JP2003330278A - Image forming device and rotating developing means - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device and a rotating developing means which prevent the deterioration of a developer and unevenness of image density and stably coat a developer carrier with the developer and stabilize the image quality of a formed image with a simple constitution with respect to a color image forming device adopting a rotation switching type developing system using a two-component developer. <P>SOLUTION: A developing device 6M is provided with a developing vessel 65 for storing the developer therein, a developer carrier 61 which involves a fixed magnetic field generation means 62 and is rotated opposite an image carrier 1 at the time of developing operation and carries the developer, and a layer thickness control member 69 which is arranged below the developer image carrier 61 in the direction of gravity at the time of developing operation and controls the quantity of the developer carried like a layer on the developer carrier 61, and the magnetic field generation means 62 has a first magnetic pole N3 placed in the vicinity of a position opposed to the layer thickness control member 69 and a second magnetic pole N2 which has the same polarity as the first magnetic pole N3 and is adjacent to the first magnetic pole N3 above in the rotation direction of the developer carrier 61, and a developer quantity control member 610 is provided which is brought into contact with the developer carried on the developer carrier 61 in the vicinity of the second magnetic pole N2 and controls the quantity of the developer magnetically restrained in the vicinity of the second magnetic pole N2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mounts a developing device containing a two-component developer containing a toner and a carrier on a rotating body, and moves the developing device to a position facing the image carrier by the rotational movement of the rotating body. The present invention relates to an image forming apparatus such as a copying machine or a printer and a rotary developing means.

[0002]

2. Description of the Related Art In a conventional electrophotographic image forming apparatus, particularly an image forming apparatus for forming a chromatic image, a two-component developer containing a non-magnetic toner and a magnetic carrier is used as a developer. The component developing method is widely used. The two-component development method has advantages over other currently proposed development methods such as image quality stability and device durability, but on the other hand, deterioration of the developer due to long-term durability, especially deterioration of the carrier. Therefore, it is necessary to replace the developer.

A conventional developing device is shown in FIG. A developing device 60 using a two-component developer as the developer as shown in FIG.
In No. 0, the first conveying screw 63 and the second conveying screw 6 which are conveying means for conveying the two-component developer while stirring the two-component developer in the developing container 65.
Many 4 and 4 are arranged in the horizontal direction.

Of the two conveying means 63, 64, the first conveying screw 63, which is located closer to the photosensitive drum 1 which is the image carrier, supplies the developer to the developer carrier (developing sleeve) 61. It is used to collect the developer after passing through the developing section. The second conveying screw 64 is used for mixing and stirring the developer collected from the developing sleeve 61 and the newly supplied developer.

The developer supplied from the conveying screw 63 is pumped up to the developing sleeve 61 by the magnetic pole N1 located inside the developing container 65 of the magnet roller 62, which is a magnetic field generating means provided non-rotatably in the developing sleeve 61. As the developing sleeve 61 rotates, the developing sleeve 61
The developer container 6 passes above the magnetic pole S1 to the magnetic pole N2 in the portion where the developing sleeve 61 is exposed to the photosensitive drum 1 side.
5 is conveyed from the inside to the outside, and reaches the developing unit where the developing sleeve 61 and the photosensitive drum 1 face each other, which is the position of the developing magnetic pole S2. During the transportation, the developer is developed by magnetically regulating the layer thickness of the developer on the developing sleeve 61 in cooperation with the magnetic pole S1 located at a position opposite to it by the regulating blade 69 which is a layer thickness regulating member. Thinning of the agent is achieved and the electrostatic latent image is developed in the developing section.

After that, the developer left undeveloped in the developing section is conveyed into the developing container 65 by the magnetic pole N3 located downstream of the developing section in the rotating direction of the developing sleeve 61,
Adjacent magnetic poles N of the same pole located inside the developing container 65.
It is removed from the developing sleeve 61 by the repulsive magnetic fields of 1 and N3 and collected in the developing container 2.

In the developing device 600, the developer layer thickness regulation is achieved by using the regulation blade 69 which is a blade-shaped layer thickness regulation member. The regulation blade 69 is provided in the opening of the developing container 65 here. In the vicinity of the regulation blade 69 inside the developing container 65, the developer removed from the developing sleeve 61 by being scraped off by the blade 69 tends to accumulate. On the inside of the developing container 65 of the blade 69, there are two poles of an S1 pole facing the blade 69 of the magnet 62 fixed in the developing sleeve 61 and an N1 pole located upstream thereof in the rotating direction of the developing sleeve 61. Since the developer is held by the magnetic force generated by the blade 69, a large amount of the developer scraped off by the blade 69 is likely to be accumulated, and further, the developer is conveyed from the conveying screw 63 by the developing sleeve 61 one after another. Therefore, a large pressure is applied to the developer accumulated in a large amount to pressurize the magnetic carrier of the developer and the toner, and fine particles such as titanium oxide externally added to the toner are embedded in the toner.

Further, due to the friction between the toner and the magnetic carrier, the particle shape of the toner itself becomes rounded and rounded. In addition, when used for a long time, a so-called spent phenomenon occurs in which toner adheres to the surface of the magnetic carrier and cannot be removed.

When such developer deterioration occurs, the triboelectric charge amount of toner (so-called tribo) changes with use time, the developability of the toner changes, the image density changes, and the toner on the magnetic carrier or the photosensitive drum changes. The mechanical adhesion of the toner increases, making it difficult to perform development and transfer corresponding to the electric field, resulting in partial lack of toner (unevenness), which is extremely impressive when used and compared to the initial image. It was a bad image.

Therefore, in recent years, as a method of preventing the deterioration of the carrier, the amount of the two-component developer accumulated upstream of the layer thickness regulating member provided in the developing container is reduced, and the developer is conveyed one after another. As a means to prevent the deterioration of the developer by reducing the pressure applied to the developer by preventing it from coming in,
A so-called light load developing device has been proposed and implemented.

FIG. 6 shows a developing device of this light load configuration.
Magnet roller 62 used in the developing device 601
Is the first magnetic pole N3 arranged near the regulation blade 69.
And a second magnetic pole N2 of the same polarity that is adjacent upstream of the first magnetic pole N3 in the direction of rotation of the developing sleeve. Of the two magnetic poles N2 and N3 having the same polarity, in the vicinity of the facing position of the first magnetic pole N3. By restricting the developer with the restriction blade 69, the developer that is not applied to the developing sleeve 61 and remains without being retained by the first magnetic pole N3 quickly drops to the conveying screw 63. , Regulation blade 6
No large pool of developer is generated in the vicinity of the upstream side of the developing sleeve 61 in the rotation direction of No. 9.

By restricting the layer thickness of the developer at the position of the first magnetic pole on the downstream side of the repulsive pole inside the developing container 65 of the magnet 62 inside the developing sleeve 61, the developer is partially accumulated. The configuration to prevent is called a light load configuration.

Further, in the developing device 601, the developing sleeve 61 rotates so as to pass through the developing section from the bottom to the top. Here, the N3 pole arranged in the lower portion in the vertical direction serves as the first magnetic pole on the downstream side of the repulsion magnetic pole, and the regulation blade 69, which is a layer thickness regulation member, faces the N3 pole and has an appropriate distance from the developing sleeve 61. It will be placed. In the developing device having such a configuration, the regulating blade 69 can be arranged in the vicinity of the lowermost point in the vertical direction of the developing sleeve 61. In that case, the conveying screw 6 closer to the developing sleeve 61 can be arranged.
There is no need to pump up the developer against gravity from 3
The developer can be pumped up even if the amount of the developer existing in the conveying screw 63 is small. That is, stable pumping can be performed without depending on the amount of the developer in the developing container 65, so that the uneven thickness of the regulated developer layer can be reduced.

As described above, in the light load developing device, since the developer is dropped and removed between the first and second repelling electrodes, the developer is successively conveyed as in the conventional case, and a large pressure is applied. It does not affect the developer. Therefore, it is possible to prevent the deterioration of the developer.

On the other hand, in contrast to the two-component developing system, the one-component jumping developing system using magnetic toner does not use a carrier, so that it is not necessary to control the toner density in the developer.
Further, since there is no problem of deterioration of the carrier, it is not necessary to replace the developer, and a stable image can be obtained for a long period of time. On the other hand, there is a problem that it is difficult to use as a color toner because the magnetic substance is mixed.

Therefore, in order to combine the advantages of the above two developing methods, an image forming apparatus has been proposed which uses a fixed one-component jumping developing method for black and a rotation switching two-component developing method for color.

[0017]

However, the developing sleeve 61 stores the two-component developer by the above-mentioned rotary developing means and has a light load structure like the developing device 601 shown in FIG. The image forming apparatus configured to support the developing device, which regulates the layer thickness of the developer below, on the rotating body because it rotates so as to pass from the bottom to the top in the direction of gravity has the following problems.

As shown in FIG. 7, in the two-component developing device supported by the rotary developing means 6a, the rotary member 6c is rotated to a position close to the photosensitive drum 1 immediately before each developing device 601 performs the developing operation. Moving. At this time, the developing device 601
The two-component developer T therein moves in the direction of gravity inside the developing container 65 every time the developing device 601 moves while changing its posture due to the rotational movement of the rotating body 6c.

Here, in the developing device 601, the developing position X
The regulating blade 69 is arranged below the developing sleeve 61 in the direction of gravity. Therefore, when the developing device 601 is vertically inverted and moves to the symmetrical position Y with respect to the center of the rotating body 6c at the developing position X, the developer T at the position Y is in the vicinity of the second magnetic pole N2, that is, the developing sleeve. The state is biased above 61. A large amount of the developer when it subsequently rotates and reaches the developing position X is magnetically restrained by the second magnetic pole N2, so that the developer surface in the developing device 601 is extremely lowered. Become.

When the developing operation is started in this state, the coated state of the developer becomes unstable when the developing sleeve 61 starts to rotate, and as a result, there is a problem that an image defect occurs.

Therefore, an object of the present invention is to form a color image using a rotation-switching type rotary developing means in which a developing device containing a two-component developer is mounted on a rotating body and moved to a position facing the image carrier. In the apparatus, an image forming apparatus capable of preventing deterioration of a developer and uneven image density, stabilizing a coating state of the developer on a developer carrier, and stabilizing image quality of an image to be formed with a simple configuration, and To provide a rotary developing means.

[0022]

The above object can be achieved by an image forming apparatus and a rotary developing means according to the present invention. In summary, the first aspect of the present invention relates to an image carrier on which an electrostatic latent image is formed, and a developing method for developing the electrostatic latent image with a developer to form a developed image on the image carrier. In an image forming apparatus having a device and a rotating body that sequentially moves the developing device to a developing unit by rotational movement, the developing device includes a developing container that contains a developer containing toner and a carrier as a developer, A developer carrier that includes a fixed magnetic field generating means and rotates to face the image carrier during a developing operation and carries a developer, and a position below the developer carrier in the gravity direction during the developing operation. And a layer thickness regulating member that regulates the layer thickness of the developer carried in a layered manner on the developer carrying member, and the magnetic field generating means is provided in the vicinity of facing the layer thickness regulating member. Positioned first magnetic pole, rotation of the first magnetic pole and the developer carrier A second magnetic pole having the same polarity adjacent to each other in improved flow,
And a developer amount for controlling the amount of the developer that is in contact with the developer carried on the developer carrier near the second magnetic pole and is magnetically bound near the second magnetic pole. An image forming apparatus is provided which is provided with a regulating member.

A second aspect of the present invention is a developing device for developing an electrostatic latent image formed on an image bearing member by a developer, and a rotating member for sequentially moving the developing device to a developing section by a rotational movement.
In a rotary developing means having a developing container containing a developer containing a toner and a carrier as a developer and a fixed magnetic field generating means, the developing container is rotated so as to face the image carrier during the developing operation, A developer carrier to be carried, and a layer thickness which is arranged at a position below the developer carrier in the direction of gravity during the developing operation and regulates the layer thickness of the developer carried in layers on the developer carrier. A regulation member is provided, and the magnetic field generating means is provided with a first magnetic pole located in the vicinity of facing the layer thickness regulating member, and the first magnetic pole adjacent to the first magnetic pole upstream in the rotation direction of the developer carrier. And a second magnetic pole having a polarity, which is in contact with the developer carried on the developer carrier in the vicinity of the second magnetic pole and is magnetically restrained in the vicinity of the second magnetic pole. A developer amount regulating member for regulating the developer amount is provided. To provide a developing means.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The image forming apparatus and the rotary developing means according to the present invention will be described below in more detail with reference to the drawings.

Embodiment 1 An electrophotographic image forming apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. 1 is an overall schematic explanatory view of the electrophotographic image forming apparatus, and FIG. 2 is a schematic explanatory view of the constitution of the developing means.

The electrophotographic image forming apparatus according to this embodiment is
As shown in FIG. 1, a photosensitive drum 1, which is an electrophotographic photosensitive member having a photosensitive layer made of an organic photosensitive member formed on a cylindrical substrate as an image bearing member, has a predetermined circumference in the direction of arrow A in FIG. It is mounted so that it can rotate at a speed. In this embodiment, a photosensitive layer made of an organic photosensitive material is formed in the shape of an aluminum cylinder having an outer diameter of 50 mm, and a surface protective layer for improving the toner releasability and preventing the photosensitive layer from being scraped is provided. .

The peripheral surface of the photosensitive drum 1 is charged to a predetermined polarity and potential by a roller charger 2 which is a charging means.
Then, the charged surface is modulated (turned on) in response to the pixel signal of the image information output from the exposure unit 3 and input from the image signal generating device such as an image reading device or a personal computer (not shown) via the print interface. The laser light 4 that has been turned on / off is deflected by the laser light reflection mirror 5 and is irradiated onto the photosensitive drum 1 to perform scanning exposure, thereby forming an electrostatic latent image of image information. It

The developing means 6 includes a rotating body 6c, a yellow developing device 6Y, a magenta developing device 6M, and a cyan developing device 6C.
And a fixed developing means 6b having a black developing device 6B for black.

The yellow developing device 6Y, the magenta developing device 6M, and the cyan developing device 6C contain a two-component developer containing a non-magnetic toner (-polarity) and a magnetic carrier, and the mixing ratio thereof is approximately a weight ratio. It is about 1: 9,
Toner is replenished from the replenishing path (not shown) by the consumed amount. On the other hand, the black developing device 6B is a one-component jumping developing type developing device in which magnetic toner (-polarity) is stored.

The rotary developing means 6a is rotatably supported by a rotary support device 6c, which is a rotary member, in the direction of arrow B in FIG. 1, that is, in the forward direction with respect to the photosensitive drum 1, and on the peripheral surface of the rotary support device 6c. The above-described color developing devices 6Y, 6M, and 6C are arranged along the line, and the rotary supporting device 6c rotates to sequentially face the photosensitive drum 1 to perform development with toner of each color.

On the other hand, the fixed developing means 6b has a developing device 6B containing a large amount of black toner consumed as a developer, and is constructed so as to be detachable from the main body of the device. When the fixed developing means 6b is attached to the apparatus main body 7, as shown in FIG. 2, the developing sleeve 61b, which is a rotatable developer carrying member, has a minute gap (50 μm to 500 μm in the present embodiment) with the photosensitive drum 1. ), A developing region for supplying the toner carried by the developing sleeve 61b toward the photosensitive drum 1 is formed.

Further, the toner container 62b is provided with a feeding means 63b for feeding the toner to the developing sleeve 61b side, and a feeding roller 64b for feeding the toner fed by the feeding means 63b to the developing sleeve 61b. It is housed. For the supply roller 64b, a rubber foam material such as polyurethane or silicone is preferably used in order to achieve stable supply to the developing sleeve 61b and uniform toner application. Further, the supply roller 64b
It is preferable to rotate the developing sleeve 61b in the direction of the arrow in FIG. 2, which is the same direction as the rotating direction of the developing sleeve 61b, while causing the developing sleeve 61b to contact the developing sleeve 61b. or,
A developing blade 69b is provided above the developing sleeve 61b as a layer thickness regulating member for regulating the layer thickness of the toner carried on the developing sleeve 61b, and below the developing sleeve 61b is a lower portion of the toner container 62b. A blowout prevention sheet 66b is provided to prevent the toner from being blown from the outside to the outside.

In the construction of the developing means 6 described above, after the surface of the photosensitive drum 1 is charged by the roller charger 2, the exposure is ON / OFF controlled according to the image data of the first color (eg yellow). The exposure scanning by 4 is performed, and the electrostatic latent image of the first color is formed on the photosensitive drum 1.
The electrostatic latent image of the first color is developed and visualized by the yellow developing device 6Y containing the yellow agent of the first color. During the developing operation by the developing devices 6M, 6C, 6Y and 6B, a developing bias is applied from the power source 16 to the developing sleeves 61 and 61b.

Then, the visualized first developed image (toner image) is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force, and the peripheral speed of the photosensitive drum 1 is substantially the same speed ( In the present embodiment, the image is transferred onto the surface of the intermediate transfer body drum 8 at the nip portion between the photosensitive drum 1 and the intermediate transfer body drum 8 which is rotationally driven in the arrow D direction which is the forward direction at 100 mm / s). .

In this embodiment, the intermediate transfer member drum 8 is made of urethane resin in which carbon, fluorine resin or the like is dispersed on the surface of a conductive elastic layer made of NBR rubber or the like on an aluminum cylinder. The surface layer having releasability is formed to have a resistance value of about 10 ⁵ to 10 ¹⁰ Ωcm and an outer diameter of 153 mm.

At the time of transfer onto the intermediate transfer body drum 8, a preset voltage having a polarity opposite to the charging polarity (-) of the toner is applied to the drum 8. Toner remaining on the photosensitive drum 1 without being transferred to the intermediate transfer drum 8 at the time of this transfer is scraped off by a cleaning blade 9a provided in the cleaning unit 9 and pressed against the photosensitive drum 1, and waste toner It is collected in the container 9b.

Then, the above-mentioned transfer process is similarly repeated for other toners (magenta, cyan, black),
In each case, toner images of different color toners contained in the developing devices are sequentially transferred to the intermediate transfer body drum 8 and stacked, whereby a color image is compositely formed.

Cleaning means 9 for cleaning the surface of the photosensitive drum 1 after the toner image is transferred onto the intermediate transfer body drum 8.
Is for scraping off the toner remaining on the surface of the photosensitive drum 1 by bringing the cleaning blade 9a into contact with the surface of the photosensitive drum 1.

In FIG. 1, the toner remaining on the transfer material P without being transferred from the intermediate transfer body drum 8 by the cleaner 10 is removed from the intermediate transfer body drum 8.

The transfer material P as a recording material is fed from the feeding cassette 11 to the intermediate transfer drum 8 by the feeding roller 12.
a and the conveying roller 12b are fed one by one, and by applying a voltage having a polarity opposite to that of the toner from the back surface of the transfer material P to the transfer roller 13, the full-color toner on the intermediate transfer body drum 8 side is applied to the transfer material P. The image is transferred and formed.

Then, the transfer material P to which the full-color toner image has been transferred is separated from the intermediate transfer body drum 8 and introduced into the fixing means 14, where the toner image is heated and fixed and discharged to the discharge tray 15. It is configured.

Next, the structure of the two-component developing device, which is a characteristic part of this embodiment, supported by the rotary developing means 6a will be described with reference to FIG. Developing devices 6M and 6Y for each color
Since 6C has the same configuration, 6M will be described here.

The developing device 6M of this embodiment is provided with a developing container 65 containing a two-component developer containing a magnetic carrier and a non-magnetic toner, and the developing container 65 is a developer carrying member such as SUS. The developing sleeve 61 made of the non-magnetic material is provided so as to face the photosensitive drum 1 rotating in the direction of arrow A, which moves the developing portion downward in the direction of gravity. The developing sleeve 61 moves in a direction opposite to the photosensitive drum 1 at a portion facing the photosensitive drum 1,
In other words, in the direction of arrow C in the direction of the photosensitive drum 1 and counter,
The developing portion, which is a portion facing the photosensitive drum 1, is rotated so as to move from the lower side to the upper side in the gravity direction.

In the developing sleeve 61, there are five magnetic poles, that is, the main developing pole arranged opposite to the photosensitive drum 1 in this embodiment, the magnetic pole S1 and N1 in the rotation direction C of the developing sleeve 61 in this order. A magnet roller 62, which is a magnetic field generating means having magnetic poles of S2, N2, and N3, is non-rotatably provided. The developing container 6 is provided from the magnetic pole S2 to the magnetic pole N3.
5 is an internal area.

The developing container 65 has a partition wall 66, and the first chamber 6 has a partition wall 66.
7 and the second chamber 68 are divided into the first chamber 67 and the second chamber 68.
The developer carrying screws 63 and 64 are respectively disposed in the.

A regulating blade 69, which is a developer layer thickness regulating member, in the upper part of the first chamber 67 and below the developing sleeve 61 is N in the rotation direction C of the developing sleeve 61.
It is arranged so that the closest contact is located at a distance of 500 μm from the developing sleeve 61 on the 5 ° downstream side of the three poles.
The regulation blade 69 is made of only a magnetic material and is formed into a plate shape having a thickness of 1.5 mm.

The developer in the developing container 65 is the developing container 65.
While being agitated by the developer conveying screws 63 and 64 provided in, the developer is conveyed from the back side to the front side. At this time, a part of the developer is drawn up by the N3 pole (first magnetic pole) of the magnet roller 62. .

Here, the maximum magnetic flux density on the surface of the N3 pole developing sleeve 3 is 650 gauss, and the full width at half maximum of the magnetic flux density is 37 °.
Is. The drawn up developer is regulated to a layer thickness of about 30 mg / cm ² by the magnetic field between the regulation blade 69 and the N3 pole.

With the developer whose layer thickness is regulated, the latent image on the photosensitive drum 1 is developed in the vicinity of the S1 pole which is the developing pole. The developer that has passed through the developing section is conveyed to the N1, S2, and N2 poles (the magnetic flux density is, for example, 400 to 500 gauss),
Repulsion magnetic pole N2 pole (second magnetic pole) and N3 pole (first magnetic pole)
In the region where the magnetic flux density Br in the vertical direction on the developing sleeve 61 is 10 mT or less and the magnetic flux density Bθ in the horizontal direction is 10 mT or less, the toner falls from the developing sleeve 61, and the conveyance screw 63 located below the developing sleeve 61 causes the screw to move deeper. It is conveyed to the side and is passed to the conveying screw 64 through an opening (not shown).

As described above, the developing device 6M is
Similar to the developing device 601 described with reference to FIG. 6 in the conventional example, the developing container 6 of the magnet 62 in the developing sleeve 61.
5 has a first magnetic pole N3, which is a repulsive magnetic pole, and a second magnetic pole N2 upstream of the developing sleeve 61 in the rotational direction,
It has a light load configuration in which a regulating blade 69 which is a layer thickness regulating member is opposed to the first magnetic pole N3 on the downstream side, and the regulating blade 69 is provided below the developing sleeve 69 in the direction of gravity.
The developing device has a configuration capable of stably pumping up to the developing sleeve 61 even with a small amount of developer.

In the present invention, in the light-load developing device in which such a layer thickness regulating member is located below,
, The developing sleeve 6 is provided near the second magnetic pole N2.
1 is a developer amount regulating member 61 that regulates the amount of the developer that is magnetically restrained by the magnetic pole N2 by coming into contact with the developer carried on the magnetic recording medium 1.
0 is set.

As the developer amount regulating member 610, the magnetic pole N
A partition wall 66 is formed in the vicinity of the magnet 62 in the developing sleeve 61, here in the first chamber 67 having the screw 63, in such a shape as to come into contact with the entire length of the developer in the vicinity of 2.
Is provided above. As the material, a plastic such as ABS or PC or a non-magnetic metal such as Al is used, and the amount of the developer conveyed to the second magnetic pole N2 is regulated by the rotation of the developing sleeve 61. .

Next, with reference to FIG. 4, the developing device 6 of this configuration is used.
The behavior of the developer when it is mounted on the rotary developing means 6a using M and the rotation switching operation is performed will be described. When the developing device for performing the development is switched to another developing device 6Y or 6C mounted on the rotating body 6c of the rotating developing means 6a, the developing device 6M is rotated from the position X for performing the developing operation to rotate the rotating body 6c. It may move to a position Y that is symmetrical to the position X with respect to the center. Here, when moving to position Y,
The developing device M takes an upside down posture when it is at the position X,
The developer T inside the developing device M moves downward due to gravity.

However, since there is the developer amount regulating member 610, the developer T is reached to the point where the magnetic force of the second magnetic pole N2 acts.
Does not move. Therefore, when the rotation is switched to the position X where the developing operation is performed next time, the developer T moves to the second magnetic pole N.
Since it is not restricted by the magnetic force of 2, it almost falls to the stirring screw 63 side, the developer surface of the developing chamber 67 is maintained in a sufficiently high state, the defective coating of the developer T does not occur, and the defective image such as an image defect occurs. It is structured so that no problems will occur.

That is, even if the two-component developing device is rotated to the inverted position by rotation switching, the amount of the developer constrained by the second magnetic pole is regulated, so that when the developing device comes to the developing operation position thereafter. However, most of the developer drops to the stirring screw side, and the developer surface can maintain an appropriate height. Even in the color image forming apparatus using such a rotation switching type two-component developing method, It is possible to stabilize the coated state of the developer on the developer carrying member while preventing deterioration, and to realize stable image quality in a simple and fair manner.

Embodiment 2 With the construction of Embodiment 1, the amount of developer in the vicinity of the second magnetic pole can be regulated, but the change in the state of the developer due to a long-term image forming operation and the surface of the developing sleeve 61. When the layer thickness of the developer increases due to the change in the state, there may be a problem that the developer stays near the developer amount regulating member 610.

In this embodiment, in addition to the structure of the first embodiment, the distance between the developer amount regulating member 610 and the developing sleeve 61 is
The gap between the developing sleeve 61 and a portion other than the developer amount regulating member 610 facing the developing sleeve 61, for example, a developer scattering prevention member (not shown) arranged in the vicinity of the magnetic pole S2 is equal to or wider. With this configuration, the developer can be prevented from staying in the vicinity of the developer amount regulating member 610, and the effect of the first embodiment can be maintained for a long period of time.

Third Embodiment In the first and second embodiments, the developer amount regulating member 610 is constituted by a member different from the developing container 65, and there are problems that the assembling property of the apparatus is bad and the cost is high.

Therefore, in this embodiment, the developer amount regulating member 6 is used.
10 is integrated with the developing container 65 of the developing device 6M.

With the above structure, the same effects as those of the first and second embodiments can be easily achieved at low cost.

Although the developing devices of Examples 1 to 3 have been described as being installed in the image forming apparatus of FIG. 1, the developing device is supported by the rotating body and is opposed to the image carrier by the rotational movement of the rotating body. As long as it moves to the developing position, other configurations can be applied, and the configuration is not limited to that of FIG.

Further, the number of colors and the kinds of colors of the developer accommodated in the developing device mounted on the rotary developing means are not limited to the above, and any two-component developer containing carrier and toner may be used.

Like the image forming apparatus described in Embodiments 1 to 3 in which the two-component developing device having a light load structure is mounted on the rotary member, the magnetic field generating means inside the developer carrier is provided. By providing a developer amount regulating member in the vicinity of the second magnetic pole located on the upstream side of the repulsive magnetic pole inside the developing container, the amount of developer constrained by the second magnetic pole is regulated. The coating state of the developer on is stable, and good image quality can be maintained.

[0064]

As described above, the image forming apparatus and the rotary developing means of the present invention are provided with the rotating member for sequentially moving the developing apparatus to the developing section by the rotary motion, and the developing apparatus uses the toner as the developer. A developer carrier containing a developer containing a carrier and containing a fixed magnetic field generating means, and a developer on the developer carrier arranged at a position below the developer carrier in the gravity direction during the developing operation. A layer thickness regulating member for regulating the layer thickness is provided, and the magnetic field generating means includes a first magnetic pole located in the vicinity of facing the layer thickness regulating member, and the first magnetic pole and the developer carrying member upstream in the rotational direction. It is a light load configuration having an adjacent second magnetic pole of the same polarity, and is in contact with the developer carried on the developer carrier near the second magnetic pole, and magnetically near the second magnetic pole. Since a developer amount regulating member that regulates the amount of developer that is bound is provided In a color image forming apparatus using a rotation-switching two-component developing method, it prevents developer deterioration and image density unevenness, and further stabilizes the coated state of the developer on the developer carrying member, and Image quality stabilization can be realized and provided in a simple and fair manner.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a developing unit and an image forming unit according to the present invention.

FIG. 3 is a sectional view showing an example of a developing device according to the present invention.

FIG. 4 is an explanatory view showing a moving state of the developing device according to the present invention by a rotating body.

FIG. 5 is a sectional view showing an example of a conventional developing device.

FIG. 6 is a sectional view showing another example of a conventional developing device.

FIG. 7 is an explanatory view showing a moving state by a rotating body of another example of the conventional developing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image bearing member) 6 Developing means 6M, 6Y, 6C Developing device 6B Black developing device 6a Rotating developing means 6b Fixed developing means 6c Rotating body 61 Developing sleeve (developer carrying body) 62 Magnet (magnetic field generating means) 63 , 64 Conveying screw 65 Developing container 69 Control blade (layer thickness control member) 610 Developer amount control member

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H031 AC11 AC14 AC19 AC20 AC31                       AC33 AD03 AD11 AD13 BA04                       BB01 CA11 CA13 EA03 FA01                 2H077 AB02 AB13 AC02 AD06 AD13                       AD18 AD24 AD36 AE06 BA07                       BA08 CA02 EA01 FA19 GA13                 2H300 EB02 EB08 EB12 EB24 EF08                       EG02 EJ09 EJ15 EJ31 EJ33                       EJ37 EJ45 EJ51 GG12 GG29                       HH23

Claims (6)

[Claims] 1. An image carrier on which an electrostatic latent image is formed, a developing device for developing the electrostatic latent image with a developer to form a developed image on the image carrier, and a rotary motion. In an image forming apparatus having a rotating body that sequentially moves the developing device to a developing unit, the developing device includes a developing container that contains a developer containing toner and a carrier as a developer, and a fixed magnetic field generating unit. A developer carrier that is contained and rotates to face the image carrier during the developing operation and carries the developer, and is disposed at a position below the developer carrier in the gravity direction during the developing operation. A layer thickness regulating member that regulates the layer thickness of the developer carried in layers on the agent carrier, and the magnetic field generating means has a first magnetic pole located in the vicinity of facing the layer thickness regulating member. When,
A developer which has the first magnetic pole and a second magnetic pole of the same polarity that is adjacent in the upstream of the rotation direction of the developer carrier, and is carried on the developer carrier near the second magnetic pole. An image forming apparatus, comprising: a developer amount regulating member which regulates the amount of the developer magnetically restrained in contact with the second magnetic pole. 2. The image according to claim 1, wherein a gap between the developer carrying member and the developer amount regulating member is equal to or wider than a gap between the developer carrying member and a member other than the developer amount regulating member. Forming equipment. 3. The image forming apparatus according to claim 1, wherein the developer amount regulating member is formed integrally with the developing container. 4. A rotary developing means comprising: a developing device for developing an electrostatic latent image formed on an image bearing member with a developer; and a rotating member for sequentially moving the developing device to a developing portion by rotational movement. A developer carrier for containing a developer containing a developer containing toner and a carrier as a developer and a fixed magnetic field generating means, and rotating so as to face the image carrier during a developing operation and carry the developer. And a layer thickness regulating member that is disposed at a position below the developer carrying member in the direction of gravity during the developing operation and that regulates the layer thickness of the developer carried in a layered manner on the developer carrying member,
The magnetic field generating means includes a first magnetic pole located in the vicinity of facing the layer thickness regulating member, and a second magnetic pole of the same polarity that is adjacent to the first magnetic pole upstream in the rotation direction of the developer carrying member. And a magnetic pole which is in contact with the developer carried on the developer carrier in the vicinity of the second magnetic pole, and regulates the amount of developer magnetically bound near the second magnetic pole. A developing device for regulating the amount of developer is provided. 5. The rotary development according to claim 4, wherein the gap between the developer carrying member and the developer amount regulating member is the same as or wider than the gap between other members than the developer amount regulating member. means. 6. The rotary developing means according to claim 4, wherein the developer amount regulating member is formed integrally with the developing container.