JPH086398A - Developing device - Google Patents

Abstract

PURPOSE:To miniaturize a device, reduce the cost, prevent the generation of image noise due to the vibration at the time of rotation, prevent the deterioration of a developer when the quantity of the developer is regulated on a developing sleeve, and stably form a good image over a long period in a developing device feeding the toner in the developer to an image carrier from the developing sleeve for development. CONSTITUTION:This developing device is provided with a magnet member 22 having multiple magnetic poles on the inner periphery side of a developing sleeve 21. The outer periphery of the developing sleeve 21 is provided with a developer stir section 24 stirring a developer 1, a regulation section 25 regulating the quantity of the developer 1 on the developing sleeve 21, and a toner supply section 23 supplying a toner 1a to the developer 1 on the developing sleeve 21 from a toner supply member 23a holding a toner thin layer between adjacent same-polarity polarization sections S1, S2 polarized to the same polarity at the required interval on the magnet member 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer,
In particular, the present invention relates to a developing device in which a magnet member having a plurality of magnetic poles is provided on the inner peripheral side of a developing sleeve, and the toner in the developer on the developing sleeve is supplied to an image carrier to perform development. .

[0002]

2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines and printers, various developing devices have been used to supply toner to an image carrier to perform development. Is known as a one-component developing type developing device using only toner as a developer, and a two-component developing type developing device using a developer containing toner and carrier.

Here, in the two-component developing system using the developer containing the toner and the carrier as described above, generally, as shown in FIG. The first and second stirring and conveying members 13 and 14 are provided in the conveying units 11 and 12, respectively, and the stirring and conveying members 13 and 14 are rotated to mix and stir the developer 1 while the first and second stirring and conveying members 13 and 14 are rotated. A magnet member 15 having a plurality of magnetic poles is provided on the inner peripheral side of the developer 1 that has been conveyed by the second conveying units 11 and 12 and that has been conveyed while being mixed and stirred in the second conveying unit 12. And was supplied to the developing sleeve 16. Then, the developing sleeve 16 thus supplied with the developer 1 is rotated, and the developer 1 supplied to the developing sleeve 16 is constrained by the magnetic force of the magnet member 15 while the image carrier 2 is held.
While being conveyed to the side, the amount of the developer 1 thus conveyed is regulated by the regulating member 17 provided with the developing sleeve 16 with a required gap, and then the developer 1 is guided to the image carrier 2. The toner in the developer 1 is supplied to the image carrier 2 to perform the development.

However, in the developing device as described above, in addition to the developing sleeve 16, the first and second developing devices are provided as described above.
In order to carry out the mixing and stirring of the developer 1 by rotating the respective stirring and carrying members 13 and 14, the rotating device with a large driving torque must be used to carry out these rotations, and the device becomes large. And the cost is high,
Further, there is a problem that the vibrations during these rotations increase, and image noise is generated in an image formed by the vibrations.

Therefore, in the prior art, in order to reduce the driving torque when rotating the developing sleeve 16 or the like as described above to reduce the size of the apparatus and to suppress the generation of image noise due to vibration during rotation, JP 61
As described in Japanese Patent Publication No. -80280, mixing and stirring of the developer by the first and second stirring and conveying members is not performed, and as shown in FIG. Development sleeve 1 holding developer 1
6 was just developed to supply toner.

In the developing device for replenishing the developing sleeve 16 with the toner from the toner replenishing member 18, the developer 1 on the developing sleeve 16 with the replenished toner is restrained by the magnetic force of the magnet member 15. The developer 1 is conveyed to the image carrier 2 side as the developing sleeve 16 rotates, and the developer 1 is agitated during the conveyance, and the developing sleeve 16
The amount of the developer 1 on the upper side is regulated by the regulating member 17 provided with the developing sleeve 16 with a required space,
After that, the developer 1 is guided to the image carrier 2 by the developing sleeve 16, and the toner in the developer 1 is supplied to the image carrier 2 so as to perform the development.

Here, in any of the developing devices shown in FIGS. 1 and 2, the magnet member 15 on the inner peripheral side of the developing sleeve 16 is generally magnetized in order of N pole and S pole. This magnet member 15 is used.
By the magnetic force of the developer 1 on the developing sleeve 16.
The developer 1 is conveyed to the image carrier 2 side with the rotation of the developing sleeve 16 while restraining.

However, as described above, the developer 1 on the developing sleeve 16 is restrained by the magnetic force of the magnet member 15 in which the N pole and the S pole are sequentially magnetized, and the developing sleeve 16 rotates as it rotates. When the developer 1 is conveyed, as shown in FIG. 3, the magnetic chain composed of the carrier 1b and the toner 1a formed of the developer 1 on the developing sleeve 16 always causes the magnetic line of force of the magnet member 15 to be generated. The magnetic chain is strongly restrained by the magnetic force along the developing sleeve 16 in this state.
The developer 1 on the developing sleeve 16 collides with the regulating member 17 and is regulated as it rolls.

When the magnetic chain of the developer 1 collides with the regulating member 17 while being strongly restrained by the magnet member 15 as described above, the collision causes the carrier 1b in the developer 1 to be spent, and the developing sleeve. There is a problem that the developer 1 on 16 deteriorates gradually, and when the developer 1 is used for development, various adverse effects such as background fog and uneven density occur on an image to be formed, and a developing sleeve. The resistance against rotation of 16 also becomes large, and thus a rotating device having a large driving torque must be used to rotate the developing sleeve 16, which causes a problem that the device becomes large and the cost is high.

Particularly, in the case where only the toner is supplied from the toner replenishing member 18 to the developing sleeve 16 holding the developer 1 as in the developing device shown in FIG.
Since the replacement of the carrier 1b on the developing sleeve 16 is small, when the carrier 1b in the developer 1 is spent as described above, various adverse effects occur on an image formed immediately, and the toner replenishing member 18 develops the image. The toner 1a is replenished to the tip of the magnetic chain composed of the developer 1 at a position where the toner 16a is replenished to the sleeve 16, and the replenished toner 1a is not sufficiently mixed and stirred with the carrier 1b. The toner 1a which is guided to the second stage 2 and used for the development or the replenished toner 1a
There is a problem that the characteristic of the developing sleeve 16 is deteriorated by being attached to the surface of No. 6 and thus various adverse effects such as background fog and uneven density occur on the formed image.

[0011]

SUMMARY OF THE INVENTION The present invention is a developing device used in an image forming apparatus such as a copying machine or a printer, in which a magnetized magnet member is provided on the inner peripheral side of a developing sleeve, It is an object of the present invention to solve the above-mentioned various problems in a developing device that supplies toner in a developer on a sleeve to an image carrier to perform development.

That is, according to the present invention, in the above-described developing device, the developing sleeve can be smoothly rotated with a small torque, the device can be downsized, the cost can be reduced, and the developing sleeve can be rotated. There is little vibration at the time, and the occurrence of image noise due to vibration is suppressed. Further, when the amount of the developer on the developing sleeve is regulated, the carrier in the developer is spent and the developer is deteriorated. However, it is an object of the present invention to stably perform good image formation over a long period of time.

[0013]

According to the present invention, in order to solve the above-mentioned problems, a magnet member having a plurality of magnetic poles is provided on the inner peripheral side of the developing sleeve, and a developer member on the developing sleeve is provided. In the developing device adapted to supply the toner to the image carrier to perform the development, the developing sleeve of the developing sleeve between the same-polarized portions magnetized to the same pole adjacent to each other in the magnet member at a required interval. To the outer peripheral side, a developer agitating section for agitating the developer, a regulating section for regulating the amount of the developer on the developing sleeve, and a toner replenishing member holding a thin toner layer, replenishing the developer on the developing sleeve with toner. And a toner replenishing section for controlling the operation.

Here, as described above, the developer stirring portion, the regulating portion, and the toner are provided on the outer peripheral side of the developing sleeve between the homopolar magnetized portions which are magnetized to the same pole adjacent to each other through the required distance in the magnet member. In providing the replenishment section, the order of providing these is not particularly limited. For example, on the outer peripheral side of the developing sleeve in the range between the same-polarized sections, from the upstream side to the downstream side of the developer conveying direction by the developing sleeve. The developer agitating section, the regulating section and the toner replenishing section may be provided in this order, or the toner replenishing section, the developer agitating section and the regulating section may be provided in this order.

[0015]

In the developing device according to the present invention, as described above, in the magnet member provided on the inner peripheral side of the developing sleeve, between the same-polarized portions magnetized to the same pole adjacent to each other with a required gap. On the outer peripheral side of the developing sleeve, a developer agitating portion for agitating the developer, a regulating portion for regulating the amount of the developer on the developing sleeve, and a toner replenishing member holding a thin toner layer are used for the developer on the developing sleeve. Since the toner replenishing section for replenishing the toner is provided, the toner and the carrier in the developer are agitated in the portion where the magnetic binding force between the same-polarized portions is weak, and the amount of the developer on the developing sleeve is reduced. The toner is supplied to the developing sleeve which is regulated and holds the developer.

Therefore, in the developing device according to the present invention, like the conventional developing device, the developing sleeve is rotated while the developer on the developing sleeve is strongly restrained by the magnetic force along the magnetic line of force of the magnet member. Therefore, it does not move while rolling and collide with the regulating member, so that the spent of the carrier due to the collision with the regulating member is suppressed and the deterioration of the developer is reduced, and the developer is held by the developing sleeve in this way. When the developer is replenished with toner from the toner replenishing member, the toner is replenished to the tip of the magnetic chain of the developer, and the replenished toner is guided to the image carrier without being sufficiently mixed and stirred with the carrier. It is also possible that the toner used for development or replenished toner adheres to the surface of the developing sleeve and deteriorates the characteristics of the developing sleeve. No.

Here, as described above, between the homopolar magnetized portions of the magnet member provided on the inner peripheral side of the developing sleeve, the developer stirring section, the regulating section and the toner replenishing section are provided on the outer peripheral side of the developing sleeve. In providing the toner, for example, as shown in FIG. 4, on the outer peripheral side of the developing sleeve 21 between the homopolarized portions N of the magnet member 22, the toner is replenished from the upstream side to the downstream side in the conveying direction of the developer 1. If the portion 23, the developer agitating portion 24, and the regulating portion 25 are provided in this order, first, the toner 1a is replenished from the toner replenishing portion 23 to the developer 1 having a weak magnetic binding force on the developing sleeve 21, and then the toner 1a is replenished. The developer 1 thus replenished with the toner 1a is sufficiently agitated in the developer agitating section 24 in a state where the magnetic restraining force is weak, and then the developer 3 replenished and agitated with the toner 1a as described above. Developer 1 on 21 is guided to the regulating unit 25 with a weak state of magnetic binding force, the regulating portion 25
At, the amount of the developer 1 on the developing sleeve 21 is regulated. Therefore, when the toner 1a is replenished from the toner replenishing section 23 to the developer 1 on the developing sleeve 21, the toner 1a is less likely to be replenished and adhered directly to the surface of the developing sleeve 21, and the developer 1 is also reduced. Is not strongly bound to the surface of the developing sleeve 21 and collides with the regulating member or the like.
The developer 1 on No. 1 is not deteriorated by the regulation by the regulation unit 25.

Further, as shown in FIG. 5, on the outer peripheral side of the developing sleeve 21 between the homopolarized portions N, N of the magnet member 22, the developer is transferred from the upstream side to the downstream side in the conveying direction of the developer 1. When the stirring section 24, the regulating section 25, and the toner replenishing section 23 are provided in this order, first, the developer 1 on the developing sleeve 21 is sufficiently stirred in the developer stirring section 24 in a state where the magnetic binding force is weak. The developer 1 on the developing sleeve 21 thus stirred is guided to the regulating portion 25 in a state where the magnetic binding force is weak, and the regulating portion 25 regulates the amount of the developer 1 on the developing sleeve 21. The toner 1a is replenished from the toner replenishing portion 23 to the developer 1 on the developing sleeve 21 regulated as described above. Here, in order to replenish the toner 1a to the developer 1 on the developing sleeve 21 after the toner is sufficiently stirred and regulated in such a state where the magnetic binding force is weak, the toner on the developing sleeve 21 immediately before the toner 1a is replenished. The toner concentration of the developer 1 is corrected to be substantially uniform, and the replenished toner 1a is easily charged to a predetermined charge amount by the time it is transported to the development area, and is used for development. It becomes possible to always keep the charge amount of the toner 1a in the developer 1 appropriate.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings.

(Embodiment 1) In the developing device of this embodiment, as shown in FIG. 6, the opening portion of the main body 20 of the developing device is made to face the drum-shaped image carrier 2. A cylindrical developing sleeve 21 is rotatably provided, and a magnet member 22 having a plurality of magnetic poles is provided on the inner peripheral side of the developing sleeve 21.

Here, S is added to the magnet member 22.
In providing the magnetic poles of the poles and the N poles, in this embodiment, they are adjacent to the portion of the magnet member 22 on the inner side of the apparatus main body 20 on the side opposite to the developing section facing the image carrier 2 with a required space. In this way, the same pole magnetized portions S1 and S2 magnetized to the same S pole are provided.

Then, from the homopolarized portions S ₁ and S ₂ magnetized to the same S pole in this way, to the downstream side in the conveying direction of the developer 1, N ₂ , S ₃ , S ₄ , and N ₁ are arranged in this order. A magnetic pole is provided on the magnetic pole S, and the magnetic pole S is magnetized in the vicinity of the developing unit facing the image carrier 2.
₃ and S ₄ are positioned. In this embodiment, the magnet member 22 is provided with the homopolar magnetized portions S ₁ and S ₂ magnetized to the S pole. However, the polarities of the magnetic poles in the homopolar magnetized portion are the S pole and the N pole. It is also possible to use any of the above, and as shown in FIGS. 4 and 5, it is possible to make the homopolar magnetized portion to be the N pole, and from the homopolar magnetized portions S ₁ and S _2. The order of the magnetic poles magnetized toward the downstream side of the developer 1 in the transport direction is not limited to the above order.

Further, in this embodiment, the outer circumference of the developing sleeve 21 between the homopolarized portions S ₁ and S ₂ provided on the magnet member 22 as described above inside the apparatus main body 20. Side, a developer stirring portion 24 for stirring the developer 1 from the upstream side to the downstream side in the transport direction of the developer 1, a regulating portion 25 for regulating the amount of the developer 1 on the developing sleeve 21, and a developing device. Toner replenishing member 23 holding a thin toner layer on developer 1 on sleeve 21
A toner replenishing section 23 for replenishing the toner 1a from a is provided.

Here, the developer stirring section 24 is provided with a stirring roller 24a for stirring the developer 1, and the regulating section 25 regulates the amount of the developer 1 on the developing sleeve 21. The regulating member 25a is provided so as to face the developing sleeve 21 with a required gap.

Further, as described above, the toner replenishing section 2 for replenishing the toner 1a to the developer 1 on the developing sleeve 21.
3 is a toner replenishing member 2 for holding a thin toner layer.
As the reference numeral 3a, as shown in FIG. 7, a toner replenishing roller 23a having a cylindrical shape and a plurality of N poles and S poles sequentially magnetized along the circumferential direction is used.
Is rotatably provided close to the peripheral surface of the developing sleeve 21, a toner regulating plate 23b is provided for the toner replenishing roller 23a, and the toner regulating plate 23b is attracted by the magnetic force of the toner replenishing roller 23a. The toner supply roller 23a is brought into contact with the peripheral surface thereof.

Further, in this embodiment, a toner storage portion 26 for storing the toner 1a is provided in the toner storage portion 26 at a position opposite to the developing sleeve 21 via the toner supply roller 23a. Rotating feeding member 2
6a is provided, and the feeding member 26a is rotated to supply the toner 1a in the toner containing portion 26 to the toner replenishing roller 23a.

Then, while the toner replenishing roller 23a supplied with the toner 1a is rotated to guide the toner 1a to the developing sleeve 21, it is attracted by the magnetic force of the toner replenishing roller 23a as described above. , The toner replenishing roller 23a is brought into contact with the toner replenishing roller 23a by the toner regulating plate 23b in contact with the peripheral surface of the toner replenishing roller 23a.
The amount of the toner 1a in a is regulated, the toner 1a is charged at the contact portion with the toner regulation plate 23b, and the toner 1a thus charged in the thin layer state on the surface of the toner replenishing roller 23a is The developer 1 in the developing sleeve 21 is replenished from the toner replenishing roller 23a. Here, the toner 1a is supplied from the toner supply roller 23a in this way to the developing sleeve 2
Although not shown in the drawings, a bias voltage is applied between the developing sleeve 21 and the toner replenishing roller 23a to replenish the toner to the first replenishing roller 1.
The amount of toner 1a replenished from a to the developing sleeve 21 is adjusted.

In this embodiment, the toner replenishing member 23a for replenishing the developing sleeve 21 with the toner 1a.
As described above, a cylindrical toner replenishing roller 23a having a large number of N poles and S poles sequentially magnetized along the circumferential direction as described above.
However, it is also possible to use a material made of a conductive material such as aluminum, rubber or resin which has been conventionally used.

When developing with the developing device of this embodiment, the developing sleeve 21 is rotated in the direction opposite to the image carrier 2 and the developer 1 held on the developing sleeve 21 is carried on the image. The developer held on the developing sleeve 21 by the action of the magnetic poles S ₃ and S ₄ of the magnet member 22 which is guided to the developing unit facing the body 2 and is magnetized to have the same polarity in the vicinity of the developing unit as described above. The restraining force of No. 1 was weakened, and the toner 1a in the developer 1 was supplied to the image carrier 2 in the powder cloud state to perform the development. When the toner 1a in the developer 1 is supplied from the developing sleeve 21 to the image carrier 2 as described above,
When the carrier 1b in the developer 1 is erroneously supplied to the image carrier 2, the carrier recovery magnet body provided in the apparatus main body 20 at a position downstream of the developing unit in the rotational direction of the image carrier 2. The carrier 1b supplied to the image carrier 2 by means of 27 is collected.

After the toner 1a in the developer 1 is supplied to the image carrier 2 for development as described above, the developer 1 in which the toner 1a is consumed as the developing sleeve 21 rotates Was returned to the inside of the apparatus main body 20.

Then, the developer 1 from which the toner 1a has been consumed in this way is returned to the inside of the apparatus main body 20, and the developer 1 is rotated by the developing sleeve 21 so that the same-polarized portion S ₁ of the magnet member 22 is magnetized. , when guided to the portion of S _2, first, in the developer agitating portion 24 located on the upstream side in the transport direction of the developer 1 between the same poles magnetized portion S _1, S _2, as described above The developer 1 in which the toner 1a has been consumed is agitated by the agitating roller 24a in a state where the magnetic binding force is weak.

After stirring the developer 1 in this way, the developer 1 on the developing sleeve 21 is provided on the regulating portion 25 with a weak magnetic binding force as the developing sleeve 21 rotates. The regulating member 25a regulates the amount of the developer 1 on the developing sleeve 21. Here, when the amount of the developer 1 on the developing sleeve 21 is regulated by the regulating member 25a in the state where the magnetic force is weak, the developer 1 is not subjected to a large stress and deteriorated. The developer 1 can now be used stably over a long period of time. Further, the driving torque of the developing sleeve 21 can be reduced, and vibration and noise in the developing device are reduced.

After the amount of the developer 1 on the developing sleeve 21 is regulated as described above, the developing sleeve 2
The toner replenishment section 2 supplies the developer 1 regulated by the rotation of the toner 1.
3, the developer 1 regulated by the developing sleeve 21 is charged with a predetermined amount of toner 1a charged from a toner replenishing roller 23a provided in the toner replenishing section 23.
Of the developer 1 thus replenished with the toner 1a
Lead to the image carrier 2 as the developing sleeve 21 rotates,
It was used again for development.

Here, if the toner 1a is replenished from the toner replenishing roller 23a after the developer 1 after development is agitated as described above, a large amount of toner 1a is consumed during development, and the developing sleeve 21 is consumed. Even if the toner concentration in the developer 1 above greatly varies in the axial direction of the developing sleeve 21, the toner concentration in the developer 1 on the developing sleeve 21 becomes substantially uniform in the axial direction of the developing sleeve 21 by the above stirring. In such a state, the toner 1a replenished to the developer 1 on the developing sleeve 21 is easily and sufficiently charged to a predetermined charge amount before being transported to the developing section. became. Therefore, when the toner 1a is supplied from the developing sleeve 21 to the image carrier 2 to perform the development, the toner 1a is
No more scattering from inside the developing device, and no more background fogging or uneven density in the formed image.

In the developing device of this embodiment, the magnet member 22 on the inner peripheral side of the developing sleeve 21 is magnetized to the same S pole so as to be adjacent to each other with a required gap therebetween. In addition to S ₁ and S ₂ , N
A magnet member having a large number of magnetic poles of ₁ , N ₂ , N ₃ , S ₃ , and N ₄ is used.
The number 2 is not limited to the above-described one. For example, as shown in FIG. 8, in addition to the homopolarized portions S ₁ and S ₂ , the developing sleeve 21 is provided in the developing portion facing the image carrier 2. You may make it use the magnet member 22 which provided only one N pole in the part, If such a magnet member 22 is used,
By reducing the diameters of the magnet member 22 and the developing sleeve 21, the entire developing device can be downsized.

(Embodiment 2) In the developing device in this embodiment, as shown in FIG. 9, the developing sleeve 21 is provided on the outer peripheral side between the homopolarized portions S ₁ and S ₂ provided on the magnet member 22. , Developer agitating section 24, and regulating section 25
In order to provide the toner replenishing section 23 and the toner replenishing section 23, the order in which they are provided is changed so that the developer 1 is conveyed between the homopolarized sections S ₁ and S ₂ of the magnet member 22. From the upstream side to the downstream side in the direction, the toner replenishing section 23, the developer stirring section 24, and the regulating section 25 are provided in this order on the outer peripheral side of the developing sleeve 21.

Here, also in the developing device of this embodiment, the toner 1a in the developer 1 held on the developing sleeve 21 is transferred from the developing sleeve 21 to the image carrier 2 as in the developing device of the first embodiment. To the developing sleeve 21. After developing in this manner, the developing sleeve 21
The developer 1 in which the toner 1a has been consumed as described above is returned to the inside of the apparatus main body 20 in accordance with the rotation of.

The developer 1 from which the toner 1a has been consumed in this way is returned to the inside of the apparatus main body 20, and this developer 1 is rotated by the developing sleeve 21 so that the same-polarized portion S ₁ of the magnet member 22 is magnetized. , S ₂ in the developing device of this embodiment, first, in the toner replenishing section 23 located upstream in the carrying direction of the developer _{1 in} the homopolarized sections S ₁ , S ₂ , The toner 1a is replenished from the toner replenishing roller 23a to the developer 1 in which the toner 1a is consumed in the state where the magnetic force is weak.

Next, after replenishing the toner 1a to the developer 1 in this way, the developer 1 is guided to the developer agitating section 24 in a state where the magnetic binding force is weak, and in the developer agitating section 24, the toner is agitated. The developer 1 replenished with 1a was agitated in a state where the magnetic binding force was weak. In this way toner 1a
When the replenished developer 1 is conveyed and stirred in a state where the magnetic binding force is weak, the replenished toner 1a is not pressed and adhered to the surface of the developing sleeve 21, and the toner 1a is replenished. The developer 1 was sufficiently stirred, and the amount of the toner 1a in the developer 1 became constant.

After the developer 1 is stirred in this way, the developer 1 is further rotated with the rotation of the developing sleeve 21, and the developer 1 is provided with a regulating member 25a provided on the regulating portion 25 in a state where the magnetic force is weak. The amount of the developer 1 on the developing sleeve 21 is regulated by the regulating member 25a, and the developer 1 regulated in this way is guided to the image carrier 2 as the developing sleeve 21 rotates to be developed again. I decided to use it. When the developer 1 on the developing sleeve 21 is regulated by the regulating member 25a in such a state that the magnetic force is weak, the developer 1 is not subjected to a large stress and deteriorates. The developer 1 can now be stably used.

[0041]

As described above in detail, in the developing device of the present invention, the toner in the developer is supplied to the image carrier from the developing sleeve provided with the magnet member having a plurality of magnetic poles on the inner peripheral side. In developing by developing, since the first and second stirring / conveying members for conveying the developer while mixing and stirring the developer are not provided separately from the developing sleeve,
In order to rotate these agitating / conveying members, it is not necessary to use a rotating device having a large drive torque, the device can be downsized and the cost can be reduced, and vibration during rotation can be reduced. The occurrence of the phenomenon is also suppressed, and stable image formation can be performed.

Further, in the developing device according to the present invention, between the magnetized portions having the same poles magnetized so as to be adjacent to each other in the magnet member so as to be adjacent to each other with a required gap, on the outer peripheral side of the developing sleeve. A developer stirring portion for stirring the developer, a regulating portion for regulating the amount of the developer on the developing sleeve, and a toner replenishing portion for replenishing the developer on the developing sleeve with toner from the toner replenishing member holding the thin toner layer. Are provided to stir the toner and the carrier in the developer in the portion where the magnetic binding force between the magnetized portions is weak, and the amount of the developer on the developing sleeve is regulated so that the developer is retained. Since the developing sleeve is replenished with toner, the developer on the developing sleeve is strongly restrained by the magnetic force of the magnet member. Since it does not collide with the control member, the deterioration of the developer due to the spent of the carrier is suppressed, and even compared with the conventional developing device in which the developer on the developing sleeve is replenished with toner. Good image formation can be stably performed over a long period of time.

Further, in the developing device according to the present invention, the toner and the carrier in the developer are agitated or the developer on the developing sleeve is replenished with the toner in the portion where the magnetic binding force is weak as described above. Therefore, the replenished toner is guided to the image carrier and used for development without being sufficiently mixed and stirred with the carrier, or the replenished toner adheres to the surface of the developing sleeve to deteriorate the characteristics of the developing sleeve. As a result, good image formation without background fog or density unevenness can be stably performed.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a conventional developing device provided with first and second stirring and conveying members for conveying a developer while mixing and stirring the developer.

FIG. 2 is a schematic explanatory view of a conventional developing device in which toner is replenished from a toner replenishing member to a developing sleeve holding a developer.

FIG. 3 is a partially enlarged explanatory view showing a state in which a developer is conveyed as the developing sleeve rotates in a conventional developing device.

In the developing device according to the present invention, the developer on the developing sleeve has a toner replenishing portion, a developer stirring portion, and a regulating portion between the homopolar magnetized portions provided on the magnet member as the developing sleeve rotates. It is a partial enlarged explanatory view showing a state of moving in the order of.

FIG. 5 is a view showing a developing device according to the present invention, in which the developer on the developing sleeve is magnetized between magnetized parts provided on a magnet member, and the developer agitating portion, the regulating portion, and the toner replenishing portion as the developing sleeve rotates. It is a partial enlarged explanatory view showing a state of moving in the order of.

FIG. 6 is a schematic explanatory view of the developing device according to the first embodiment of the present invention.

FIG. 7 is a schematic view of a toner replenishing roller used in an embodiment of the present invention.

FIG. 8 is a schematic explanatory view showing an example of a developing device using a magnet member having a small number of magnetic poles in the developing device of the first embodiment.

FIG. 9 is a schematic explanatory diagram of a developing device according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 developer 1a toner 2 image carrier 21 developing sleeve 22 magnet member 23 toner replenishing section 23a toner replenishing member (toner replenishing roller) 24 developer stirring section 25 regulating section S ₁ , S ₂ homopolar magnetized section

Claims (1)

[Claims] 1. A developing device in which a magnet member having a plurality of magnetic poles is provided on the inner peripheral side of a developing sleeve, and the toner in the developer on the developing sleeve is supplied to an image carrier to perform development. In the magnet member, a developer stirring portion for stirring the developer is provided on the outer peripheral side of the developing sleeve between the homopolar magnetized portions that are magnetized to be adjacent to each other with a required gap therebetween. A developing device comprising: a regulating portion for regulating the amount of the developer; and a toner replenishing portion for replenishing the developer on the developing sleeve with toner from a toner replenishing member holding a thin toner layer.