  Note that the developer containing toner that has reached a predetermined charge amount by the mixing / stirring action during the circulating conveyance is conveyed on the peripheral surface of the developer carrier 800 while being conveyed by the developer supply / recovery member 803. The toner is supplied in the axial direction and subjected to development processing, and the toner in the developer is consumed for visualization.

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

  At this time, the developer supply / recovery member 803 and the developer carrier 800 are rotated in the opposite direction (axis) at the closest point, and the removed toner is not immediately supplied to the developer carrier 800. The developer supply / recovery member 803 receives the transport action and is taken into the circulation flow path, and the desired charge amount is obtained again while being transported through the circulation transport path and used for the development process. Become.

  In other words, by changing the rotation direction of the developer carrier 800 and the developer supply / recovery member 803 as described above, the developer supplied to the developer carrier 800 and the recovered developer can be reliably exchanged. Therefore, since the toner density of the developer in the axial direction of the developer carrier 800 can be kept uniform, the occurrence of image density unevenness can be reduced.

  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 first stirring member 805 and the second stirring member 807 face each other (as shown in the side sectional view of FIG. 4, the first stirring member 805 and the second stirring member 807). Corresponds to an appropriate position on the upstream side (for example, in the region of about 40 mm to 50 mm from the upstream end) in the developer transport direction by the first stirring member. Is provided on the cover 812.

  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 as the upstream position as described above is intended to achieve effective mixing and stirring even when the axial length of the second stirring member 807 is short.

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

  That is, the first agitating member 805 and the second agitating member 807 are rotated so that the peripheral surface moves from the upper side to the lower side when viewed from the opposing proximity point of the first agitating member 805 and the second agitating member 807 (eg When attention is paid to one point on the peripheral surface, it means that the one point reaches the proximity point from above with respect to the proximity point, and rotates around the axis so as to come out downward). The toner can be quickly submerged in, and the toner can be quickly and uniformly dispersed in the developer.

  As described above, by making the developer supply / recovery member 803 and the first agitating member 805 substantially equal to each other, it is possible to suppress the occurrence of developer stagnation on the circulation conveyance path and to smoothly circulate the developer. Can be done.

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

  Furthermore, since sufficient stirring can be performed in the circumferential direction of the stirring member, for example, a developer having a uniform toner concentration in the axial direction of the first stirring member can be easily obtained in a short time. .

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

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

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

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

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

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

  When the developer movement amount (developer transport amount) Wo in the rotation axis direction by the developer supply / recovery member 803 is excessively small (for example, 150 rpm), development on the downstream side in the developer transport direction of the developer supply / recovery member 803 is performed. The toner concentration in the developer is lowered in the agent supply region, and it becomes difficult to supply a sufficient amount of toner to the development region, and image density unevenness is likely to occur.

  Further, when the rotation speed of the developer supply / recovery member 803 is excessive (the rotation speed exceeding 600 rpm, for example, 650 rpm), the developer is caused by heat generated at the shaft portion of the developer supply / recovery member 803. It becomes easy to deteriorate and it becomes difficult to form a high-quality image over a long period of time.

  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 region in the axial direction without toner density unevenness. Therefore, an image having a uniform image density without image density unevenness can be obtained.

  Moreover, by setting the rotation speed of the developer supply / recovery member to 600 rpm or less, it is possible to prevent the developer from being deteriorated by heat generated when the developer supply / recovery member is rotated at a high speed.

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

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

  In the developing device having the above-described configuration, at least one of the outer diameter, the rotational speed, the peripheral speed, and the virtual cross-sectional area of the first stirring member is set to the outer diameter, the rotational speed, the peripheral speed, and the virtual section of the second stirring member. By setting the area larger or higher than the area, the stirring performance can be improved as compared with the case where the same setting is applied.

  In this case, for example, only the outer diameter may be changed, but a plurality of factors such as the outer diameter and the rotational speed may be used in combination.

  The virtual cross-sectional area referred to here is the state in which the rotation axis is subtracted from the diameter of the virtual circle caused by the (maximum) outer diameter of the stirring member in a state where the rotation axis is viewed from the direction orthogonal to the longitudinal direction. Refers to the donut-shaped cross-sectional area.

  As described above, one embodiment of the developing device and the image forming apparatus according to the present invention has been described. However, the developer supply / recovery member, the first stirring member, and the second stirring member in the developing device are all limited to those having the above-described configuration. Is not to be done.

  For example, a rotating member having the configuration schematically shown in FIGS. 7 to 10 can be used as the developer supply / recovery member or the first stirring member.

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

  Here, the term “rotating member” basically indicates a member having an appropriate configuration that can be used as the developer supply / recovery member, the first stirring member, or the second stirring member before being incorporated in the developing device, and is incorporated in the developing device. The rotating member after that is called a developer supply / recovery member, a first stirring member, and a second stirring member depending on the installation location.

  The rotating member shown in FIGS. 7 to 10 has the same basic configuration as the rotating member shown in FIG. 5, but has a further increased developer stirring ability, and causes toner density unevenness in the axial direction. It has sufficient developer transport capability that is required to prevent this.

  The rotating member shown in FIG. 7 is on the outer periphery of the rotating shaft J and on the outer periphery of the rotating shaft J, and the helical rib 850 formed at a pitch p of 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 of the spiral ribs 850, and are provided in a line (linear shape) in the direction of the rotation axis.

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

  The rotating member shown in FIG. 8 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 of a predetermined size in the axial direction. Rod-like or plate-like ribs (vertical blades) 856 provided in a row in the direction of the rotation axis, and the ribs 856 are configured in a plurality of rows.

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

  The length (meaning width) W of the rib 856 in the rotation axis direction is configured to be larger than the width W of the rib 855 shown in FIG. 7, but the size, the number of rows, etc. of the width W are intended. Anything can be achieved, and the degree of freedom in design is wide. Note that h represents a length in the radial direction (meaning height).

  The rotating member shown in FIG. 9 includes a spiral rib 850 that is formed on the entire outer peripheral surface of the rotating shaft J and has a pitch p having a predetermined size in the axial direction. Has a notch 857 penetrating 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 figure, U indicates the length (meaning width) of the notch in the circumferential direction, and t indicates the radial length (depth) of the notch.

  The rotating member shown in FIG. 10 is rotated through the spiral rib 850 formed over the entire outer peripheral surface of the rotating shaft J and at a predetermined pitch p in the axial direction, and the outer peripheral edge of the spiral rib. And plate-like ribs 858 extending linearly in the direction of the axis J.

  In this example, plate-like ribs 858 are provided at two locations (upper edge portion and lower edge portion in the figure) that are axial objects.

  According to the developing device provided with these rotating members, basically, a sufficiently large developer conveying speed can be obtained, and the toner concentration with respect to the axial direction of the developer supplied to the developer carrying member can be obtained. The occurrence of unevenness can be prevented, and sufficient charge rising characteristics of the toner can be reliably obtained, so that problems such as toner scattering and fogging due to poor charging can be reduced and suppressed.

  FIGS. 11 to 13 show other configuration examples of the rotating member that can be used as the second stirring member, and FIGS. 14 and 15 are used as the second stirring member in the developing device of the embodiment described later. The structural example of the rotation member which can be shown is shown.

  The rotating member shown in FIG. 11 has a configuration in which plate-like ribs 860 are formed linearly along the axial direction on the outer peripheral surface of the rotating shaft J.

  The rotating member having the illustrated configuration has a cross paddle shape (an example of the above-described impeller shape) in which plate-like ribs 860 are provided at four locations equally dividing the circumferential direction of the rotation axis J.

  The rotating member shown in FIG. 12 is provided at equal intervals in the circumferential direction, supporting the plate-like member through engagement between a plurality of plate-like members 851 having an elliptical shape and the peripheral edge of the plate-like member 851. From four plate-like ribs 858, disk-like flanges F provided at both ends so as to engage and hold the end portions of the plate-like ribs 858, and from the center of the flange F A rotating shaft (not shown) extending outward is a main element. The plate-like rib 858 has a configuration that extends without a break in the direction of the rotation axis.

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

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

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

  The rotating members shown in FIG. 13 are arranged at equal intervals in the circumferential direction of the flange F, with two disk-shaped flanges F that each engage with the end of the rotating shaft J and hold the rotating shaft. Supported by four plate-like ribs 858 and plate-like ribs 858 extending linearly in the direction of the rotation axis J in a state where the rotation axis J passes along a plane perpendicular to the rotation axis J. A plurality of plate-like members 851 are the main elements.

  The plate-like member 851 is a disc having a notch portion 854 having a predetermined size except for a predetermined region in the central portion that fits with the rotation shaft, and the outer diameter end of the center of the plate-like member and the notch portion. The remaining angle of the notch angle formed by connecting the two is the mounting angle of the plate member.

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

  The rotating member shown in FIG. 14 includes a first stirring portion made up of a plurality of plate-like members 870 provided on the rotation axis J and inclined in the first direction, and a plurality provided inclined in the second direction. And a second stirring portion made of a plate-shaped member 871.

  More specifically, for example, the plate-like members 870 and 871 made of semi-elliptical plates are inclined in directions different from each other with respect to the same plane perpendicular to the rotation axis and on the same plane perpendicular to the rotation axis. And a plurality of such sets are arranged in the axial direction at a predetermined pitch p.

  F indicates a flange.

  The basic structure of the rotating member shown in FIG. 15 is the same as that of FIG. 14, and is inclined on the outer peripheral surface of the rotating shaft J in the first direction with respect to the same plane perpendicular to the rotating shaft. A plurality of pairs of a plate-like member 870 made of a semi-elliptical plate provided and a plate-like member 871 made of a semi-elliptical plate provided to be inclined in the second direction are arranged in the axial direction at a predetermined pitch p. In addition, the plate-like members 870 and 871 are provided with plate-like ribs 858 extending linearly in the direction of the rotation axis J.

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

  11 to 15, the size of the area of the plate-shaped member that contacts the developer, the pitch p, the size of the area of the plate-shaped rib 858 that contacts the developer, the number of plate-shaped ribs, etc. are subject to the conditions. It can be determined accordingly.

  Further, according to the developing device using the rotating member having such a configuration as the second stirring member, it is easy to impart charge to the toner, and further reduction of toner scattering and fogging due to toner charging failure can be expected. Further, the occurrence of uneven image density due to non-uniformity of the toner density in the axial direction of the developer supplied to the developer carrying member 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.

  In the first embodiment of the developing device, the second stirring member does not have the developer conveying ability in the rotation axis direction. However, the second and third embodiments shown in FIGS. 16 and 17 are used. As in the embodiment, the second stirring member can be provided with a developer conveying ability.

  In this case, as the second stirring member, a rotating member in a form that can be used as the developer supply / recovery member or the first stirring member is used.

  The difference in configuration between the developing device according to the first embodiment and the developing device according to the second embodiment shown in FIG. 16 is that the second agitating member 807 has a developer conveying capability. In other words, the developer conveying capability of the first agitating member 805 is reduced, and other configurations are not changed.

  In other words, substantially the same amount of developer as the developer supply / recovery member 803 is shared by the first and second agitating members 805 and 807, and the developer is smoothly circulated. It has the structure which performs.

  As is apparent from the figure, for example, the developer conveying ability of each of the first and second stirring members 805 is set to half of the developer conveying ability in the rotation axis direction of the developer supply / recovery member 803, and By setting the transport direction of the developer by the two agitating members to be opposite to the transport direction of the developer by the developer supply and recovery member, a good charge amount can be obtained without causing a decrease in the developer transport speed. Since the toner can be applied to the toner, and the new toner can be quickly dispersed in the developer, the same effects as those described in the first embodiment can be obtained.

  In the developing device having the configuration shown in FIG. 17, the developer conveying capability of the first stirring member 805 is set lower than that of the developer supply / recovery member, and the developer conveyance direction is set to the conveyance direction by the developer supply / recovery member. On the other hand, the developer conveying capability by the second agitating member 807 is set to be substantially the same as the developer conveying capability by the both, and the developer conveying direction is set in the opposite direction. As a result, smooth circulation and conveyance of the developer can be maintained, and the same effect as in the other embodiments can be obtained.

  Other configurations other than the above, including the toner supply port, are the same as those in the first embodiment, and a description thereof will be omitted.

  Also in these forms of the developing device, it is preferable that the part of the rotating member corresponding to the developer delivery portion is formed into an impeller shape in order to smoothly circulate and convey the developer.

  Also in the second and third embodiments, the same can be obtained by making the outer diameter, rotation speed, peripheral speed, and virtual cross-sectional area of the second stirring member 807 larger or higher than that of the first stirring member. Compared with the case where it sets to, stirring performance can be improved.

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

  The image forming apparatus shown in FIG. 18 has toner recycling means (toner recycling apparatus) that collects the toner removed from the photosensitive drum after transfer, and finally returns it to the developing device for reuse.

  The image forming apparatus shown in FIG. 18 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, and a fixing device. However, these can be understood from the drawings and explanations relating to the first embodiment, and the developing device 8 has basically the same configuration as that of the first embodiment. The main parts are only shown schematically.

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

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

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

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

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

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

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

  As described in connection with the developing device in the first embodiment, the recycled toner supply port 825 is a substantially intermediate position where the first stirring member 805 and the second stirring member 807 face each other. It is provided on the cover 812 corresponding to an appropriate position further upstream than the toner supply port 813 in the developer transport direction by the stirring member 805.

  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 linear as shown in FIG. 19, which is a schematic diagram of the same developing device as shown in FIG. It is in. This relationship is the same in the second and third embodiments of the developing device.

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

  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 first stirring member 805, a sufficient mixing and stirring time is ensured in the second storage stirring portion 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 developer supply / recovery 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 first stirring 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.

  Note that the position of the toner supply port 813 or the recycled toner supply port 825 is shown on the upstream side when viewed in the developer conveying direction by the first stirring member 805 or the second stirring member 807 when the developing device of FIG. 16 is used. Yes, when the developing device of FIG. 17 is used, it is on the upstream side in the developer transport direction by the second stirring member.

  Further, the rotation directions of the first stirring member 805 and the second stirring member are axially rotated in the direction in which the peripheral surfaces of the first stirring member 805 and the second stirring member are moved from top to bottom in the same manner as the rotation direction in the first embodiment. The configuration is as described above.

  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 developer supply and recovery member, the first stirring member, and the second 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 outward in the radial direction to form a paddle shape, and further, disk-shaped flange members F having an outer dimension of 24 mm are provided at both ends of the rotating member. Rotating member configured.

  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 A2)
A rotating member having the same configuration as the rotating member A except that the maximum outer diameter is set to 26 mm based on the rotating member A.
(Rotating member C)
A rotating member having the same configuration as the rotating member A, except that the pitch (p) of the spiral ribs is 40 mm, based on the rotating member A.
(Rotating member D)
A rotating member having the same configuration as that of the rotating member A except that the pitch (p) of the spiral rib is set to 35 mm based on the rotating member A.
(Rotating member D2)
A rotating member having the same configuration as the rotating member D, except that the maximum outer diameter is increased to 26 mm based on the rotating member D.
(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 F 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 I)
As shown in FIG. 8, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, and a plurality of plate-like ribs (vertical blades) extending radially outward are provided in the longitudinal direction of the shaft. And four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the developer conveyance direction by the spiral ribs so as to extend radially outward to form a paddle shape. In addition, a rotating member having a configuration in which disk-shaped flange members F having an outer dimension of 24 mm are provided at both ends of the rotating member.

  The specifications of the rotating member I are as follows.

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

  The specifications of the rotating member L are as follows.

Maximum outer diameter (d): 24 mm, length in rotation axis excluding shaft portion: 440 mm, outer diameter of shaft member: 6 mm, pitch of spiral rib (p): 30 mm, thickness of spiral rib: 1 mm, Arrangement of plate-like ribs: two places at equal intervals in the circumferential direction, radial length of plate-like ribs (t): 5 mm, thickness of plate-like ribs: 1 mm
(Rotating member L2)
A rotating member having the same configuration as the rotating member L except that the maximum outer diameter is increased to 26 mm based on the rotating member L.
(Rotating member M)
As shown in FIG. 10, a left-handed spiral rib (screw) is formed on the outer peripheral surface of the shaft member, and a plate-like rib extending in the axial direction without a break on the outer peripheral edge of the spiral rib. And four flat blade members are provided on the outer peripheral surface of the shaft member extending 30 mm downstream in the developer conveyance direction by the spiral ribs so as to extend radially outward to form a paddle shape. In addition, a rotating member having a configuration in which disk-shaped flange members F having an outer dimension of 24 mm are provided at both ends of the rotating member.

  The specifications of the rotating member M 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: 4 positions at regular intervals in the circumferential direction, radial length of plate-like ribs (t): 3 mm, thickness of plate-like ribs: 1 mm
(Rotating member M2)
A rotating member having the same configuration as the rotating member M except that the maximum outer diameter is increased to 26 mm based on the rotating member M.
(Rotating member Q)
As shown in FIG. 11, plate ribs (flat blade members) extending radially outward and in the longitudinal direction of the shaft are provided from four equally divided portions in the circumferential direction of the shaft, thereby forming a cross paddle. A rotating member.

  The specifications of the rotating member Q 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, radial length of plate-like rib (h): 9 mm, thickness of plate-like member : 1mm
(Rotating member Q2)
A rotating member having the same configuration as the rotating member Q except that the maximum outer diameter is increased to 26 mm based on the rotating member Q.
(Rotating member S)
As shown in FIG. 6, a disc-shaped flange member F having a configuration in which a plurality of plate-like members having an elliptical shape in the axial direction are arranged and having an outer dimension of 24 mm is provided at both ends of the rotating member. Rotating member with a configuration.

  The specifications of the rotating member S are as follows.

Maximum outer diameter (d): 24 mm, length in the rotation axis direction excluding the shaft portion: 440 mm, outer diameter of the shaft member: 6 mm, thickness of the plate member: 1 mm, attachment angle 45 ° with respect to the shaft of the plate member, plate shape Arrangement pitch of members: 25mm
(Rotating member S2)
A rotating member having the same configuration as the rotating member S except that the maximum outer diameter is increased to 26 mm based on the rotating member S.
(Rotating member T)
As shown in FIG. 12, a plurality of elliptical plate-like members are arranged in the axial direction, and plate-like ribs extending in the axial direction are provided at equal intervals in the circumferential direction. A rotating member having a configuration in which a disc-shaped flange member F having an outer dimension of 24 mm is provided at both ends.

  The specifications of the rotating member T 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, mounting angle of plate member with respect to shaft: 45 °, plate Pitch of the plate-like members: 25 mm, radial length of the plate-like ribs (t): 3 mm, thickness of the plate-like ribs: 1 mm, attachment points of the plate-like ribs: four locations (equal intervals in the circumferential direction)
(Rotating member T2)
A rotating member having the same configuration as the rotating member T except that the maximum outer diameter is increased to 26 mm based on the rotating member T.
(Rotating member W)
As shown in FIG. 14, a first stirring unit and a second stirring unit configured by providing a plurality of semi-elliptical plate-like members so as to be inclined in different directions with respect to a plane perpendicular to the shaft member. And a rotating member having a disk-like flange member F having an outer dimension of 24 mm at both ends of the rotating 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
<Experimental example 1>
[Create developer]
Compared with the developing devices 1 to 10 according to the present invention in which the developer supply / recovery member, the first stirring member and the second stirring member are constituted by the rotating members shown in Table 1 in accordance with the configuration shown in FIGS. Developing devices 11 to 13 were prepared.

  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 are formed in the developing devices 1 to 10 and 11 to 13 at positions where the first stirring member and the second stirring member face each other (when viewed in a cross section perpendicular to the longitudinal direction, both members And a position 15 mm downstream from the upstream edge in the developer transport direction by the second stirring member.

  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.

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

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

  Each of the developing devices 1 to 13 is mounted on an appropriate driving machine, the rotation amount of the developer supply / recovery member is set to 300 rpm, and the rotation amounts of the first stirring member and the second stirring member are set as shown in Table 1 below. The developer transfer amount was measured.

  The results are shown in Table 1 below.

  The developer movement amount is measured by measuring the weight of the developer discharged per unit time from the developer discharge port provided on the bottom surface of the housing on the downstream side of the developer supply / recovery member in the developer transport direction. went.

  In Table 1, “the moving direction in the first / second opposing portion” indicates the moving direction of the two agitating members when viewed in the proximity of the first agitating member and the second agitating member.

  Further, for example, two types of numerical values are displayed for the rotation speeds of the developer supply / recovery member and the agitating member in the developing devices 1 to 13. The number of revolutions, 400 rpm, indicates the number of revolutions in monochrome image formation, and the results of the configuration in which each stage (upper stage, lower stage) can be traced horizontally are related to Tables 2 and 3 described later.

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

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

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

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

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

  The developing device numbers in Table 2 correspond to the developing device numbers in Table 1, and this is the same in Table 3 described later.

<Experimental example 2>
[Production of development device]
In each of the developing devices 1 to 13 used in Experimental Example 1, a recycled toner supply port was formed at a position 8 mm upstream from the toner supply port in the developer transport direction by the first stirring member or the second stirring member. Developing devices 1 to 13 (developing device numbers in all tables are unified for easy understanding of correspondence) were prepared.

  In the configuration shown in FIG. 18, an image forming apparatus for forming a monochrome image having toner recycling means mounted on each of the developing devices 1 to 13 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 the rotation speeds of the developer supply and recovery member, the first stirring member, and the second stirring member are set. The following (7) to (9) are set under the same image forming conditions as those in Table 1 (shown in the upper part of the corner developing device) and the image forming unit related to the black (BK) toner image in Experimental Example 1. The image output is repeated 8 times (A4 × 2000 in total), and the evaluation of the presence / absence of fogging of the character / line pattern, the presence / absence of the character scattering, and the presence / absence of in-machine contamination is described above by the image output test. In addition to the evaluation criteria described above, the presence / absence of occurrence of image density unevenness of the solid pattern was evaluated based on the following evaluation criteria. The results are shown in Table 3 below.
(7) Black (BK) single color characters / lines + halftone (10 steps) pattern (print rate 30%) are output in succession 50 sheets.
(8) Continuously output 150 black (BK) solid patterns (printing rate 80%).
(9) Black (BK) single-color character / line pattern (printing rate 7%) is output continuously 50 sheets.
<Evaluation criteria>
The image density unevenness is measured by measuring the relative reflection density at any nine locations in the black (BK) solid pattern page, the relative reflection density at all locations is 1.3 or more, and the maximum and minimum values. The case where the difference is 0.1 or less is “◯”, the minimum value of the relative reflection density is 1.2 or more and less than 1.3, and the difference between the maximum value and the minimum value is 0.1 or less “△”, and the case where the minimum value of the relative reflection density is less than 1.2 or the difference between the maximum value and the minimum value exceeds 0.15 is “x”.

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

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

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

  In particular, although not shown in the table, in the image forming apparatus provided with the toner recycling means, the rotation speed of the rotating member is increased (for example, 650 rpm or more) to obtain a sufficient developer moving speed, whereby the shaft When the configuration in which the occurrence of uneven image density with respect to the direction is suppressed, the image output test has to be stopped due to a significant increase in the stirring torque, and an output image cannot be obtained. As a result of investigating the cause, it was confirmed that the developer started to be fused to the shaft portion.

1 is a schematic diagram illustrating a first embodiment of an image forming apparatus according to the present invention. 1 is a plan view showing a first embodiment of a developing device according to the present invention. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is a schematic diagram which shows the 1st example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is a schematic diagram which shows the other example of a stirring member. It is the schematic which shows 2nd Embodiment of an image forming apparatus. FIG. 4 is a schematic diagram of a developing device for explaining a positional relationship between a toner supply port and a recycled toner supply port. It is a schematic diagram which shows 2nd Embodiment of a developing device. It is AA sectional drawing of FIG. It is the schematic which shows one structural example of the stirring member used in the experiment example. It is the schematic which shows the structure of the image development apparatus for a comparison. FIG. 4 is a schematic diagram illustrating 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 Developer supply and recovery member 805 First stirring member 807 First 2 Stirring member 810 Housing 812 Cover 813 Toner supply port

Claims (20)

A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer agitating section that is adjacent to the longitudinal direction of the developer supply / recovery member and can transport substantially the same amount of developer in the opposite direction to the developer transport direction by the developer supply / recovery member. A first stirring member provided in
A second agitating member adjacent to the longitudinal direction of the first agitating member on the side farther from the first agitating member with respect to the developer carrying member, and having no developer conveying ability in the rotation axis direction; A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the outer diameter of the second stirring member larger than the outer diameter of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer agitating section that is adjacent to the longitudinal direction of the developer supply / recovery member and can transport substantially the same amount of developer in the opposite direction to the developer transport direction by the developer supply / recovery member. A first stirring member provided in
A second agitating member adjacent to the longitudinal direction of the first agitating member on the side farther from the first agitating member with respect to the developer carrying member, and having no developer conveying ability in the rotation axis direction; A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
The rotational speed of the second stirring member is set to be higher than the rotational speed of the first stirring member, and the peripheral surface is determined by viewing the first stirring member and the second stirring member at their opposing proximity points. It can move from top to bottom, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer agitating section that is adjacent to the longitudinal direction of the developer supply / recovery member and can transport substantially the same amount of developer in the opposite direction to the developer transport direction by the developer supply / recovery member. A first stirring member provided in
A second agitating member adjacent to the longitudinal direction of the first agitating member on the side farther from the first agitating member with respect to the developer carrying member, and having no developer conveying ability in the rotation axis direction; A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the peripheral speed of the second stirring member higher than the peripheral speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device. The second stirring member has a plurality of plate-like members provided around the rotation axis and inclined in the same direction with respect to the rotation axis. 2. The developing device according to item 1. The said 2nd stirring member has a plate-shaped rib provided in the said rotating shaft direction around the rotating shaft or the said rotating shaft with the clearance gap, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The developing device according to item. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
Adjacent to the longitudinal direction of the developer supply / recovery member, and having a developer transport capability lower than the developer transport capability of the developer supply / recovery member, the developer transport direction of the developer supply / recovery member A first stirring member provided in the developer stirring unit that transports the developer in the opposite direction;
Whether the developer carrier is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and the developer conveying capability in the rotation axis direction is substantially the same as that of the first stirring member. Or a second stirring member that has a developer transport capability lower than that of the first stirring member and transports the developer in the same direction as the developer transport direction of the first stirring member;
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the outer diameter of the second stirring member larger than the outer diameter of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
Adjacent to the longitudinal direction of the developer supply / recovery member, and having a developer transport capability lower than the developer transport capability of the developer supply / recovery member, the developer transport direction of the developer supply / recovery member A first stirring member provided in the developer stirring unit that transports the developer in the opposite direction;
Whether the developer carrier is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and the developer conveying capability in the rotation axis direction is substantially the same as that of the first stirring member. Or a second stirring member that has a developer transport capability lower than that of the first stirring member and transports the developer in the same direction as the developer transport direction of the first stirring member;
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
The rotational speed of the second stirring member is set to be higher than the rotational speed of the first stirring member, and the peripheral surface is determined by viewing the first stirring member and the second stirring member at their opposing proximity points. It can move from top to bottom, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
Adjacent to the longitudinal direction of the developer supply / recovery member, and having a developer transport capability lower than the developer transport capability of the developer supply / recovery member, the developer transport direction of the developer supply / recovery member A first stirring member provided in the developer stirring unit that transports the developer in the opposite direction;
Whether the developer carrier is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and the developer conveying capability in the rotation axis direction is substantially the same as that of the first stirring member. Or a second stirring member that has a developer transport capability lower than that of the first stirring member and transports the developer in the same direction as the developer transport direction of the first stirring member;
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the peripheral speed of the second stirring member higher than the peripheral speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region where the first stirring member and the second stirring member are opposed to each other and in the region corresponding to the upstream side in the developer transport direction by the first stirring member. With a mouth,
A developing device. The second stirring member is provided around the rotation axis and a plurality of first plate-like members provided to be inclined in the first direction with respect to the rotation axis, and to be inclined in the second direction. The developing device according to claim 6, further comprising: a second plate-shaped member. The said 2nd stirring member has a plate-shaped rib provided in the said rotating shaft direction around the rotating shaft or with the rotating shaft and the clearance gap, The any one of Claim 6 thru | or 9 characterized by the above-mentioned. The developing device according to item. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer adjacent to the longitudinal direction of the developer supply / recovery member and in the same direction as the transport direction of the developer supply / recovery member with a developer transport capability lower than the developer transport capability of the developer supply / recovery member. A first stirring member provided in the developer stirring unit,
The developer carrying member is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and has a higher developer transport capability in the rotation axis direction than the developer supply and recovery member. And a second stirring member that conveys the developer in a direction opposite to the developer supply and recovery member,
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the outer diameter of the second stirring member larger than the outer diameter of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the first stirring member and the second stirring member facing each other, as viewed in the developer transport direction by the second stirring member With a mouth,
A developing device. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer adjacent to the longitudinal direction of the developer supply / recovery member and in the same direction as the transport direction of the developer supply / recovery member with a developer transport capability lower than the developer transport capability of the developer supply / recovery member. A first stirring member provided in the developer stirring unit,
The developer carrying member is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and has a higher developer transport capability in the rotation axis direction than the developer supply and recovery member. And a second stirring member that conveys the developer in a direction opposite to the developer supply and recovery member,
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the rotation speed of the second stirring member higher than the rotation speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the first stirring member and the second stirring member facing each other, as viewed in the developer transport direction by the second stirring member With a mouth,
A developing device. A developer carrier for carrying and conveying a developer including toner and a carrier;
A developer supply / recovery member provided in a developer supply / recovery unit, which is adjacent to the longitudinal direction of the developer carrier and can transport the developer in the direction of the rotation axis;
A developer adjacent to the longitudinal direction of the developer supply / recovery member and in the same direction as the transport direction of the developer supply / recovery member with a developer transport capability lower than the developer transport capability of the developer supply / recovery member. A first stirring member provided in the developer stirring unit,
The developer carrying member is adjacent to the longitudinal direction of the first stirring member on the side farther than the first stirring member, and has a higher developer transport capability in the rotation axis direction than the developer supply and recovery member. And a second stirring member that conveys the developer in a direction opposite to the developer supply and recovery member,
A housing for accommodating the developer carrier, the developer supply / recovery member, the first agitating member, and the second agitating member in a rotatable manner;
A developing device including a cover provided on an upper portion of the housing,
While setting the peripheral speed of the second stirring member higher than the peripheral speed of the first stirring member,
When the first stirring member and the second stirring member are viewed at their opposing proximity points, the peripheral surface is movable from above to below, and
Supplying toner for supplying toner onto the cover in a region corresponding to the upstream side of the first stirring member and the second stirring member facing each other, as viewed in the developer transport direction by the second stirring member With a mouth,
A developing device. The first agitating member is provided around the rotation axis and inclined in the second direction with a plurality of first plate members provided in the first direction with respect to the rotation axis. The developing device according to claim 11, further comprising: a second plate-like member. The said 2nd stirring member has a plate-shaped rib provided in the said rotating shaft direction around the rotating shaft or with the rotating shaft and the clearance gap, The any one of Claim 11 thru | or 14 characterized by the above-mentioned. The developing device according to item. 16. The developer carrier according to claim 1, wherein the developer carrying member and the developer supply / recovery member have circumferential surfaces that move in opposite directions when viewed from the opposing proximity points of the developer carrier and the developer supply / recovery member. Development device. 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 claims 1 to 16, wherein a developer including a toner and a carrier is used. An image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; and a developing unit that develops the electrostatic latent image into a toner image.
While using the developing device of any one of Claim 1 thru | or 17 as said image development means,
The moving speed of the image carrier is V [mm / sec], the maximum adhesion amount per unit area of the toner image formed on the image carrier is M [mg / cm ² ], and the direction orthogonal to the moving direction of the image carrier The maximum width of the toner image is L [mm], the developer movement amount in the rotation axis direction of the developer carrier by the developer supply / recovery member is Wo [g / sec], and the rotation speed of the developer supply / recovery member is R [ rpm] when Wo ≧ M · V · L / 1000
R ≦ 600
An image forming apparatus. An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image into a toner image, and a toner on the image carrier Transfer means for transferring an image to a transfer material or intermediate transfer member, cleaning means for cleaning the surface of the image carrier after transfer, and toner removed from the surface of the image carrier by the cleaning means are supplied to the developing means. In an image forming apparatus having toner recycling means for recycling
The developing device according to any one of claims 1 to 17 is used as the developing unit, and the developing device is on a cover of the developing device and corresponds between the first stirring member and the second stirring member. An image forming apparatus comprising a recycled toner supply port for supplying recycled toner at a position. 20. The image forming apparatus according to claim 19, wherein the recycled toner supply port is located upstream of the toner supply port as viewed in the overall developer movement direction (circulation movement direction) in the developer agitation unit. apparatus.

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