JPH11327308A - Developing device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a low-cost developing device that can provide a margin for the delivery of a developer with a simple configuration. The present invention relates to a delivery magnetic pole fixedly provided in a first developing roller, for delivering a developer to a second developing roller over a rotation direction of the first developing roller. S
1 and a first magnet 2 having a first peeling pole S2 for peeling the developer having the same polarity as the transfer magnetic pole S1.
2 and a second magnetic pole N2 fixedly provided on the second developing roller 6 and having a receiving magnetic pole N2 opposite in polarity to the transferring magnetic pole S1 for receiving the developer transferred from the first developing roller 5. A first magnet 22 including a magnet 24;
A second separation pole S3 having the same polarity as the first separation pole S2 was provided between the delivery magnetic pole S1 and the first separation pole S2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing device provided in, for example, an electrophotographic copying machine.

[0002]

2. Description of the Related Art In recent years, in the field of electrophotographic copying machines, there has been a remarkable increase in printing speed regardless of printers / copiers, digital machines, color machines, and monochrome machines.

However, when the speed of an electrophotographic copying machine is increased,
Since the photoconductor speed, that is, the process speed, becomes faster,
For the developing device, the amount of development per unit time (the amount of toner adhering to the photoreceptor) is reduced, so that the printing performance is basically reduced. In other words, the image density of the printing paper decreases.

In addition, from the standpoint of the photoreceptor, if the speed is increased due to problems such as sensitivity, the diameter of the photoreceptor must be increased. When the diameter of the photoreceptor is increased, the image quality is deteriorated such as chipping after the image. As described above, when the speed is increased, problems such as a decrease in image density and deterioration of image quality occur. In order to solve the problem, a so-called multiple developing device in which a plurality of developing rollers are arranged vertically in a single developing device. Are applied.

The plurality of developing devices are of a type in which a developer is conveyed on the back surface of a developing roller. Lubricant developer exchange between a mixer section as a developer stirring section and a developing roller section as a developer developing section, ie, developing It is a very difficult device to form an ideal developer flow when the entire developer is considered.

Therefore, it has been difficult to improve the developing characteristics of this type of developing device. However, as compared with a single developing device having a single developing roller, the developing characteristics are superior. In order to improve the flow of the developer, there has been developed a device in which a conveying magnet roller is provided at an intermediate portion between upper and lower developing rollers and a stirring member (for example, a paddle, a packet roller, or the like).

The role of the transport mag roller is to receive a fresh developer from the stirring member and transfer it to a developing roller (for example, an upper developing roller) that actually performs development, and does not actually perform development.

The provision of the transfer magnet roller eliminates the necessity of transferring the rear surface of the upper and lower developing rollers, and makes it possible to replace the developer agitating portion and the developer developing portion smoothly, that is, an ideal case when considering the entire developer. It is possible to form a flow, and it is possible to bring out remarkable development characteristics.

[0009]

As described above, when a plurality of developing devices are used, remarkable developing characteristics can be obtained as compared with a single developing device. However, a developing roller on a developing upstream side and a developing roller on a developing downstream side can be obtained. The transfer of the developer to is the largest structural point.

Therefore, it is necessary for the device to give a sufficient margin to this point. Ideally, all of the developer from the upstream developing roller is delivered to the downstream developing roller (100).
%) And that the developer (toner, carrier) does not scatter toward the photoconductor when the developer is delivered (no developer scatter).

A description will be given of the first 100% delivery. If 100% of the developer is not transferred, the thickness of the developer layer on the upstream / downstream developing roller changes during development, and the developing characteristics become very unstable.

Since the thickness of the developing layer is very important for the developing device, the thickness is adjusted to the order of 1/100 millimeter by a regulating plate usually called a doctor. When the thickness of the developing layer changes, overall image quality (for example, image density, fogging, fine line reproducibility, chipping at the trailing end) changes, and the toner scattering level may be abnormal.

Further, if 100% of the developer is not transferred, the developer after development is transported to the rear side of the upstream developing roller (conveyed to the rear side), and this is used again for development and a blurred image (thin image) ) Occurs.

Further, the balance of the flow of the entire developer may be lost, and an unexpected situation such as a drop of the developer or a jump of the developer may occur. Further, if 100% of the developer is not delivered, the amount of the developer on the downstream developing roller is reduced, so that a conveyance failure occurs. Thus, 100% of the developer
Percent delivery is absolutely necessary.

Next, a description will be given of the case where the developer is not scattered.
The developer scattering is a phenomenon in which the toner and the carrier of the developer component are scattered toward the photoreceptor and jump out of the developing device. If toner is scattered, the inside of the machine will be soiled.If the paper transport path is soiled, paper stains will occur, if wires etc. are soiled, leaks and output failures will occur, and if the light source system is soiled, illuminance will be reduced and will not serve as an electrophotographic device. Is possible.

When the carrier scatters, firstly, the amount of the developer in the developing unit decreases. When the depth of insertion decreases, the toner density becomes unstable, and defective images such as blade traces and stickiness occur.

Second, if the carrier jumps out of the developing device, various adverse effects are caused. If it adheres to the photosensitive drum, cleaning failure, leakage, an image adhered to the carrier and the like occur, and if it adheres to the fixing device, roller damage occurs.

As described above, if a plurality of developing devices are ideally constructed, special developing characteristics can be obtained. However, if there is no margin, 100% delivery cannot be performed. The developer may be scattered and the electrophotographic function itself may be impaired in addition to the developing characteristics.

Therefore, conventionally, it has been applied to products by the following method. The point at which 100% of the developer is delivered and the developer is not scattered is the magnetic force pattern of the delivery section from the upstream developing roller to the downstream developing roller.

The magnetic force pattern is a relationship between the magnetic force and the magnetic pole angle of the magnetic pole involved in the transfer of the upstream developing roller and the magnetic force and the magnetic pole angle of the magnetic pole involved in the transfer of the downstream developing roller.

FIG. 8 shows a model of the magnetic force pattern.
In FIG. 8, reference numeral 30 denotes a photosensitive drum.
0, the upstream and downstream developing rollers 31 and 32 are closely opposed to each other. Reference numeral 33 denotes an agitating member for agitating the developer. The developer agitated by the agitating member 33 is received by the conveying mag roller 34 and delivered to the upstream developing roller 31 which actually performs development. .

Here, the magnetic pole angles of the upstream and downstream developing rollers 31, 32 will be considered. In the figure,
When the magnetic pole is located at the target angle, that is, when the transfer pole S of the upstream developing roller 31 is located at the point and the receiving pole N of the downstream developing roller 32 is located at the point, the developer 10 % And the developer is not scattered.

However, in practice, deflection occurs at the positions of the magnetic poles S and N as shown in FIG.
As an example, in general, the deflection of the magnetic poles S and N of the developing rollers 31 and 32 themselves is ± 5 °, and the deflection when the developing rollers 31 and 32 are installed in the developing device is ± 2 °, and the deflection is about ± 7 ° in total. Occurs.

In FIG. 1, for example, when the upstream delivery pole S touches the downstream reception pole N, scattering of toner occurs. The upstream delivery pole S and the downstream reception pole N become (1).
In the case of touching 0), carrier scattering occurs, and in the case where the delivery pole S on the upstream side touches the receiving pole N on the downstream side, transport failure occurs.

Therefore, conventionally, the manufacturing variation of the developing rollers 31 and 32 has been set to ± 3 °, and the installation deviation of the developing rollers 31 and 32 has been set to ± 0.5 ° by providing a magnetic pole calibration mechanism.

That is, the deflection of ± 7 ° was suppressed to about 3.5% to ± 3.5 °, thereby preventing the above two problems. Further, since the gap between the upstream developing roller 31 and the downstream developing roller 32 is also involved in the above-mentioned problem, the margin may be secured with strict gap accuracy.

As described above, measures have been taken to reduce the manufacturing variation of the developing rollers 31 and 32, to provide a magnetic pole calibration mechanism, and to make the gap between the upper and lower developing rollers 31 and 32 highly accurate. All of these have led to considerable cost increases. That is, the current plurality of developing devices have high performance and high cost.

To summarize the conventional problems, a margin cannot be taken for the transfer of the developer from the upstream developing roller to the downstream developing roller in terms of performance. It was inevitable.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-cost developing apparatus which can provide a margin for the delivery of a developer with a simple structure. .

[0030]

According to the present invention, in order to solve the above-mentioned problems, the image forming apparatus according to the first aspect of the present invention is arranged so as to face a rotating image carrier along a rotating direction thereof and rotate in the same direction. First and second developing rollers for transporting and supplying a developer to the image carrier, and fixedly provided in the first developing roller, wherein the first developing roller and the second developing roller extend in a rotation direction of the first developing roller. A first magnet having a delivery magnetic pole for delivering the developer to the second developing roller and a first peeling pole for peeling the developer with the same polarity as the delivery magnetic pole; A second magnet fixedly provided on the developing roller and having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole for receiving the developer delivered from the first developing roller; The delivery magnetic pole and the first The position to said first separating pole having the same polarity second separating pole of between Hanarekyoku provided at least one or more poles.

According to a second aspect of the present invention, the first and the second image bearing members are conveyed and supplied to the image carrier by rotating and rotating in the same direction with respect to the rotating image carrier. A second developing roller, a stirring and conveying unit that stirs and conveys the developer toward the first and second developing rollers, and conveys the developer stirred and conveyed by the stirring and conveying unit to the first developing roller. A transfer roller, a transfer magnetic pole fixedly provided in the first developing roller, and a transfer magnetic pole for transferring the developer to the second developing roller over a rotation direction of the first developing roller. A first magnet having a first peeling pole for peeling the developer having the same polarity as the transfer magnetic pole, and a first magnet fixedly provided on the second developing roller and delivered from the first developing roller. Received developer A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole, wherein the first magnet is located between the delivering magnetic pole and a first separation pole in the first magnet. A second peeling pole having the same polarity as the peeling pole was provided near the delivery magnetic pole.

According to a third aspect of the present invention, the first and the second image bearing members are conveyed and supplied to the image carrier by rotating in the same direction as the rotating image carrier. A second developing roller, a stirring and conveying unit that stirs and conveys the developer toward the first and second developing rollers, and conveys the developer stirred and conveyed by the stirring and conveying unit to the first developing roller. A transfer roller, a transfer magnetic pole fixedly provided in the first developing roller, and a transfer magnetic pole for transferring the developer to the second developing roller over a rotation direction of the first developing roller. A first magnet having a first peeling pole for peeling the developer having the same polarity as the transfer magnetic pole, and a first magnet fixedly provided on the second developing roller and delivered from the first developing roller. Received developer A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole, wherein the first magnet is located between the delivering magnetic pole and a first separation pole in the first magnet. A second peeling pole having the same polarity as the peeling pole is provided, a first line segment connecting the center of the first developing roller and the delivery magnetic pole, a center of the first developing roller and the second line. The second separation pole was brought close to the delivery magnetic pole so that the absolute value of the angle formed by the second line segment connecting to the separation pole was 35 ° or less.

According to a fourth aspect of the present invention, the first and the second image bearing members are conveyed and supplied to the image carrier by rotating the image carrier in the same direction as the rotating image carrier. A second developing roller, a delivery magnetic pole fixedly provided in the first developing roller, for delivering the developer to the second developing roller, and a developer having the same polarity as the delivery magnetic pole. A first magnet having a first peeling pole for peeling off, and a delivery magnetic pole fixedly provided on the second developing roller and receiving a developer delivered from the first developing roller; And a second magnet having a receiving magnetic pole of opposite polarity, wherein the magnetic flux density in the normal direction of the transfer magnetic pole is U Gauss, and the magnetic flux density in the normal direction of the magnetic pole is L gauss. , LU ≧ 50
Gaussian.

According to a fifth aspect of the present invention, the first and the second image bearing members are arranged so as to face the rotating image carrier along the direction of rotation and rotate in the same direction to convey the developer and supply the developer to the image carrier. A second developing roller, a delivery magnetic pole fixedly provided in the first developing roller, for delivering the developer to the second developing roller, and a developer having the same polarity as the delivery magnetic pole. A first magnet having a first peeling pole for peeling off, and a delivery magnetic pole fixedly provided on the second developing roller and receiving a developer delivered from the first developing roller; Has a second magnet having a receiving magnetic pole of opposite polarity, and when a gap between the first and second developing rollers is X mm, X ≦
1.5 mm.

According to a sixth aspect of the present invention, the first and the second image bearing members are arranged so as to face the rotating image carrier along the rotating direction thereof, and rotate in the same direction to convey the developer and supply the developer to the image carrier. A second developing roller, a delivery magnetic pole fixedly provided in the first developing roller, for delivering the developer to the second developing roller, and a developer having the same polarity as the delivery magnetic pole. A first magnet having a first peeling pole for peeling off, and a delivery magnetic pole fixedly provided on the second developing roller and receiving a developer delivered from the first developing roller; And a second magnet having a receiving magnetic pole of opposite polarity, wherein the magnetic flux density in the direction normal to the magnetic pole for transfer is U Gauss, the magnetic flux density in the direction normal to the magnetic pole for receiving is L Gauss, Gap between the first and second developing rollers The when the X mm, L over U ≧ 50 gauss, and X ≦ 1.5 mm.

According to a seventh aspect of the present invention, the first and second rotating members are arranged so as to face the rotating image carrier and rotate in the same direction to convey the developer and supply it to the image carrier. A second developing roller, a stirring and conveying unit that stirs and conveys the developer toward the first and second developing rollers, and conveys the developer stirred and conveyed by the stirring and conveying unit to the first developing roller. A transfer roller, a transfer magnetic pole fixedly provided in the first developing roller, and a transfer magnetic pole for transferring the developer to the second developing roller over a rotation direction of the first developing roller. A first magnet having a first peeling pole for peeling the developer having the same polarity as the transfer magnetic pole, and a first magnet fixedly provided on the second developing roller and delivered from the first developing roller. Received developer A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole, wherein the first magnet is located between the delivering magnetic pole and a first separation pole in the first magnet. A second peeling pole having the same polarity as the peeling pole is provided, and the magnetic flux density in the normal direction of the transfer magnetic pole is U Gauss,
Assuming that the magnetic flux density in the normal direction of the receiving magnetic pole is L gauss and the gap between the first and second developing rollers is X mm, LU ≧ 50 Gauss and X ≦ 1.5 mm.

According to an eighth aspect of the present invention, the first and the second image bearing members are conveyed and supplied to the image carrier by rotating the same in the same direction. A second developing roller, a stirring and conveying unit that stirs and conveys the developer toward the first and second developing rollers, and conveys the developer stirred and conveyed by the stirring and conveying unit to the first developing roller. A transfer roller, a transfer magnetic pole fixedly provided in the first developing roller, and a transfer magnetic pole for transferring the developer to the second developing roller over a rotation direction of the first developing roller. A first magnet having a first peeling pole for peeling the developer having the same polarity as the transfer magnetic pole, and a first magnet fixedly provided on the second developing roller and delivered from the first developing roller. Received developer A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole, wherein the first magnet is located between the delivering magnetic pole and a first separation pole in the first magnet. A second peeling pole having the same polarity as the peeling pole is provided, a first line segment connecting the center of the first developing roller and the delivery magnetic pole, a center of the first developing roller and the second line. The second separation pole is brought close to the delivery magnetic pole so that the absolute value of the angle formed by the second line segment connecting the separation pole and the second line segment is 35 ° or less, and the magnetic flux in the normal direction of the delivery magnetic pole When the density is U Gauss, the magnetic flux density in the normal direction of the receiving magnetic pole is L Gauss, and the gap between the first and second developing rollers is X mm, LU ≧ 50 Gauss, X ≦ 1.5 mm
And

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 is a configuration diagram showing a photosensitive drum 1 as an image carrier and a developing device 2 opposed to the photosensitive drum 1.

The photosensitive drum 1 has a thickness of, for example, 2.5 m.
m, an outer peripheral surface of an aluminum cylinder having an outer diameter of 59.96 mm is coated with a photosensitive layer to give an outer diameter of about 60 mm. The photosensitive drum 1 is provided with a length of 340 mm so that the long side of the A4 size paper is conveyed in a direction in which the long side of the sheet is transported in a direction orthogonal to the traveling direction. Is rotated clockwise at the speed shown by the arrow.

The developing device 2 has a housing 4 in which a two-component developer composed of a toner and a carrier is accommodated. An upper developing roller 5 and a lower developing roller 6 as first and second developing rollers are disposed on the front side in the housing 4. The upper and lower developing rollers 5 and 6 are arranged along the rotation direction of the photosensitive drum 1 and are closely opposed to the photosensitive drum 1. The upper and lower developing rollers 5 and 6 are rotated counterclockwise as indicated by arrows to supply the developer to the photosensitive drum 1.

The surface of the lower developing roller 6 is in contact with a release sheet metal 8 for removing residual toner. Further, first and second mixers 10 and 11 that stir and convey the toner supplied from a toner supply hopper (not shown) are disposed on the inner side of the housing 4. Further, between the first mixer 10 and the lower developing roller 6, a stirring supply paddle 1 for stirring and supplying the developer sent from the first mixer 5.
3 is provided rotatably. This stirring supply paddle 1
A conveying magnet roller 15 that conveys the developer sent from the stirring supply paddle 13 to the upper developing roller 5 is provided rotatably in an obliquely upper portion of 3. A doctor blade 16 that regulates the layer thickness of the developer on the surface of the conveyance magnet roller 15 is closely opposed to the conveyance magnet roller 15.

Next, the developer (powder in which toner and carrier are mixed at a predetermined ratio) in the developing device 11
Will be described. The developer charged in the housing 4 is transported by the second mixer 11 to the back (or front) in the direction orthogonal to the plane of FIG. On the other hand, the first mixer 10 conveys the developer conveyed by the second mixer 11 in the opposite direction, that is, on the front side (or the back side) in the direction orthogonal to the plane of FIG. Therefore, the first
By the rotation of the second mixers 10 and 11, the developer charged into the housing 4 is circulated in the housing 4 and frictionally charged to a predetermined potential.

The developer circulated in the housing 4 by the rotation of the first and second mixers 10 and 11 is agitated and conveyed by the rotation of the agitating / supply paddle 13 and sent to the conveying magnet roller 15. The developer sent to the transfer magnet roller 15 is the doctor blade 1
After the layer thickness is regulated to be constant by 6, it is sent to the upper developing roller 5. The developer sent to the upper developing roller 5 is supplied to the electrostatic latent image on the photosensitive drum 1 while being conveyed to the lower developing roller 6 by the rotation of the upper developing roller 5 to perform development. After the development, the developer remaining on the lower developing roller 6 is removed by the release sheet metal 8, sent to the stirring / supply paddle 13, and then returned to the process of frictional charging by the first and second mixers 22 and 23 again. .

In this frictional charging step, an amount of toner corresponding to the difference between the toner density detected by a toner density sensor (not shown) and the reference value is supplied from a toner tank (not shown), The toner is stirred and frictionally charged by the second mixers 10 and 11, and is again supplied to the upper developing roller 5 via the stirring / supply paddle 13 and the conveying magnet roller 15.

FIG. 2 shows the structure of the upper and lower developing rollers 5 and 6. The upper developing roller 5 has a rotating sleeve 21, in which a first magnet 22 is fixedly provided. First magnet 2
2 is provided with a main pole N1 close to the photosensitive drum 1,
A delivery pole S1 and a first separation pole S2 are arranged at a predetermined interval downstream of the main pole N1 in the rotation direction of the rotary sleeve 21. The second separation pole S3 is provided between the delivery pole S1 of the first magnet 22 and the first separation pole S2 in a state of being close to the delivery pole S1.

The lower developing roller 6 has a rotating sleeve 23, in which a second magnet 24 is fixedly provided. Second magnet 24
Is provided with a receiving pole N2 for receiving the developer transferred from the upper developing roller 5, and further provided with a transport pole S4 on the downstream side in the rotation direction of the rotary sleeve 23 of the receiving pole N2.

Next, as a developer, a two-component material, developer D-6550 manufactured by Toshiba (carrier having a particle diameter of 65 μm, 40,000)
0 USED) and Toshiba toner T-6550 (particle size 11)
μm), and the test environment is an H / H environment (30 °, 85 RH), which is the worst condition for the developer transportability.
%) Will be described in comparison with the conventional apparatus shown in FIG.

FIG. 3 shows a magnetic pole pattern of the conventional upper developing roller 5. In the case of the magnetic pole pattern in FIG. 3, a point where there is no problem in the transfer of the developer exists only in a region of about ± 3 ° as indicated by α ゜ in the figure.

In the case of the magnetic pole pattern according to the present invention shown in FIG. 2, the point at which there is no problem in the transfer of the developer has been expanded to a region of about ± 10 ° as indicated by β ° in the figure.
The most important point of the present invention is that a separation pole S3 which does not exist in the normal (conventional) magnetic pole pattern is provided close to the transfer pole S4 between the transfer pole S1 and the separation pole S2.

FIGS. 4 and 5 show the reason why the provision of the peeling pole S3 has improved the margin of the developer delivery more than twice.
It will be explained in. FIG. 4 is a schematic diagram showing a magnetic force pattern in the normal direction of the upper developing roller 5 of the conventional device.

The peeling of the developer in FIG.
And the separation pole S2. The position where the developer is completely removed from the upper developing roller 5 is the bottom position (b) in FIG. 4, that is, the point where the magnetic force is the smallest.

However, in the case of this magnetic force pattern, the bottom position (b) is from the closest position of the upper developing roller 5 and the lower developing roller 6 to the downstream side in the developer conveying direction. All the developer is peeled off,
The developer is not completely removed at the closest position, that is, at the transfer section. Therefore, the delivery of the developer to the lower developing roller 6 is not complete.

FIG. 5 is a schematic diagram showing a magnetic force pattern in the normal direction of the upper developing roller 5 of the present invention. FIG.
Is carried out twice between the delivery pole S1 and the peeling pole S3 and between the peeling pole S3 and the peeling pole S2, so that the peeling effect alone is improved.

In addition, the developer is completely removed from the developing roller 5.
The position at which the film is peeled off from the bottom is the bottom position (b ') in the drawing, that is, the vicinity of the closest position of the upper developing roller 5 and the lower developing roller 6, or in other words, the vicinity of the developer transfer section.

Therefore, most of the peeled developer is conveyed to the receiving pole N2 of the lower developing roller 6, so that the delivery is completed. In the present embodiment, when the main pole N1 of the upper developing roller 5 is set to 0 ° and considered clockwise, FIG.
S2 pole = 170 °, S3 pole = 273 °, S1 pole = 30
6 cm.

That is, the magnetic pole S3 is | S1−S3 | ≧ = 35.
The smaller the value of ゜, the closer to the S1 pole. FIG.
Shows a second embodiment of the present invention.

In this embodiment, the magnetic flux density in the normal direction of the transfer pole S1 of the upper developing roller 5 is U [Gauss], and the magnetic flux density in the normal direction of the receiving pole N2 of the lower developing roller 6 is L [Gauss]. And the gap between the upper and lower developing rollers 5 and 6 is X [mm].
, L−U ≧ 50 gauss and X ≦ 1.5 mm.

Next, as a developer, a two-component material, Toshiba Developer D-6550 (particle size: 65 μm, carrier: 40000)
0 USED) and Toshiba toner T-6550 (particle size 11)
μm), the H / H environment (30 °, 85 RH%), which is the worst condition for transportability, was selected as the test environment. The experiment shown in FIG. 7 was obtained when the experiment was performed using the gap between the parameters as a parameter.

That is, regarding the magnetic flux densities U and L, it is better that the Gauss of the magnetic pole N2 on the receiving side is strong.
The result is that the smaller the gap X between 6, the better.

As shown in the figure, in this test result, X ≦ 1.
With 5 mm and LU ≧ 50 Gauss, a good area, that is, an area where the delivery is complete could be found. The present invention is not limited to the first and second embodiments, but may be a combination of the first and second embodiments. That is, the delivery pole S1 and the separation pole S2 A separation pole S3, which does not exist in the normal magnetic force pattern, is provided close to the delivery pole S4.
The magnetic flux density in the normal direction is U [Gauss], and the lower developing roller 6
When the magnetic flux density in the normal direction of the receiving pole N2 is L [Gauss] and the gap between the upper and lower developing rollers 5 and 6 is X [mm], L−U ≧ 50 Gauss and X ≦ 1.5 mm .

Although both the first embodiment and the second embodiment are sufficiently effective alone, the first and second embodiments are not limited.
In order to cope with the high-speed rotation and small diameter of the developing rollers 5 and 6 described above, a further margin is required, so that the third embodiment is required.

The present invention has the same effect when Vm2 / Vm1> 1 when the rotation speed of the upper developing roller 5 is Vm1 and the rotation speed of the lower developing roller 6 is Vm2.
As described above, according to the present invention, in a plurality of developing devices, a magnetic force constituting mechanism is provided, a hard developing roller having a narrow magnetic force space is used, and a gap in a very narrow space between upper and lower developing rollers is maintained. The transfer of the developer from the upstream developing roller 5 to the downstream developing roller 6 can be transferred 100% without any trouble such as image quality deterioration, conveyance failure, and scattering under the condition that the expensive gap maintaining mechanism is not provided. I can do it. Accordingly, a high-performance and low-cost multiple developing device can be provided.

[0063]

As described above, according to the present invention, the first magnet of the first developing roller is located between the delivery magnetic pole and the first peeling pole and has the same polarity as the first peeling pole. Since at least one second peeling pole is provided, the peeling of the developer is performed between the delivery magnetic pole and the second peeling pole and between the second peeling pole and the first peeling pole.
Of the developer, and the developer transfer force can be improved.

When the magnetic flux density in the normal direction of the delivery magnetic pole is U Gauss, the magnetic flux density in the normal direction of the magnetic pole for reception is L Gauss, and the gap between the first and second developing rollers is X mm, Since LU−50 gauss and X ≦ 1.5 mm, the developer transfer force can be improved.

Accordingly, a magnetic force forming mechanism is provided in a plurality of developing devices, a hard developing roller having a narrow magnetic force space is used, and a gap in a very narrow space is maintained between the first and second developing rollers. Under the condition that an expensive gap maintaining mechanism is not provided, 100% transfer of the developer from the first developing roller to the second developing roller can be delivered without problems such as image quality deterioration, conveyance failure, and scattering. . Therefore, there is an effect that a high-performance and low-cost multiple developing device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a photoconductor and a developing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a magnetic pole arrangement configuration of a developing roller.

FIG. 3 is a diagram showing a magnetic pole arrangement of a conventional developing roller.

FIG. 4 is a schematic diagram illustrating a magnetic force pattern of the developing roller of FIG. 3;

FIG. 5 is a schematic diagram illustrating a magnetic force pattern of the developing roller of FIG. 2;

FIG. 6 is a diagram illustrating a magnetic pole arrangement configuration of a developing roller according to another embodiment of the present invention.

FIG. 7 is a diagram showing an area where the developer is well transferred between the developing rollers shown in FIG. 6;

FIG. 8 is a diagram illustrating a deflection of a magnetic pole arrangement of a developing roller in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum (image carrier) 5 ... 1st developing roller 6 ... 2nd developing roller 10, 11 ... Agitation conveying means 15 ... Conveying roller S1 ... Delivery magnetic pole S2 ... 1st peeling pole S3 ... No. 2 separation pole 22 ... First magnet N2 ... Receiving magnetic pole 24 ... Second magnet

Claims (8)

[Claims] And a first and second developing roller that conveys a developer by supplying the developer to the image carrier by rotating the same in the same direction. The first developing roller is fixedly provided in the first developing roller;
The developer over the second rotation direction of the developing roller.
A first magnet having a delivery magnetic pole for delivery to the developing roller and a first peeling pole for peeling the developer having the same polarity as the delivery magnetic pole; and And a second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole for receiving the developer delivered from the first developing roller, wherein the delivering magnet is provided on the first magnet. And at least one second peeling pole having the same polarity as the first peeling pole is provided between the first peeling pole and the first peeling pole. A first and a second developing roller which conveys a developer by supplying the developer to the image carrier by rotating the same in the same direction as the rotating image carrier; A stirring and conveying means for stirring and conveying the developer toward the first and second developing rollers; a conveying roller for conveying the developer stirred and conveyed by the stirring and conveying means to the first developing roller; A first developing roller fixedly provided in the first developing roller,
The developer over the second rotation direction of the developing roller.
A first magnet having a delivery magnetic pole for delivering to the developing roller and a first peeling pole for peeling the developer having the same polarity as the delivering magnetic pole, and a first magnet fixed to the second developing roller. A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole for receiving the developer delivered from the first developing roller, wherein the delivering magnetic pole is provided on the first magnet. A second peeling pole having the same polarity as the first peeling pole is provided between the magnetic pole for transfer and the first peeling pole. 3. A first and a second developing roller, which are arranged to face a rotating image carrier along the direction of rotation thereof and rotate in the same direction to convey a developer and supply the developer to the image carrier. A stirring and conveying means for stirring and conveying the developer toward the first and second developing rollers; a conveying roller for conveying the developer stirred and conveyed by the stirring and conveying means to the first developing roller; A first developing roller fixedly provided in the first developing roller,
The developer over the second rotation direction of the developing roller.
A first magnet having a delivery magnetic pole for delivery to the developing roller and a first peeling pole for peeling the developer having the same polarity as the delivery magnetic pole; and A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole for receiving the developer delivered from the first developing roller, wherein the delivering magnetic pole is provided on the first magnet. A second separation pole having the same polarity as the first separation pole is provided between the first separation pole and the first separation pole, and a first separation pole connecting the center of the first developing roller and the delivery magnetic pole is provided. A line segment, the center of the first developing roller and the second
The absolute value of the angle formed by the second line segment connecting the separation pole of
A developing device, wherein the second peeling pole is brought close to the delivery magnetic pole so as to be 5 ° or less. 4. A first and a second developing roller, which are arranged opposite to a rotating image carrier along a rotation direction thereof and rotate in the same direction to convey a developer and supply the developer to the image carrier. A delivery magnetic pole fixedly provided in the first developing roller, for delivering the developer to the second developing roller, and a delivery magnetic pole for peeling the developer with the same polarity as the delivery magnetic pole. A first magnet having one peeling pole, and a receiving magnet fixedly provided on the second developing roller and having a polarity opposite to that of the delivering magnetic pole for receiving a developer delivered from the first developing roller. A second magnet having magnetic poles, wherein U-Gauss is the magnetic flux density in the normal direction of the transfer magnetic pole and L Gauss is the magnetic flux density in the normal direction of the magnetic pole for reception. Gaussian developing device 5. A first and a second developing roller, which are arranged to face a rotating image carrier along a rotation direction thereof and rotate in the same direction to convey a developer and supply the developer to the image carrier. A delivery magnetic pole fixedly provided in the first developing roller, for delivering the developer to the second developing roller, and a delivery magnetic pole for peeling the developer with the same polarity as the delivery magnetic pole. A first magnet having one peeling pole, and a receiving magnet fixedly provided on the second developing roller and having a polarity opposite to that of the delivering magnetic pole for receiving a developer delivered from the first developing roller. A second magnet having a magnetic pole, wherein X ≦ 1.5 mm when a gap between the first and second developing rollers is X mm. 6. A first developing roller and a second developing roller which convey developer by supplying the developer to the image carrier by rotating the same in the same direction as the rotating image carrier. A delivery magnetic pole fixedly provided in the first developing roller, for delivering the developer to the second developing roller, and a delivery magnetic pole for peeling the developer with the same polarity as the delivery magnetic pole. A first magnet having one peeling pole, and a receiving magnet fixedly provided on the second developing roller and having a polarity opposite to that of the delivering magnetic pole for receiving a developer delivered from the first developing roller. A second magnet having a magnetic pole, wherein the magnetic flux density in the normal direction of the transfer magnetic pole is U gauss, the magnetic flux density in the normal direction of the magnetic pole for reception is L gauss,
And the gap between the second developing roller and Xmm,
A developing device, wherein LU ≧ 50 Gauss and X ≦ 1.5 mm. 7. A first developing roller and a second developing roller which convey a developer by supplying the developer to the image carrier by rotating the same in the same direction as the rotating image carrier. A stirring and conveying means for stirring and conveying the developer toward the first and second developing rollers; a conveying roller for conveying the developer stirred and conveyed by the stirring and conveying means to the first developing roller; A first developing roller fixedly provided in the first developing roller,
The developer over the second rotation direction of the developing roller.
A first magnet having a delivery magnetic pole for delivering to the developing roller and a first peeling pole for peeling the developer having the same polarity as the delivering magnetic pole, and a first magnet fixed to the second developing roller. A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole for receiving the developer delivered from the first developing roller, wherein the delivering magnetic pole is provided on the first magnet. A second separation pole having the same polarity as the first separation pole is provided between the first separation pole and the first separation pole; a magnetic flux density in a normal direction of the delivery magnetic pole is U Gauss; The magnetic flux density in the normal direction of L is Gauss,
And the gap between the second developing roller and Xmm,
A developing device, wherein LU ≧ 50 Gauss and X ≦ 1.5 mm. 8. A first and a second developing roller for conveying a developer and supplying the developer to the rotating image carrier by conveying the developer by rotating the same in the same direction. A stirring and conveying means for stirring and conveying the developer toward the first and second developing rollers; a conveying roller for conveying the developer stirred and conveyed by the stirring and conveying means to the first developing roller; A first developing roller fixedly provided in the first developing roller,
The developer over the second rotation direction of the developing roller.
A first magnet having a delivery magnetic pole for delivering to the developing roller and a first peeling pole for peeling the developer having the same polarity as the delivering magnetic pole, and a first magnet fixed to the second developing roller. A second magnet having a receiving magnetic pole having a polarity opposite to that of the delivering magnetic pole for receiving the developer delivered from the first developing roller, wherein the delivering magnetic pole is provided on the first magnet. A second separation pole having the same polarity as the first separation pole is provided between the first separation pole and the first separation pole, and a first separation pole connecting the center of the first developing roller and the delivery magnetic pole is provided. A line segment, the center of the first developing roller and the second
The absolute value of the angle formed by the second line segment connecting the separation pole of
The second separation pole is brought close to the delivery magnetic pole so as to be 5 ° or less, the magnetic flux density in the normal direction of the delivery magnetic pole is U Gauss, and the magnetic flux density in the normal direction of the reception magnetic pole is L. Gauss, the first
And the gap between the second developing roller and Xmm,
A developing device, wherein LU ≧ 50 Gauss and X ≦ 1.5 mm.