JP3356948B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine, a printer, and a facsimile machine, and more particularly to an electrophotographic apparatus for forming a toner layer on a developing roll using a two-component developer composed of a toner and a carrier. In the developing device.

[0002]

2. Description of the Related Art Conventional developing devices include a two-component developing device using a two-component developer containing a toner and a carrier and a one-component developing device using a one-component developer consisting of a single toner.
The component developing device is advantageous in that it does not use a carrier and does not require a mechanism for controlling the mixture ratio of the developer, which is advantageous for miniaturization and cost reduction, and has the advantage that the carrier does not adhere to the photoreceptor. It is used in a color electrophotographic apparatus in which containers are arranged.

In particular, a non-magnetic one-component developing device is disclosed in Japanese Patent Publication No. 7-43546, Japanese Utility Model Publication No. 7-20683, and the like. As for the magnetic one-component developing device,
-48901.

Further, in a non-magnetic one-component developing apparatus which does not use a magnetic toner, an example in which a magnet roll is used as a transport roll is disclosed in JP-A-55-77764.
As described in JP-A-3-59576 and JP-A-61-239266, a method in which contact development is performed using a sponge roll as a developing roll is provided between the toner layer on the developing roll and the photoreceptor. A method of performing non-contact development by providing a gap has been proposed.

[0005]

By the way, when a conventional non-magnetic one-component developing apparatus is used to obtain a high-speed and high-definition color image or to apply low-temperature fixing required for power saving. There is a tendency for toner filming to occur on the developing roll due to mechanical stress applied to the toner on the developing roll by a blade in contact with the developing roll, thereby deteriorating image quality and shortening the replacement life of the developing device. there were.

In the method of performing contact development using a sponge roll as a developing roll, when used at a high speed, the shape of the developing sponge roll tends to be deformed, and the replacement cycle tends to be short.

Further, in the method of performing non-contact development by providing a gap between the toner layer on the developing roll and the photoreceptor, the reproducibility of fine halftone images and gradation tends to be insufficient. .

A first object of the present invention is to provide a developing apparatus configured to perform the development by forming a toner layer on a developing roll by eliminating the above-mentioned drawbacks, in which a so-called toner film is formed on the developing roll. An object of the present invention is to provide a developing device capable of preventing filming from occurring and ensuring high speed and high image quality.

A second object of the present invention is to provide a non-magnetic one-component developing apparatus which can be applied to an electrophotographic apparatus which performs low-temperature fixing required for power saving.

[0010]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In addition, the developing device of the present invention has a structure in which a toner layer is formed on the surface.
The image roll is brought into contact with the photoreceptor,
The developing roll has an elastic roll fitted on a metal sleeve.
And the first and the second rollers are arranged in close proximity to the developing roll.
A second magnet roll is provided rotatably, and
The first magnet roll is connected to the second magnet roll.
With respect to the developing roller in the rotation direction upstream of the developing roll,
A distributing section at an intermediate portion between the first and second magnet rolls;
Material is provided, and the cap held by the first magnet roll is provided.
The developer containing the rear and the toner is supplied to the second magnet row.
And the first and second magnets
The developer held on the roll is brought into contact with the developing roll.
Between the first magnet roll and the developing roll.
Between the first magnet and the toner on the developing roll
An electric field in the direction of suction is applied to the roll, and the second
The second mark between the gnet roll and the developing roll.
Move the toner on the gnet roll to the developing roll
The electric field in the direction of
Is formed.

In order to achieve the above object, the present invention
The developing device senses the developing roll with the toner layer formed on the surface.
In a developing device for performing development by contacting with an optical body,
The image roll is configured by fitting an elastic roll to a metal sleeve
The first and second magnets are located in close proximity to the developing roll.
A troll is rotatably provided, and the first magnet
Roll with respect to the second magnet roll.
It is arranged on the upstream side in the rotation direction of the developing roll,
A distributing member is provided at an intermediate portion of the second magnet roll,
Remove the carrier and toner held by the first magnet roll
Dispensing the developer to the second magnet roll.
And the developing device held by the first magnet roll
The developer is brought into contact with the developing roll in the counter direction, and the
The developer held by the magnet roll 2
In the same direction as the first and second magnets.
Between the trolley and the developing roll.
Move the toner on the magnet roll to the developing roll.
The electric field in the direction of
In this case, a layer is formed.

Further, in order to achieve the above object, the present invention
The developing device senses the developing roll with the toner layer formed on the surface.
In a developing device for performing development by contacting with an optical body,
The image roll is composed of an elastic roll,
A first magnet roller is provided on the lower side in close proximity to the developing roller.
The first magnet is arranged rotatably and the first magnet
The second side in close proximity to the developing roll above the trawl;
Of the first magnet is rotatably arranged.
The developer absorbed and pumped by the gunnet roll is transferred to the second
The first magnet is distributed to a magnet roll.
The developing roll between the net roll and the developing roll
A method of sucking the upper toner onto the first magnet roll
Direction electric field to act on the second magnet roll and the front
Between the developing roll and the second magnet roll.
An electric field is applied to move the toner to the developing roll.
To form a toner layer on the developing roll.
It is a thing.

In order to achieve the above object, the present invention
The developing device senses the developing roll with the toner layer formed on the surface.
In a developing device for performing development by contacting with an optical body,
The image roll has a metal sleeve fitted with an elastic roll
And close to the developing roll below the developing roll.
And the first magnet roll is rotatably arranged
The developing roller is located above the first magnet roll.
The second magnet roll can be rotated in close proximity to the
At the periphery of the first magnet roll.
The amount of developer that is absorbed and pumped up by one magnet roll
The regulating portion for regulating provided, and the gap G ₀ of the regulating portion, said
Formed by a first magnet roll and the developing roll
First and gap G _1, wherein said second magnet roll that
The second gap G ₂ formed by the developing roll corresponds to the following (1)
And the relationship of the expression (2) is satisfied,
The developer drawn by the second magnet roll
The first magnet roll and the front
Between the developing roll and the toner on the developing roll.
An electric field in the direction of suction is applied to the first magnet roll.
Between the second magnet roll and the developing roll.
Developing the toner on the second magnet roll
An electric field is applied to the roll to move the roll.
A toner layer is formed on the roller. G ₁ <G ₀ (1) G ₂ ≦ G ₀ −G ₁ (2) By adopting the above configuration, the toner film is formed on the developing roll.
Lumming does not occur.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.
An example will be described. (1) First Embodiment A developing device 8 according to the present embodiment shown in FIG. 1 includes a developing roll 2 facing a photoreceptor 1 and a first magnet roll 3 on the upstream side in the rotation direction of the developing roll 2. A second magnet roll 4 on the downstream side, a distribution member 5, a stirring blade 7 provided in a toner hopper 6, a DC bias power supply 14,1.
5, 16, an AC bias power supply 17, a scraper 10, a stirring member 9, and the like. The toner in the toner hopper 6 is supplied to the vicinity of the stirring member 9 from the opening 13 by the stirring blade 7, and is stirred with the developer 11 by the stirring member 9. The mixture is mixed and guided to the first magnet roll 3. The developer conveyed by the first magnet roll 3 is divided into two by the distribution member 5 and is also supplied to the second magnet roll 4 side.

The first magnet roll 3 rotates counterclockwise in FIG. 1 so as to bring the developer magnetic brush 53 into rotational contact with the development roll 2 in the counter direction, and furthermore, a bias voltage is applied to the first magnet roll 3. Is applied to apply an electric field (reverse electric field) for sucking the toner on the developing roll 2 to scrape off the toner remaining on the developing roll (after developing the electrostatic latent image on the photoconductor 1). The magnet roll 3 is to be attracted.

[0016] Also, the second magnet roll 4, as contacting rotating the developer magnetic brush 54 to the developing roller 2 in the same direction, rotating it clockwise Te 1 smell, furthermore, the second magnet roll 4 To form a toner layer 12 on the developing roll 2.

The toner layer 12 has a toner charge amount of 5 to 30 μm.
c / g, preferably 10 to 25 μc / g, and the toner adhesion amount is 0.4 to 1.5 mg / cm ² , preferably 0.6 to 1.2 mg / cm.
Formed to be ² .

Thereafter, the rotation of the developing roll 2 (counterclockwise in FIG. 1) causes the toner layer 12 on the developing roll 2 to be conveyed to a portion facing the photoreceptor 1, and the electrostatic latent image on the photoreceptor 1 to be transferred. And a developing electric field is applied to the developing section to form a toner image.

As described above, the first magnet roll 3
The developer composed of the toner and the carrier that has been transported upward by the distribution member 5 and adsorbed by the second magnet roll 4 is transported by the second magnet roll 4 and contacts the development roll 2 by the developer magnetic brush 54. As described above, the developer is composed of the toner and the carrier, and the toner and the carrier are charged to have opposite polarities by frictional charging during conveyance and stirring.
In this state, the second magnet roll 4 and the developing roll 2
By applying an electric field (forward electric field) in a predetermined direction during the period, only the toner is separated from the developer held by the second magnet roll 4 and moves onto the developing roll 2,
A substantially uniform toner layer can be formed. Thereafter, the toner layer on the developing roll 2 comes into contact with the electrostatic latent image portion on the photoreceptor 1, and the toner is transferred to perform development. That is, in the present invention, there is no need to provide a blade that comes into contact with the developing roll 2, and it is possible to form a substantially uniform layer of toner on the developing roll 2 by charging the toner. No filming due to the toner occurs on the upper side.

Further, in the present invention, as described later, the first
Alternatively, since a control unit for controlling the number of rotations of the second magnet rolls 3 and 4 and the bias voltage is provided, the number of rotations of the first or second magnet rolls 3 and 4 may be changed, or the bias voltage of the second magnet roll 4 may be changed. To adjust the second electric field strength acting between the second magnet roll 4 and the developing roll 2 or the bias voltage of the first magnet roll 3 to adjust the first magnet roll 3 and the developing roll. 2
Can be selected, and the amount of toner adhering to the developing roll 2 can be adjusted, so that the stability can be improved and the color image quality can be kept constant for a long time.

The rotation direction of the developing roller 2 and the photosensitive member 1 may be the same or the counter direction, but the peripheral speed ratio k is 2 or less. Preferably, in the same direction, 1 ≦
k ≦ 1.5, and the speed difference ΔV is 0 ≦ ΔV ≦ 50.
mm is more desirable. In particular, in such a configuration, the bias voltage is set to 1 to 10 KHz, 100 to 1000 V.
By superimposing the AC voltage, it is possible to achieve both image uniformity and prevention of photoreceptor wear.

The developing roll 2 has a low hardness (for example, a rubber hardness of about 15 to 35 degrees (J) on a metal sleeve (for example, Ni electroformed sleeve or SUS sleeve) of about 20 to 60 μm.
The rubber roll of IS-A)) is fitted to form the developing roll 2 having elasticity. A metal sleeve such as a Ni electroformed sleeve prevents the developing roll 2 from being scratched or worn, and reduces the thickness so that the elasticity of the rubber roll can be maintained. It is intended to be obtained. Therefore, when the printing speed is high, or when the peripheral speed ratio k between the developing roll 2 and the photoconductor 1 is slightly large (k =
(1.5 to 2.0), there is an effect that the replacement cycle of the developing roll 2 and the photoconductor 1 can be lengthened. The developing roll is
Those having a diameter of 15 to 40 mm were used.

The rubber roll may be either an insulating roll or a conductive roll. In the case of an insulating roll (for example, a resistance value of about 10 ¹³ to 10 ¹⁶ Ωcm), the power for applying the developing bias is supplied by the developing roll. While from the roll surface,
In the case of a conductive roll (for example, a resistance value of about 10 ⁷ to 10 ⁸ Ωcm or less), there is an advantage that power can be supplied using the axis of the developing roll.

When the printing speed is relatively low, or when the peripheral speed between the developing roll 2 and the photosensitive member 1 is almost equal, the developing roll 2 is not provided with a metal sleeve and has a low hardness (for example,
A rubber roll having a rubber hardness of about 15 to 55 degrees (JIS-A) (or a surface-coated rubber roll) may be used.

The first magnet roll 3 forms a gap (first gap; abbreviated as G ₁ ) with the developing roll 2 and distributes the developer held by the first magnet roll 3 to the distribution member 5. And a gap (first distribution gap). The first magnet roll 3 conveys the developer 11 to the vicinity of the distributing member 5, makes the developer introduced from the gap with the distributing member 5 come into rotational contact with the developing roll 2 in a counter direction, and contacts the first magnet roll 3. By applying a reverse electric field between the developing rolls 2, the toner layer on the developing rolls 2 is sucked and removed.
More preferably, the above-mentioned reverse electric field is formed by superimposing a direct current and an alternating current of 1 to 10 KHz between the first magnet roll 3 and the developing roll 2.

The first magnet roll 3 has (a) the number of magnetic poles of 8 to 32 poles for the equally-spaced multi-pole magnetization, and the magnetic force of the magnetic pole portion is 2
It is constituted by a magnet roll alone magnetized in the range of 50 to 800 Gauss, or (b) a sleeve arranged concentrically with a magnet roll of unequally spaced multipolar magnetism. peripheral speed U ₁ and such that the ratio of the circumferential speed Us of the developing roller 2 is in the range of 1.5 to 4.0, and sets the rotational speed.

The second magnet roll 4 forms a gap (second gap; G ₂ ) with the developing roll 2 and also forms a gap (second distribution gap) with the distribution member 5 that divides the developer. , Is arranged.

The second magnet roll 4 includes a distribution member 5
By attracting the nearby developer 11 and bringing the developer introduced from the gap with the distribution member 5 into rotational contact in the same direction as the developing roll 2, an electric field is applied between the second magnet roll 4 and the developing roll 2. Has the function of applying a toner layer on the developing roll 2. Further, the electric field is the second electric field.
Between the magnet roll 4 and the developing roll 2
It is more desirable to form an alternating current of 0 KHz. The second magnet roll 4 is composed of (a) a magnet roll which is magnetized in a range of 8 to 32 poles and a magnetic force of 250 to 800 gauss, or (b) ) A sleeve is arranged concentrically with a magnet roll of unequally spaced multi-pole magnetized, and the ratio of the circumferential speed U _{2 of} the second magnet roll 4 to the circumferential speed Us of the developing roll 2 is 1.0. The rotation speed was set so as to fall within the range of 3.0 to 3.0.

A scraper 10 is disposed on the toner hopper 6 side of the second magnet roll 4 so as to scrape off the developer after the operation of applying the toner layer onto the developing roll 2 is performed. ing.

The first distribution gap g ₁ formed by the first magnet roll 3 and the distribution member 5 is equal to the second distribution gap g formed by the second magnet roll 4 and the distribution member 5.
₂ is set to be equal to or smaller than 2, the magnetic force of the distribution portion of the second magnet roll 4 is configured to be stronger than the magnetic force of the distribution portion of the first magnet roll 3, and the second magnet roll 4 is
The developer 11 near the distribution member 5 is sucked, and the developer can be introduced from the gap (second distribution gap) with the distribution member 5.

Incidentally, the magnetic force of the distributing portion of the second magnet roll 4 is sufficiently stronger than the magnetic force of the distributing portion of the first magnet roll 3, so that the developer can be distributed without providing the distributing member 5, and the second magnetic roll can be provided. When the distribution member 5 can be introduced to the side, the distribution member 5 may be removed. DC bias power supplies 14, 15, 16 are connected to the developing roll 2, the first and second magnet rolls 3, 4, respectively, and apply respective DC voltages. A voltage obtained by superimposing a DC voltage and an AC voltage of 1 to 10 KHz between the developing roll 2 and the photoconductor 1 and between the first and second magnet rolls 3 and 4 and the developing roll 2 are connected to the bias power supplies 14, 15 and 16. Apply between.

As the developer held by the first and second magnet rolls 3 and 4, a developer containing a carrier having a particle size of 20 to 60 μm and a toner having a particle size of 5 to 8 μm was used. the scrapes off the toner remaining on the developing roller 2 after developing the electrostatic latent image on the 1, the first gap G ₁ between the first magnet roller 3 second gap between the second magnet roll 4 narrower set from G _2, and be used iron powder carrier was found to be most desirable. Moreover, further or narrowing the gap G ₁ between the developing roller 2 and the first magnet roll 3, also been found that can be used a resin carrier and a ferrite carrier by further increasing the force and the peripheral speed. The resin carrier has a bulk specific gravity of 1.0 to 1.
6 g / cm ³ , saturated magnetization of 60 to 80 emu / g, spherical and amorphous, and ferrite carrier has a bulk specific gravity of 2.
2 to 2.7 g / cm ³ , saturation magnetization 20 to 70 emu / g
And a substantially spherical one can be used.

Further, a stirring member 9 is provided on the toner hopper 6 side of the first magnet roll 3 so as to mix and stir the developer and the toner. Was good. The stirring member 9 preferably has not only the mixing and stirring ability in the rotation direction but also the ability to move the developer in a direction parallel to the first and second magnet rolls 3 and 4. Specifically, the rotating direction of a rotating member having a screw shape or an inclined fin is switched, or two rotating members whose moving directions are opposite to each other are used.

When such a developing device is applied to an electrophotographic printer, a positively charged organic photoreceptor (O
PC), an electrostatic latent image having a contrast potential of about 450 V is formed on the photoreceptor 1 having a peripheral speed of 100 to 400 mm / sec, and the peripheral speed of the developing roll 2 is about 1 to about 2 times the peripheral speed of the photoreceptor. Further, when a developing bias of 250 to 350 V was applied to the developing roll 2 and reversal development was performed using positively charged toner, an image density of 1.3 to 1.4 (OD) could be secured.

Further, even when long-term printing was performed, filming of the toner on the developing roll 2 did not occur.

(2) Second Embodiment The second embodiment is a case where the developing device of the present invention is applied to a color electrophotographic apparatus in which four image forming units corresponding to each color are arranged. FIG. 2 shows the configuration.

Developing devices 8-1, 8-2, 8-3, 8-4
The developing method of the present invention can be applied to any of the developing devices or all the developing devices. For example, as shown in FIG. 2, when the developing method of the present invention is applied to the developing device 8-1, Will be described below.

A plurality of developing devices 8-1, 8-2, 8-3, and 8-4, each storing a developer corresponding to each color, are connected to a plurality of photosensitive members 1-1, 1-2, 1-3, and 1 respectively. -4, and is exposed in consideration of the transfer timing to the paper 22.
The writing timings of the latent images by 1, 24-2, 24-3, and 24-4 are set, and the respective photoconductors 1-1, 1-2, and
A latent image corresponding to each color is formed on 1-3, 1-4 and developed by a plurality of developing devices 8-1, 8-2, 8-3, 8-4 to form toner images of each color. Transfer 25-
In a color electrophotographic apparatus for sequentially transferring toner images of each color on the paper 22 by using 1,25-2,25-3,25-4, developing devices 8-1, 8-2, 8-3, 8 out of 8-4
-1 to which the developing method of the present invention is applied, and a color image sensor 27 for detecting a toner image of each color.
(Only one location is shown in the figure, but is provided for each photoconductor), and based on the detection values of the color image sensor 27, DC bias power supplies 14 and 15 for the developing roll and the magnet roll are provided. ,
16, an AC bias power supply 17, rotation driving units 18, 19,
In order to control the device 20, a rotation control unit 29, a bias control unit 30, and an image control unit 28 are provided.

A transfer unit 25-is provided around the photosensitive member 1.
Cleaners 26-1, 26-2, and 26-2 for cleaning toner remaining on photoconductors 1-1, 1-2, 1-3, and 1-4 after transfer by 1,25-2, 25-3, and 25-4. 26-3, 26
-4 is disposed, and a fixing unit 31 is disposed behind the transfer unit 25-4 at the final stage to thermally fuse and fix the unfixed image to the sheet 22.

In such a configuration, when a color toner image is formed on the photoreceptor 1 and color printing is performed, at least the electric field between the developing roll and the magnet roll or the peripheral speed ratio is determined based on the developed toner image. Can control a desired amount of toner development on the photoreceptor, and can reduce image density even in long-term printing,
Alternatively, the color image does not deteriorate due to fluctuation.

(3) Third Embodiment The third embodiment differs from the first embodiment in that a forward electric field is applied between the first magnet roll 3 and the developing roll 2. is there. As for the circulation of the developer, similarly to the first embodiment, the developer 11 is conveyed to the vicinity of the distribution member 5 and the developer magnetic brush 53 introduced from the gap (first distribution gap) with the distribution member 5 is moved to the developing roll. It is configured to make rotational contact with 2 in the counter direction.

In such a configuration, the function of sucking and removing the toner layer on the developing roll 2 tends to be slightly reduced, but a forward electric field is applied between the first magnet roll 3 and the developing roll 2. Therefore, it is possible to apply the toner from the first magnet roll 3 to the developing roll 2, and as compared with the first embodiment, the developing amount is increased by the amount provided by the first magnet roll 3. There is an advantage that the total amount of toner applied to the roll 2 can be increased.

Further, as a result, the number of revolutions of the developing roll 2 can be reduced and set to be substantially equal to the peripheral speed of the photosensitive member 1, so that the definition of the image can be improved as compared with the first embodiment. Thus, the effect of reducing the rubbing load on the photoconductor 1 and prolonging the life of the photoconductor was obtained.

(4) Fourth Embodiment As shown in FIG. 3, an impeller 32 is used as a stirring member.
An impeller 32 as a stirring member is arranged closer to the first magnet roll 3 than in the case of the first embodiment. The gap G _a and the impeller 32 and the first magnet roll 3, the developing roller 2 and the first magnet roll 3
Was set to be equal to or about 1/2 of the first gap G ₁ , the effect of preventing image density unevenness from occurring even in long-term printing and reducing fog was observed. this is,
Below the first magnet roll 3, the developer remaining on the developing roll 2 is collected, and a developer having a high toner concentration is held. It is determined that the toner density is averaged, the toner charge is improved, and the weakly charged toner is reduced by being separated from the magnet roll 3 and stirred and mixed with another developer.

(5) Fifth Embodiment FIG. 4 shows a screw auger 33 having a different conveying direction (in the axial direction) instead of the stirring member 9 of the first embodiment.
34 are arranged in two lines. In this example, in the long-term printing, the image density unevenness in the axial direction did not occur, and the effect of further reducing fog as compared with the first example was observed.

(6) Sixth Embodiment A sixth embodiment shown in FIG. 5 is different from the first and third embodiments in that a regulating plate 55 is provided without distributing member 5,
The first gap G ₁ between the magnet roll 3 and the developing roll 2
To the gap G ₀ between the first magnet roll 3 and the regulating plate 55.
The point is that it is narrower. In other words, the relationship between the first gap G ₁ and gap G ₀ is expressed by the following equation (1).

G ₁ <G ₀ (1) In such a configuration, the transport amount of the developer flowing into the first gap G ₁ between the first magnet roll 3 and the developing roll 2 is equal to The gap G between the first magnet roll 3 and the regulating plate 55
It is suppressed to be less than the transport amount of the developer flowing from ₀ ,
Developer becomes surplus flows into the second gap G ₂ between the developing roller 2 and the second magnet roll 4.

As a result, the developer 11 flowing from the gap G ₀ between the first magnet roll 3 and the regulating plate 55 is distributed to the first magnet roll 3 and the second magnet roll 4.

If the second gap G ₂ is too wide, the contact between the developer magnetic brush 54 and the developing roll 2 becomes insufficient, so the range of the following equation (2) is desirable.

G ₂ ≦ G ₀ −G ₁ (2) In this embodiment, the first and second magnet rolls 3 and 4 are used.
There is no need to dispose the distribution member 5 in the middle part of the first embodiment, and there is an advantage that the structure of the developing device is simplified as compared with the first and third embodiments.

Further, under the first magnet roll 3, the developer remaining on the developing roll 2 is collected and a developer having a high toner concentration is held. The developer held in the step is restricted by the regulating plate 55 and a part thereof flows near the stirring member 9. As a result, the toner-rich (high toner concentration) developer is stirred and mixed with the developer (low toner concentration) flowing down the scraper by the stirring member 9, so that the toner concentration is averaged and the toner charge is good. , And the amount of weakly charged toner decreases, so that image density unevenness does not occur even in long-term printing, and the effect of reducing fog is accompanied.

[0052]

According to the developing device of the present invention, toner filming does not occur on the developing roll even in long-term printing using a low-temperature fixing toner.

Further, in a high-speed color electrophotographic apparatus to which the developing device of the present invention is applied, a change in image density can be prevented, so that a clear color image can be stably secured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a color electrophotographic apparatus according to another embodiment of the present invention.

FIG. 3 is a partial sectional view of a developing device according to another embodiment of the present invention.

FIG. 4 is a partial sectional view of a developing device according to another embodiment of the present invention.

FIG. 5 is a sectional view of a developing device according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 2 ... Developing roll, 3 ... First magnet roll, 4 ... Second magnet roll, 5 ... Distributing member, 6
... toner hopper, 7 stirring blades, 8, 21 ... developing device, 9 ... stirring member, 10 ... scraper, 11 ... developer,
12: toner layer, 13: opening, 14, 15, 16 ... DC bias power supply, 17 ... AC bias power supply, 18, 19,
Reference numeral 20: rotation drive unit, 22: paper, 23: charger, 24-
1 exposure, 25-1 transfer device, 26-1 cleaner, 2
7: color image sensor, 28: image controller, 29: rotation controller, 30: bias controller, 31: fixing device, 32 ...
Impeller, 33, 34 ... screw auger, 53, 54 ...
Developer magnetic brush, 55 ... regulating plate.

Continuation of the front page (56) References JP-A-62-192772 (JP, A) JP-A-60-179766 (JP, A) JP-A-7-92814 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G03G 15/08

Claims (16)

(57) [Claims] A developing roller having a toner layer formed on a surface thereof in contact with a photosensitive member to perform development, wherein the developing roller has a structure in which an elastic roller is fitted to a metal sleeve; And first and second magnet rolls are rotatably provided, and the first magnet
Developing the roll against the second magnet roll
A distribution member is provided on the upstream side in the rotation direction of the roll, a distribution member is provided at an intermediate portion between the first and second magnet rolls, and a developer containing toner and a carrier held by the first magnet roll is supplied to the second magnet. The developer held in the first and second magnet rolls is brought into contact with the developing roll, and the first magnet
Between the developing roll and the developing roll.
In the direction of attracting the toner to the first magnet roll.
The second magnet roll and the developing
Toner on the second magnet roll between the second magnet roll
Act on the developing roll in a direction to move the developing roll ,
A developing device, wherein a toner layer is formed on the developing roll. 2. A developer held by the first magnet roll is brought into contact with the developing roll in a counter direction, and a developer held by the second magnet roll is brought into contact with the developing roll in the same direction. Claim 1 characterized by the following:
The developing device as described in the above. 3. The apparatus according to claim 1, wherein the magnetic force of the second magnet roll is set to be larger than the magnetic force of the first magnet roll at an intermediate portion between the first and second magnet rolls. Developing device. 4. The apparatus according to claim 1, wherein a first gap formed by said developing roll and said first magnet roll is set smaller than a second gap formed by said developing roll and said second magnet roll. The developing device according to claim 1. 5. The developing device according to claim 1, wherein a ratio between a peripheral speed of said second magnet roll and a peripheral speed of said developing roll is set to 1.0 to 3.0. 6. The developing device according to claim 1, wherein said developer is a developer containing an iron powder carrier having a particle size of 20 to 60 μm and a toner having a particle size of 5 to 8 μm. 7. The developing device according to claim 1, wherein the bias voltage applied to the developing roll is obtained by superimposing a DC voltage and an AC voltage. 8. A developing device for performing development by bringing a developing roll having a toner layer formed on its surface into contact with a photoreceptor, wherein the developing roll is configured by fitting an elastic roll to a metal sleeve, and is provided in proximity to the developing roll. And first and second magnet rolls are rotatably provided, and the first magnet
Developing the roll against the second magnet roll
A distribution member is provided at an intermediate portion between the first and second magnet rolls, and a developer containing toner and a carrier held by the first magnet roll is disposed on the upstream side in the rotation direction of the roll. so as to distribute the roll, the developer held on the first magnet roll is brought into contact with the developing roller and the counter direction, the said second of said developer roll developer held on the magnet roll <br /> is contacted in a direction, the first and second the magnet between the developing roller and the first and second magnet roll
A developing device, wherein an electric field is applied in a direction to move toner on the trawl to the developing roll to form a toner layer on the developing roll. 9. A developing device for performing development by bringing a developing roller having a toner layer formed on its surface into contact with a photoreceptor, wherein the developing roller is constituted by an elastic roller, and the developing roller is disposed below the developing roller. the close
One magnet roll is arranged rotatably, and
The developing roll is provided above the first magnet roll.
The second magnet roll is rotatably arranged close to
Then, the first magnet roll adsorbs and pumps the developer and distributes the developer to the second magnet roll, and a gap is provided between the first magnet roll and the development roll.
The toner on the developing roll is transferred to the first magnet roller.
An electric field in the direction of suction is applied to the second magnet
The second magnet between the developing roll and the developing roll.
Transfer toner on the developing roll to the developing roll
A developing device , wherein a toner layer is formed on the developing roll by applying an electric field in a direction of the developing roller. 10. A developing device for performing development by bringing a developing roller having a toner layer formed on its surface into contact with a photoreceptor, wherein the developing roller has a structure in which an elastic roller is fitted to a metal sleeve, and a lower part of the developing roller. the proximate to the developing roll to the side
One magnet roll is arranged rotatably, and
The developing roll is provided above the first magnet roll.
The second magnet roll is rotatably arranged close to
And a regulating portion to which the first magnet roll around the first magnet roll to regulate the amount of the developer pumping adsorbed provided, and the gap G ₀ of the regulating portion, the said first magnet roll a first gap G ₁ is formed by a developing roll, the second gap G ₂ and is formed in the second magnet roll and the developing roll satisfies the following (1) and (2) the relationship And distributing the developer pumped by the first magnet roll to the second magnet roll, between the first magnet roll and the development roll.
The toner on the developing roll is transferred to the first magnet roller.
An electric field in the direction of suction is applied to the second magnet
The second magnet between the developing roll and the developing roll.
Transfer toner on the developing roll to the developing roll
A developing device , wherein a toner layer is formed on the developing roll by applying an electric field in a direction of the developing roller. G ₁ <G ₀ ... (1) G ₂ ≦ G ₀ −G ₁ ... (2) 11. The developer held by the first magnet roll is brought into contact with the developing roll in a counter direction, and the developer layer held by the second magnet roll is brought into contact with the same direction as the developing roll. The developing device according to claim 10, wherein: 12. The magnetic force of the second magnet roll is set to be larger than the magnetic force of the first magnet roll at an intermediate portion between the first and second magnet rolls. Developing device. 13. The second gap G formed by the first of the first gap G ₁ is formed by the magnet roll and the developing roll second magnet roll and the developing roll
11. The developing device according to claim 10, wherein the developing device is set to be smaller than ₂ . 14. The developing device according to claim 10 , wherein a ratio between a peripheral speed of said second magnet roll and a peripheral speed of said developing roll is set in a range of 1.0 to 3.0. 15. The developer has a particle size of 20 to 60 μm.
11. The developing device according to claim 10, wherein a developer containing an iron powder carrier of m and a toner having a particle size of 5 to 8 [mu] m is used. 16. The developing device according to claim 10, wherein the bias voltage applied to the developing roll is obtained by superimposing a DC voltage and an AC voltage.