JP2000162875A - Developing roller and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing roller, capable of reducing penetration of developer into a pivotally supported section of the roller shaft of the developing roller, preventing the developer from creeping into the pivotally support section, and making a stable image formation possible regardless of the use over a long period, by smoothly performing the receipt and delivery of the developer between respective magnetic poles in a developing device. SOLUTION: This developing roller is, constituted of a developing sleeve, a fix-support member being incorporated in the developing sleeve provided with a plural of magnetic poles forming a magnetic field outside a developing sleeve, and the roller shaft which pivoltally supported at both end parts freely rotatably. In such a case, among the magnetization length in the longitudinal direction of fixed magnetic bodies Mn1, Mn2, Ms1, Ms2 and Ms3 feeding magnetic forces on plural magnetic poles N1, N2, S1, S2 and S3, the magnetization length of a fixed magnetic body Mn1 which apply the magnetic force on a magnetic pole N1 serving as the main developing pole, is set longer than the magnetization length of any of other magnetization lengths of fixed magnetic body Mn2, Ms1, Ms2 or Ms3 feeding the magnetic force on another developer transporting magnetic pole N2, S1, S2 or S3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer carrier for conveying a developer, which is used in a developing device such as a copying machine or a laser printer which is an image forming apparatus of an electrophotographic system, and a developer carrier for the developer. A plurality of magnetic poles that are included and form a magnetic field outside the developer carrier through the developer carrier, a plurality of fixed magnets that supply magnetic force to the magnetic poles, and the plurality of fixed magnets And a fixed support member for supporting the plurality of magnetic poles and a roller shaft rotatably supported at both ends.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus using an electrophotographic process, a developing apparatus using a two-component developer has been known.

Referring to FIG. 21, this conventional developing device will be described. A developing sleeve 3 which is a cylindrical developer carrier made of a non-magnetic material is fixed in a developing tank 2 of a developing device main body 1 by a fixed magnet which is a fixed magnet. The developing tank 2 includes a magnet and is rotatably disposed around the fixed magnet.
A supply roller 4 for supplying the two-component developer therein is provided, and a stirring and supply roller 5 for stirring the two-component developer supplied by the supply roller 4 and supplying it to the developing sleeve 3 is provided.

The developing sleeve 3 carries the two-component developer supplied by the stirring supply roller 5, and the layer thickness of the carried two-component developer is regulated by a developing blade which is a developer layer thickness regulating member. After being formed to a predetermined layer thickness, it is conveyed to a developing section, where it is used for developing an electrostatic latent image formed on a photosensitive drum 6 as an electrostatic latent image carrier.

At the time of development, a developing bias in which an AC voltage is superimposed on a DC voltage is applied between the developing sleeve 3 and the photosensitive drum 6 to perform development, and the electrostatic latent image on the photosensitive drum 6 is visualized as a toner image. Is done.

[0006]

However, in the above-mentioned conventional structure, the magnet used for the fixed magnet is cylindrical and each pole is magnetized to the end, so that the developer is rotated with the rotation of the developing roller. Both ends of the developing roller,
That is, it wraps around and stays at the shaft support portion of the roller shaft,
Since the developer continues to flow into this portion, the density of the developer becomes relatively high.

Therefore, by continuously using the developing device, the intrusion of the toner into the shaft supporting portion of the developing roller gradually progresses, and the developer is fused due to an increase in rotational torque and heat generation, and the roller shaft is fixed to the shaft. There was a problem of doing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and has an advantage that the developer can be smoothly transferred between the magnetic poles in the developing device, and the developer can be circulated satisfactorily. An object of the present invention is to provide a developing roller that reduces the amount of developer flowing around a shaft support portion, prevents the developer from entering the shaft support portion, and enables stable image formation even during long-term use. Things.

[0009]

In order to achieve the above object, the invention according to claim 1 is used in a developing device of an electrophotographic image forming apparatus, and a developer carrier for transporting a developer; A plurality of magnetic poles that are included in the developer carrier and form a magnetic field outside the developer carrier via the developer carrier, a plurality of fixed magnet bodies that supply magnetic force to the magnetic poles, In a developing roller including a plurality of fixed magnet bodies and a fixed support member supporting the plurality of magnetic poles, and a roller shaft rotatably supported at both ends, a magnetic force is applied to the plurality of magnetic poles. Of the longitudinal magnetized length of the fixed magnet body to be supplied, the magnetized length of the fixed magnet body that supplies the magnetic force to the magnetic pole serving as the main development pole is determined by the magnetized length of the fixed magnet body that supplies the magnetic force to the other developer carrying magnetic poles. It is set longer than the magnetic length.

The invention according to claim 2 is used in a developing device of an electrophotographic image forming apparatus, and includes a developer carrier for transporting a developer and the developer carrier which is included in the developer carrier. A plurality of magnetic poles that form a magnetic field outside the developer carrier via the plurality of fixed magnetic bodies that supply a magnetic force to the magnetic poles; and the plurality of fixed magnet bodies and the plurality of magnetic poles. In a developing roller composed of a fixed support member for supporting and a roller shaft rotatably supported at both ends,
Of the longitudinal magnetized length of the fixed magnet body that supplies the magnetic force to the plurality of magnetic poles, the magnetized length of the fixed magnet body that supplies the magnetic force to the magnetic pole serving as the recovery pole located downstream of the developing main pole, The length is set shorter than the magnetization length of the fixed magnet body that supplies the magnetic force to the magnetic pole serving as the development main pole.

According to a third aspect of the present invention, the developer by the developing roller is determined by the magnetized length of the fixed magnet that supplies the magnetic force to the magnetic pole immediately downstream of the magnetic pole serving as the main developing pole. The magnetization length of the fixed magnet body that supplies magnetic force to the magnetic pole located at the most downstream of the transport flow is set short.

According to a fourth aspect of the present invention, the developer by the developing roller is determined based on the magnetization length of the fixed magnet body that supplies a magnetic force to the magnetic pole immediately after the developing main pole upstream of the magnetic pole serving as the main developing pole. The magnetization length of the fixed magnet body that supplies magnetic force to the magnetic pole located at the uppermost stream of the transport flow is set short.

According to a fifth aspect of the present invention, both ends of a fixed magnet body for supplying a magnetic force to each magnetic pole set shorter than the magnetic pole serving as the main developing pole are successively moved away from the magnetic pole serving as the main developing pole. It is formed to be shorter.

According to a sixth aspect of the present invention, there is provided a developer carrier for transporting a developer, and a magnetic field formed outside the developer carrier via the developer carrier by being included in the developer carrier. A plurality of magnetic poles, a plurality of fixed magnets for supplying magnetic force to the magnetic poles, a fixed support member for supporting the plurality of fixed magnets and the plurality of magnetic poles, and a rotatable shaft at both ends. A developing roller composed of a supported roller shaft, and a longitudinal magnetized length of a fixed magnet body that supplies a magnetic force to a plurality of magnetic poles of the developing roller, which is set according to the rotation speed of the developing roller. I have.

According to a seventh aspect of the present invention, there is provided a developer carrying member for transporting a developer, and a magnetic field formed outside the developer carrying member via the developer carrying member. A plurality of magnetic poles, a plurality of fixed magnets for supplying magnetic force to the magnetic poles, a fixed support member for supporting the plurality of fixed magnets and the plurality of magnetic poles, and a rotatable shaft at both ends. A developing roller having a developing roller composed of a roller shaft supported by the developing roller, wherein a magnetic pole serving as a main developing pole is selected from among longitudinal magnetized lengths of a fixed magnet body for supplying magnetic force to a plurality of magnetic poles of the developing roller. The magnetized length of the fixed magnet body that supplies magnetic force to the developer is set longer than the magnetized length of the fixed magnet body that supplies magnetic force to the other developer carrying magnetic poles.

According to the present invention, a developer layer thickness regulating member for regulating the layer thickness of the developer carried by the developer carrier is provided, and the length of the developer layer thickness regulating member in the longitudinal direction is adjusted. The length is set shorter than the length of the fixed magnet body in the longitudinal direction.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the developing roller of the present invention will be described with reference to the drawings. The structure of the developing device using this developing roller is basically the same as that of FIG.

Embodiment 1 of the developing roller of the present invention will be described with reference to FIG. FIG. 1 shows a plurality of fixed magnets included in a developing sleeve and a developing main pole N1 corresponding to a developing position.
FIG. In the developing roller of the first embodiment, the magnetization length of the fixed magnet Mn1 that supplies the magnetic force to the developing main pole N1 is different from that of the other magnetic poles S1, S2, S3, N
Fixed magnets Ms1, Ms2, M for supplying magnetic force to
It is set longer than the magnetization length of s3, Mn2.

As described above, since the magnetization lengths of the other magnetic poles S1, S2, S3 and N2 of the developing main pole N1 of the developing roller are short,
The magnetic force acting on both ends of the developing roller is small, the flow of the developer in the portions other than the developing main pole N1 of the developing roller at both ends is reduced, and the wraparound of the developer to the end surface of the developing roller is reduced, The intrusion of the developer into the shaft support portion of the roller shaft of the developing roller is prevented, and it is possible to prevent the rotation shaft from increasing due to long-term use and the shaft sticking of the roller shaft caused by the fusion of the developer due to heat generation.

Embodiment 2 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the second embodiment, the collecting pole (release pole, release pole or peeling pole) located downstream of the main developing pole N1 with respect to the magnetization length of the fixed magnet Mn1 that supplies magnetic force to the main developing pole N1. Fixed magnet Ms for supplying magnetic force to the magnetic poles S2 and S3 to be referred to as
2 and Ms3 are set to be short.

This is because the upstream side of the main developing electrode N1 is a side for discharging the developer, while the downstream side of the main developing electrode N1 is a side for collecting the developing agent. The balance of is that the transport amount of the developer on the downstream side is larger than the transport amount of the developer on the upstream side, so that the magnetization length of the magnetic poles S2 and S3 on the downstream side of the developing main pole N1 of the developing roller is shortened. As a result, the magnetic force acting on both ends of the developing roller downstream of the developing main pole N1 is small, the flow of the developer at these ends is reduced, and the downstream side of the developing main pole N1 with a large transport amount of the developer is reduced. The amount of developer flowing around the end surface of the developing roller is reduced, preventing the developer from entering the shaft support of the roller shaft of the developing roller. The developer is fused due to an increase in rotational torque and heat generation due to long-term use. Can be prevented from sticking to the roller shaft.

Embodiment 3 of the developing roller of the present invention will be described with reference to FIG. In the developing roller according to the third embodiment, the developing main pole N1 is located on the downstream side of the main developing pole N1 with respect to the magnetization length of the fixed magnet Mn1 that supplies magnetic force to the main developing pole N1.
The magnetized length of the fixed magnet Ms2 that supplies a magnetic force to the magnetic pole S2 serving as the recovery pole located immediately after the magnetic pole S2 is set to be short, and the magnetic pole S3 located downstream of the magnetic pole S2 (most downstream from the development main pole N1). Magnet Ms to supply magnetic force to
The magnetizing length of No. 3 is set shorter than the fixed magnet Ms2 of the magnetic pole S2.

Embodiment 4 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the fourth embodiment, the magnetization length of the fixed magnet Mn1 of the developing main pole N1 is changed to the fixed magnets Ms1 and Ms of the other magnetic poles S1, S2, S3 and N2.
2, Ms3, Mn2, and is set longer than
The magnetic pole S3, which is located downstream of the fixed length of the fixed magnet Ms2 of the magnetic pole S2 (collection pole) located immediately downstream of the developing main pole N1 and downstream of the developing main pole N1 (most downstream from the developing main pole N1).
Is set shorter than the fixed magnet Ms2 of the magnetic pole S2.

As in the third and fourth embodiments,
By setting the magnetization lengths of the fixed magnets Ms2 and Ms3 of the magnetic poles S2 and S3 on the downstream side of the development main pole N1 to be shorter in order, the developer can flow in a stable state and be smoothly collected into the developing tank. it can.

Embodiment 5 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the fifth embodiment, the magnetization length of the fixed magnet Mn1 of the developing main pole N1 is changed to the fixed magnets Ms1 and Ms of the other magnetic poles S1, S2, S3 and N2.
2, Ms3, Mn2, and is set longer than
The magnetic pole N2 located upstream of the magnetization length of the fixed magnet Ms1 of the magnetic pole S1 serving as a recovery pole located immediately upstream of the main development pole N1 (the most upstream side from the main development pole N1).
Is set shorter than the fixed magnet Ms1 of the magnetic pole S1.

As in the fifth embodiment, the fixed magnets Ms1 and Mn of the magnetic poles S1 and N2 on the upstream side of the developing main pole N1.
By setting the magnetization length of No. 2 in order, the developer can flow in a stable state and can be smoothly supplied to the main development pole N1.

Embodiment 6 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the sixth embodiment, the fixed magnets of the magnetic poles S2 and S1 located immediately downstream of the developing main pole N1 on the downstream and upstream sides of the developing main pole N1 with respect to the magnetization length of the fixed magnet Mn1 of the developing main pole N1. Ms2, Ms1
Downstream from the magnetized length (most downstream from the developing main pole N1)
The magnetized length of the fixed magnet Ms3 of the magnetic pole S3 and the fixed magnet Mn2 of the magnetic pole N2 located on the upstream side (the most upstream side from the developing main pole N1) is set shorter than the fixed magnets Ms2 and Ms1 of the magnetic poles S2 and S1. .

As in the sixth embodiment, the fixed magnets Ms2 and Ms2 of the magnetic poles S2 and S3 on the downstream side of the developing main pole N1.
By sequentially shortening the magnetization length of No. 3, the developer can flow in a stable state and be smoothly collected inside the developing tank, and the magnetic pole S upstream of the main developing pole N1 can be collected.
By sequentially setting the magnetization lengths of the fixed magnets Ms1 and Mn2 of N1 and N2 to be shorter, the developer can flow in a stable state and can be smoothly supplied to the main development pole N1.

Embodiment 7 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the seventh embodiment, the magnetization length of the fixed magnet Mn1 of the developing main pole N1 is changed to the fixed magnets Ms1 and Ms of the other magnetic poles S1, S2, S3 and N2.
2, Ms3, Mn2, and is set longer than
The magnetic pole S3, which is located downstream of the fixed length of the fixed magnet Ms2 of the magnetic pole S2 (collection pole) located immediately downstream of the developing main pole N1 and downstream of the developing main pole N1 (most downstream from the developing main pole N1).
Is set shorter than the fixed magnet Ms2 of the magnetic pole S2. The fixed magnets Ms2 and Ms that supply magnetic force to the magnetic poles S2 and S3.
3 are formed such that both ends are gradually shortened in a direction away from the developing main pole N1.

Embodiment 8 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the eighth embodiment, the magnetization length of the fixed magnet Ms2 of the magnetic pole S2 located downstream of the magnetization length of the fixed magnet Mn1 of the main development pole N1 and immediately after the main development pole N1 is set shorter. The magnetization length of the fixed magnet Ms3 of the magnetic pole S3 located downstream of the fixed magnet Ms2 of the magnetic pole S2 (the most downstream side from the developing main pole N1) is set shorter than the fixed magnet Ms2 of the magnetic pole S2. Then, both ends of the fixed magnet bodies Ms2 and Ms3 for supplying a magnetic force to the magnetic poles S2 and S3 are connected to the developing main pole N1.
It is formed so as to be gradually shortened in a direction away from the object.

As in the seventh and eighth embodiments,
The magnetized lengths of the fixed magnets Ms2 and Ms3 of the magnetic poles S2 and S3 on the downstream side of the development main pole N1 are set to be short in order, and both ends of each of the fixed magnets Ms2 and Ms3 are sequentially shortened, so that the fixed magnets Ms2 and Ms3 are formed. As the both ends of the magnetization length gradually become shorter, the flow width of the developer gradually narrows along the flow direction of the developer, and the developer flows in a more stable state and smoothly enters the developing tank. Can be recovered.

Embodiment 9 of the developing roller of the present invention will be described with reference to FIG. In the developing roller of the ninth embodiment, the magnetization length of the fixed magnet Mn1 of the developing main pole N1 is changed to the fixed magnets Ms1 and Ms of the other magnetic poles S1, S2, S3 and N2.
2, Ms3, Mn2, and is set longer than
The magnetic pole N2 located upstream of the magnetization length of the fixed magnet Ms1 of the magnetic pole S1 serving as a recovery pole located immediately upstream of the main development pole N1 (the most upstream side from the main development pole N1).
Is set shorter than the fixed magnet Ms1 of the magnetic pole S1. The fixed magnets Ms1, Mn that supply magnetic force to the magnetic poles S1, N2.
1 are formed so as to be successively shorter in a direction away from the main developing pole N1.

Embodiment 10 of the developing roller of the present invention is shown in FIG.
It will be described together with 0. In the developing roller of the tenth embodiment, the fixed magnets Ms2 and Ms of the magnetic poles S2 and S3 on the downstream side of the magnetization length of the fixed magnet Mn1 of the developing main pole N1.
3 is set to be short, and the fixed magnet M of the magnetic pole S1 immediately after the upstream of the fixed magnet Mn1 of the developing main pole N1 is set.
The both ends of s1 are sequentially shortened in a direction away from the main development pole N1, and the fixed magnet Mn2 of the magnetic pole N2 downstream of the fixed magnet Ms1 of the magnetic pole S1 is fixed to the fixed magnet M
It is set shorter than s1, and both ends of the fixed magnet Mn2 of the magnetic pole N2 are formed sequentially shorter in a direction away from the main developing pole N1.

As in the ninth and tenth embodiments, both ends of the fixed magnets Ms1 and Mn2 of the magnetic poles S1 and N2 on the upstream side of the developing main pole N1 are sequentially shortened, so that each fixed magnet Ms1 and Mn2 is By gradually shortening both ends of the magnetization length, the flow width of the developer gradually narrows along the flow direction of the developer, so that the developer flows in a more stable state and is supplied to the developing unit smoothly. be able to.

Embodiment 11 of the developing roller of the present invention is shown in FIG.
It will be described together with 1. In the developing roller of the eleventh embodiment, the magnetization length of the fixed magnet Mn1 of the developing main pole N1 is changed to the fixed magnet Ms of the other magnetic poles S1, S2, S3, and N2.
1, Ms2, Ms3, Mn2, and the fixed magnets S2, S3 downstream of the developing main pole N1 and the fixed magnets S1, N2 upstream thereof are sequentially set shorter. S1, N2
Are sequentially shortened in a direction away from the main development pole N1.

Embodiment 12 of the developing roller of the present invention is shown in FIG.
It will be described together with 2. In the developing roller of the twelfth embodiment, the fixed magnets Ms of the magnetic poles S2 and S1 immediately downstream and upstream of the fixed magnet Mn1 of the main developing pole N1.
2, Ms1 are formed to be shorter in the direction away from the main developing pole N1, and the fixed magnets M of the magnetic poles S2, S1 are formed.
The fixed magnets Ms3 and Mn2 of the magnetic poles S3 and N2 on the downstream and upstream sides of s2 and Ms1 are replaced with the fixed magnets Ms2 and Ms2.
Ms1 is shorter than Ms1, and both ends of the fixed magnets Ms3 and Mn2 of the magnetic poles S3 and N2 are sequentially shortened in a direction away from the development main pole N1.

As in the eleventh and twelfth embodiments, the magnetic poles S2 and S3 on the downstream side and the upstream side of the developing main pole N1 are used.
By forming both ends of the fixed magnets S2 and S3 and the fixed magnets Ms1 and Mn2 of the magnetic poles S1 and N2 sequentially shorter, both ends of the magnetization length of each of the fixed magnets Ms2 and Ms3 and the fixed magnets Ms1 and Mn2 gradually become shorter. In particular, the flow width of the developer gradually decreases along the flow direction of the developer, and the developer can flow in a more stable state, and the developer can be smoothly collected inside the developing tank. The developer can be smoothly supplied in a stable state by the developing unit.

In the first to twelfth embodiments, the developing roller is constituted by five magnetic poles.
If the number of magnetic poles is an odd number, such as a developing roller composed of three magnetic poles shown in FIG. 3 or a developing roller composed of seven magnetic poles shown in FIG.
The same effect as that of the developing roller having the magnetic pole can be obtained. FIG. 15 shows an example of the arrangement of the magnetic poles in the case where the developing roller is constituted by five magnetic poles, and FIG. 16 shows the example of the arrangement of the magnetic poles in the case where the developing roller is constituted by seven magnetic poles.

Embodiment 1, Embodiment 6, Embodiment 1
1, in the developing device using the developing roller of the twelfth embodiment, and in the developing device using the developing roller of Comparative Example 2 and Comparative Example 2, whether or not the developer has entered the shaft support portion of the roller shaft; Tables 1 and 2 show changes in the rotational torque.

In Comparative Example 1, as shown in FIG. 17, the fixed magnets Mn of all the magnetic poles N1, N2, S1, S2, and S3 were used.
1, Mn2, Ms1, Ms2, and Ms3 were set to the same magnetization length. In Comparative Example 2, as shown in FIG. 18, the magnetization length of the fixed magnet Mn1 of the development main pole N1 was changed to that of another fixed magnet. It is set shorter than the magnetization lengths of Mn2, Ms1, Ms2, and Ms3.

[0041]

[Table 1]

[0042]

[Table 2]

First, as shown in Table 1, in each of the developing devices, when the idling time reaches 100 (h), in the comparative examples 1 and 2, the developer is applied to the shaft supporting portion of the roller shaft. Intrusion is observed, and when 400 (h) is reached, the first embodiment
In this case, the developer enters the shaft supporting portion of the roller shaft, and at 500 (h), in the second embodiment, the developer enters the shaft supporting portion of the roller shaft. Thus, in the eleventh and twelfth embodiments, 500
Even after elapse of (h), there is no intrusion of the developer into the roller shaft, and good operation is possible even in long-term use.

Further, as shown in Table 2, when the idling time exceeds 300 (h) in each developing device, in Comparative Examples 1 and 2, the rotational torque is much larger than the initial rotational torque. However, in the first and sixth embodiments, although the rotation torque slightly increases after 500 (h), the magnitude of the rotation torque is within an allowable range. In the case of the eleventh and twelfth embodiments, the magnitude of the initial rotational torque hardly changed even if it exceeded 500 (h).

Embodiment 15 of the developing apparatus using the developing roller of the present invention will be described with reference to FIG. FIG. 19 is a developed view showing a relationship between a magnetic pole obtained by developing a plurality of fixed magnets included in a developing sleeve around a main developing pole N1 corresponding to a developing position and a developer layer thickness regulating member (developer regulating member). It is. In the developing roller of the fifteenth embodiment, the magnetization length of the fixed magnet Mn1 of the developing main pole N1 is changed to the other magnetic poles S1,
Fixed magnets Ms1, Ms2, M of S2, S3, N2
It is set longer than s3, Mn2, and the length in the longitudinal direction of the developer layer thickness regulating member (developer regulating member) is set shorter than the magnetization length of the fixed magnets Ms1, Ms2, Ms3, Mn2.

Embodiment 16 of the developing apparatus using the developing roller of the present invention will be described with reference to FIG. Embodiment 1
5, the fixed magnet M of the developing main pole N1
The magnetized lengths of the fixed magnets Ms1 and Ms2 of the other magnetic poles S1 and S2 are set shorter than the magnetized length of n1. The fixed magnets Mn2 and Ms3 of the other magnetic poles N2 and S3 are smaller than the magnetized lengths of the fixed magnets Ms1 and Ms2. Set the magnetization length of
The length of the developer layer thickness regulating member (developer regulating member) in the longitudinal direction is set to the fixed magnets Mn2 and Ms of the other magnetic poles N2 and S3.
The magnetization length of No. 3 is set short.

As in Embodiments 14 and 15, the length of the developer layer thickness regulating member (developer regulating member) in the longitudinal direction is set shorter than the other magnetic poles. Even if the surplus developer regulated by the developer layer thickness regulating member (developer regulating member) goes around both ends of the developer layer thickness regulating member (developer regulating member), the excess developer Is prevented from reaching the both ends of the developing sleeve due to the magnetic poles of the developing sleeve, so that the roller shaft is reliably prevented from entering the shaft support portion.

A seventeenth embodiment of the developing device using the developing roller of the present invention will be described.

In the developing device of the seventeenth embodiment, the fixed magnets Ms1, Ms2,
The magnetization length of Ms3, Mn1, Mn2 is set. This is because when the rotation speed of the developing roller rises above the reference rotation speed, the developer gathers at the central portion in the axial direction, so that the magnetization length extending to both ends may be set short. Further, when the rotation speed of the developing roller is lower than the reference rotation speed, the developer spreads so as to flow to both ends in the axial direction. Is set to be longer.

For example, a developing device designed as a developing device of an image forming apparatus capable of copying a certain number of copies (printing) per minute can be set to a certain number of times later due to an increase in model variations of the image forming apparatus. Applied and mounted on high-speed machines (models with more than the set number of copies that can be copied) or low-speed machines (models with a set number of copies that are smaller than the number of copies that can be made) When the developing casing (developing roller) of the developing device of the base model is commonly used for each model, that is, when the developing casing is used as a common component between the respective models, the diameter of the developing roller (developing sleeve)・ Length etc. are designed with the same specifications, and only fixed magnets that apply magnetic force to the developing sleeve are compatible with the model type (high-speed machine, base machine, low-speed machine). Change used by, in the case of so rationalize design and production, in the case to be mounted on a high-speed high-speed machines than the image forming apparatus as a base machine,
When the developing roller is used at a higher rotation speed than the rotation speed of the developing roller set on the base machine, and is mounted on a low-speed machine that is slower than the image forming apparatus serving as the base machine, the developing roller set on the base machine is used. The developing roller is used at a lower rotation speed than the rotation speed.

More specifically, when a set number of sheets is first set as the number of copies that can be made for the base model, the process speed (peripheral speed of the photoconductor) is determined accordingly, and the electrostatic latent on the photoconductor surface is determined. The peripheral speed of the developing sleeve is determined so that the developer can be supplied to the image without excess or shortage. The peripheral speed of the developing sleeve is set to a rotation speed (for example, 200 rpm) which has a peripheral speed of about 2 to 3 times the normal process speed, and the magnetization length at this time is set to 227 mm.

When the developing device used for the model whose base is set in such a manner as described above is applied to a high-speed machine, the peripheral speed of the photosensitive member increases in accordance with the number of copies that can be made. The peripheral speed of the roller (developing sleeve) also increases and is set to, for example, 220 rpm. Since the developer gathers at the center of the developing sleeve due to the increase in the peripheral speed of the developing roller, the magnetization length of the developing sleeve is set to 220 mm as shown in Table 3 according to the increase in the peripheral speed of the developing roller.

Further, when the developing device used for the base model whose rotation speed is set as described above is applied to a low-speed machine, the peripheral speed of the photosensitive member becomes lower in accordance with the number of copies that can be made. The peripheral speed of the developing roller (developing sleeve) is also reduced, and is set to, for example, 180 rpm. Since the developer spreads to both ends of the developing sleeve due to the decrease in the peripheral speed of the developing roller, as shown in Table 3, the developer spreads in accordance with the decrease in the peripheral speed of the developing roller to receive the spread developer. The magnetic length is set to 233 mm.

[0054]

[Table 3]

As described above, the behavior of the developer changes with the change of the rotation speed (peripheral speed) of the developing sleeve corresponding to the change of the process speed by applying to the high-speed machine or the low-speed machine from the base model. This change can be dealt with by changing the magnetization length of the developing sleeve, eliminating inconveniences such as leakage of developer due to the change in the behavior of the developer. Applicable to

[0056]

According to the first and second aspects of the present invention, it is possible to suppress the inflow and stagnation of the developer into the shaft support portion of the roller shaft at both ends of the developing roller, and to perform the development on the shaft support portion. As the developer flows in, the density of the developer increases, and the developer enters the shaft portion of the roller shaft, thereby preventing the rotation torque of the developing roller from increasing and generating heat, and fixing the roller shaft by fusing the developer. , And stable image formation can be performed for a long period of time.

According to a third aspect of the present invention, the developer is conveyed by the developing roller based on the magnetization length of the fixed magnet which supplies the magnetic force to the magnetic pole immediately downstream of the magnetic pole which is the main developing pole. By setting the magnetization length of the fixed magnet body that supplies magnetic force to the magnetic pole located at the most downstream of the flow, the developer can flow smoothly, and the developer can be collected reliably and smoothly. Can be.

According to a fourth aspect of the present invention, the developer is conveyed by the developing roller based on the magnetization length of the fixed magnet that supplies the magnetic force to the magnetic pole immediately after the magnetic pole that is the upstream of the magnetic pole that is the main developing pole. By setting the magnetization length of the fixed magnet body that supplies magnetic force to the magnetic pole located at the uppermost stream of the flow to be short, the flow of the developer can be performed smoothly, and the supply of the developer to the main developing pole is ensured. It can be performed smoothly.

According to a fifth aspect of the present invention, both ends of the fixed magnet body that supplies magnetic force to each magnetic pole set shorter than the magnetic pole serving as the main developing pole are successively shortened in a direction away from the magnetic pole serving as the main developing pole. With such a configuration, the flow of the developer can be performed more smoothly, and the stagnation of the developer can be prevented.

According to a sixth aspect of the present invention, there is provided the developing roller, wherein the longitudinal magnetization length of the fixed magnet for supplying a magnetic force to the plurality of magnetic poles of the developing roller is set in accordance with the rotation speed of the developing roller. It is possible to cope with a change in the flow of the developer due to the number of rotations, and it is possible to reliably prevent the developer from flowing into the shaft support of the developing roller.

According to a seventh aspect of the present invention, of the fixed magnet body that supplies magnetic force to a plurality of magnetic poles of the developing roller, of the fixed magnet body that supplies magnetic force to the magnetic pole serving as the main development pole, of the longitudinal magnetized length. By setting the magnetization length to be longer than the magnetization length of the fixed magnet body that supplies the magnetic force to the other developer carrying magnetic poles, the developer flows into the shaft support portions of the roller shaft at both ends of the developing roller and The stagnation can be suppressed, the developer flows into the shaft support portion and the developer density increases, and the developer enters the shaft support portion of the roller shaft to prevent an increase in the rotational torque of the developing roller and heat generation. Thus, the fixing of the roller shaft due to the fusion of the developer is reliably prevented, and stable image formation can be performed for a long period of time.

According to the present invention, the length of the developer layer thickness regulating member in the longitudinal direction is set shorter than the length of the fixed magnet body in the longitudinal direction. Excess developer circulates inside the developing device without stagnation by stagnation around the roller shafts at both ends of the developing roller, ensuring a smooth and continuous supply of developer even after long-term use. However, it is possible to suppress an increase in rotation torque and heat generation due to the intrusion of the developer into the shaft support portion, and it is possible to improve the durability of the developing device.

[Brief description of the drawings]

FIG. 1 is a development view showing a development roller according to a first embodiment of the present invention, which is developed around a main development pole.

FIG. 2 is a development view illustrating a development roller according to a second embodiment of the invention, which is developed around a main development pole.

FIG. 3 is a development view illustrating a development roller according to a third embodiment of the invention, which is developed around a main development pole.

FIG. 4 is a development view illustrating a development roller according to a fourth embodiment of the present invention, which is developed around a main development pole.

FIG. 5 is a development view illustrating a development roller according to a fifth embodiment of the present invention, which is developed around a development main pole.

FIG. 6 is a development view illustrating a development roller according to a sixth embodiment of the invention, which is developed around a main development pole.

FIG. 7 is a development view illustrating a development roller according to a seventh embodiment of the invention, which is developed around a main development pole.

FIG. 8 is a development view illustrating a development roller according to an eighth embodiment of the present invention, which is developed around a main development pole.

FIG. 9 is a development view illustrating a development roller according to a ninth embodiment of the invention, which is developed with a development main pole as a center.

FIG. 10 is a development view illustrating a development roller according to a tenth embodiment of the invention, which is developed around a main development pole.

FIG. 11 is a development view showing a development roller according to an eleventh embodiment of the present invention, which is developed around a main development pole.

FIG. 12 is a development view illustrating a development roller according to a twelfth embodiment of the invention, which is developed around a main development pole.

FIG. 13 is a developed view showing a developing roller using three magnetic poles in the developing roller of the present invention.

FIG. 14 is a development view showing a developing roller of the present invention using seven magnetic poles.

FIG. 15 is a development view showing an example of magnetic pole arrangement in a developing roller of the present invention using three magnetic poles.

FIG. 16 is a development view showing an example of magnetic pole arrangement in a developing roller of the present invention using seven magnetic poles.

FIG. 17 is a developed view showing a state where the developing roller of the present invention is developed around a developing main pole of Comparative Example 1;

FIG. 18 is a developed view showing a state where the developing roller of the present invention is developed around a developing main pole of Comparative Example 2;

FIG. 19 is a developed view showing a relationship between a magnetic pole developed around a main developing pole and a developer layer thickness regulating member of a thirteenth embodiment using a developing roller of the present invention.

FIG. 20 is a developed view showing a relationship between a magnetic pole developed around a main developing pole and a developer layer thickness regulating member of a fourteenth embodiment using a developing roller of the present invention.

FIG. 21 is a schematic sectional view showing a developing device using a conventional developing roller.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Developing device main body 2 Developing tank 3 Developing sleeve 4 Supply roller 5 Stirring supply roller 6 Developing blade 7 Photoconductor drum N1 Developing main pole N2, S1, S2, S3 Magnetic pole Mn1, Mn2, Ms1, Ms2, Ms3 Fixed magnet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Kubota 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Yu Wakabayashi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Incorporated (72) Inventor Europe 22--22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Hisashi Kunihiro 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation F Terms (reference) 2H031 AC08 AC15 AC18 AC19 AC30 2H077 AD02 AD06 AD13 3J103 AA02 AA14 BA46 CA01 FA07 FA12 GA02 GA57 GA58

Claims (8)

[Claims] 1. A developer carrier used for a developing device of an electrophotographic image forming apparatus, which conveys a developer, a developer carrier included in the developer carrier, and a developer carrier via the developer carrier. A plurality of magnetic poles for forming a magnetic field outside the body, a plurality of fixed magnets for supplying a magnetic force to the magnetic poles, a fixed support member for supporting the plurality of fixed magnets and the plurality of magnetic poles And a roller shaft rotatably supported at both ends thereof, wherein a magnetic pole serving as a main developing pole among longitudinally magnetized lengths of a fixed magnet body for supplying magnetic force to the plurality of magnetic poles A magnetizing length of the fixed magnet body for supplying magnetic force to the other developer conveying magnetic pole is set longer than a magnetizing length of the fixed magnet body for supplying magnetic force to other developer carrying magnetic poles. 2. A developer carrying member used for a developing device of an electrophotographic image forming apparatus for transporting a developer, the developer carrying member being included in the developer carrying member, and carrying the developer through the developer carrying member. A plurality of magnetic poles for forming a magnetic field outside the body, a plurality of fixed magnets for supplying a magnetic force to the magnetic poles, a fixed support member for supporting the plurality of fixed magnets and the plurality of magnetic poles A roller shaft rotatably supported at both ends by a roller shaft, wherein, of the longitudinally magnetized length of the fixed magnet body that supplies magnetic force to the plurality of magnetic poles, the downstream side of the main developing pole. The magnetized length of the fixed magnet body that supplies magnetic force to the magnetic pole that is the recovery pole located at a position set to be shorter than the magnetized length of the fixed magnet body that supplies magnetic force to the magnetic pole that is the developing main pole. Developing roller. 3. The downstream side of the magnetic pole serving as the developing main pole, the most downstream of the developer conveying flow by the developing roller, from the magnetization length of the fixed magnet body that supplies magnetic force to the magnetic pole immediately after the main developing pole. The developing roller according to claim 1, wherein a magnetization length of a fixed magnet body that supplies a magnetic force to a located magnetic pole is set to be short. 4. The upstream of the magnetic pole serving as the main developing pole, the magnetizing length of the fixed magnet body that supplies magnetic force to the magnetic pole immediately after the main developing pole, the most upstream of the developer conveying flow by the developing roller. The developing roller according to claim 1, wherein a magnetization length of a fixed magnet body that supplies a magnetic force to a located magnetic pole is set to be short. 5. Both ends of a fixed magnet body for supplying a magnetic force to each magnetic pole set shorter than the magnetic pole serving as the main developing pole are formed so as to be successively shorter in a direction away from the magnetic pole serving as the main developing pole. The developing roller according to claim 3, wherein the developing roller is provided. 6. A developer carrier for transporting a developer, a plurality of magnetic poles included in the developer carrier and forming a magnetic field outside the developer carrier via the developer carrier, A plurality of fixed magnet bodies for supplying magnetic force to the magnetic poles, a fixed support member for supporting the plurality of fixed magnet bodies and the plurality of magnetic poles, and a roller shaft rotatably supported at both ends. In the developing device provided with a developing roller consisting of, the longitudinal magnetization length of the fixed magnet body that supplies magnetic force to a plurality of magnetic poles of the developing roller, is set according to the rotation speed of the developing roller. Characteristic developing device. 7. A developer carrier for transporting a developer, a plurality of magnetic poles included in the developer carrier, and forming a magnetic field outside the developer carrier via the developer carrier, A plurality of fixed magnet bodies for supplying magnetic force to the magnetic poles, a fixed support member for supporting the plurality of fixed magnet bodies and the plurality of magnetic poles, and a roller shaft rotatably supported at both ends. A developing roller comprising a developing roller comprising: a magnetic roller that supplies a magnetic force to a magnetic pole serving as a main developing pole of a longitudinal magnetized length of a fixed magnet body that supplies a magnetic force to a plurality of magnetic poles of the developing roller; A developing device wherein the magnetized length of the magnet body is set longer than the magnetized length of the fixed magnet body that supplies magnetic force to other developer carrying magnetic poles. 8. A developer layer thickness regulating member for regulating a layer thickness of a developer carried by the developer carrier, wherein a length of the developer layer thickness regulating member in a longitudinal direction is set to a length of the fixed magnet body. 8. The developing device according to claim 7, wherein the length is set shorter than the direction magnetization length.