JP2000056566A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the stabilization of electrification of toner or the prevention of carrying unevenness by an auger and prevent the toner contamination or ground fog on an image by forming a space for holding an excessive developer between a developer regulating member and the magnetizing position of a catching magnetic pole on the circumference of a developer carrier. SOLUTION: A developing device 7 comprises a developer circulating member 43 for circulating a developer quantity regulating member 25 on the circumference of a first developing roller 23, to the vicinity of the pickup magnetic pole N2 of a magnet roll 29 situated on the upper stream of the developer quantity regulating member 25, and forming a space 42 for holding an excessive developer 21 between the developer quantity regulating member 25 and the magnetizing position of the pickup magnetic pole N2 on the circumference of the first developing roller 23. The developer circulating member 43 is formed of a curved part formed continuously to a circular part and largely curved with a curvature radius larger than the circular part and a linear part formed continuously to the lower end of the curved part and substantially in parallel to the surface of the first developing roller 23.

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 for an image forming apparatus such as an electrophotographic copying machine or a printer, and more particularly to a developing device suitable for a highly productive image forming apparatus. .

[0002]

2. Description of the Related Art As a developing device used in an image forming apparatus such as an electrophotographic copying machine or a printer, there is a developing device using a two-component developer composed of a toner and a carrier as magnetic particles. In the developing device in which the two-component developer is opened, the toner is consumed by developing the electrostatic latent image formed on the photosensitive drum, so that the toner is supplied to the developing device main body at a predetermined timing. Is configured. In this developing device, the toner replenished inside the device main body is used immediately for development, thereby preventing surface quality fluctuation such as density unevenness from occurring and maintaining the image quality stably. A member that reliably kneads and conveys the toner replenished inside the printer with the developer housed inside the apparatus main body is used.

[0003] Recent developing devices have been miniaturized, that is, flattened relatively in height and wide in accordance with miniaturization of image forming apparatuses such as copying machines. A member called an auger with spiral blades is generally used as a member for reliably kneading and conveying the toner supplied inside the apparatus main body with the developer contained in the apparatus main body together with the flattening. Is coming. In such a developing device, the toner supplied from the end of the device main body by the auger was kneaded while being conveyed while being rotated together with the developer, and the initial toner charging was performed, and this charging was performed. The developer in which the toner is kneaded is configured to be supplied to a developing roll by a developer supply member. The developer supplied to the developing roll is attracted to the surface of the sleeve of the developing roll by the magnetic force of the magnet roll disposed inside the developing roll, and the developing agent facing the photosensitive drum is rotated with the rotation of the developing sleeve. Conveyed to the area. At this time, the height of the spike of the developer conveyed to the developing area with the rotation of the developing sleeve is regulated by the developer amount regulating member arranged on the upstream side of the developing area. The surplus developer whose height is regulated by the developer amount regulating member is captured again by the magnetic force (pickup pole) of the magnet roll located on the upstream side of the developer amount regulating member. The developer is stably supplied to the upstream side of the toner, thereby stabilizing the chargeability of the toner and preventing uneven conveyance by the auger.

[0004]

However, the prior art described above has the following problems. That is, in the developing device configured as described above, when the developer has good fluidity, or when the developing unit of the developing device is facing the ceiling side of the apparatus main body, the developer amount regulating member restricts spikes. The developer is easily dropped to the developer supply means side due to the action of gravity, and it is difficult for the developer to be captured again by the pickup pole of the magnet roll. The developer cannot be sufficiently circulated between these positions, so that stabilization of the chargeability of the toner and prevention of transport unevenness due to the auger are not sufficiently achieved. When a so-called auger mark appears in which the density of an image appears, or when a small amount of toner existing in the toner is supplied from the toner supply device. Chromatography mass Toner (also referred to as toner grit) soft block is not completely crushed is of, by being directly conveyed to the developing unit, toner contamination or background fog is disadvantageously or generated on the copy.

Further, in the above-mentioned developing device, generally, between the developer amount regulating member and the developing area, in order to prevent the toner in the developer from being scattered to the outside from the opening of the main body of the device,
Although a film-shaped sealing member is provided, the floating toner adheres to the inner surface of the sealing member, and the toner adhered and deposited on the inner surface of the sealing member sometimes falls on a developing roll and is developed as it is. By being transported to the department
There has been a problem that toner smear and background fogging occur on the copy.

Therefore, of these problems, the former cannot sufficiently circulate the developer between the developer amount regulating member and the position of the pickup pole of the magnet roll on the outer periphery of the developer carrier. As a technology that can solve the problem of toner contamination and background fogging on a copy due to unstable charging of toner and conveyance unevenness due to auger, it is difficult to solve the problem. JP-A-62-267783,
JP-A-1-150180, JP-A-3-56947
And Japanese Patent Application Laid-Open No. 3-102377.

The developing device disclosed in Japanese Patent Application Laid-Open No. 62-277783 has a developing sleeve rotatably provided on a side of an electrostatic latent image carrier, and a developer supply means for supplying a developer to the developing sleeve. And a head height regulating member that opposes the upper portion of the developing sleeve and adjusts an amount of developer conveyed to a developing area in which the electrostatic latent image carrier and the developing sleeve face each other;
Inside the developing sleeve, the magnetic poles extending in the axial direction are arranged in the circumferential direction, and the magnetic poles located in the vicinity of the portion facing the ear height regulating member are weak magnetic poles having weak magnetic force, and are located on both sides thereof. And a plurality of magnets which are magnetized to polarities different from those of the weak magnetic poles and have strong magnetic poles.

The developing device disclosed in Japanese Patent Application Laid-Open No. 1-150180 has a sleeve which is rotatable and has a magnet roll therein, a developer reservoir for supplying a developer to the sleeve, and a developing sleeve. A mesh member provided over the entire width in the axial direction of the sleeve, and a toner tank for replenishing the developer reservoir with toner, and a plurality of openings larger than the mesh opening are provided in the upper part of the mesh member in the axial direction of the sleeve. It is configured as follows.

Further, the developing device of the electrophotographic copying machine according to the above-mentioned JP-A-3-56947 is constructed such that the lower end of a baffle plate provided between the stirring member and the developing roll is bent toward the developing roll. Things.

Further, the developing device according to claim 7 of JP-A-3-102377 has a plurality of magnetic poles, adsorbs a developer according to a magnetic field formed between the magnetic poles, and develops a developing area. The developer carrier 1 that transports the developer along a predetermined path and then removes the developer, mixes and agitates the developer that has been released from the developer carrier 1 and the replenishment toner, and mixes and agitates the developer. A stirrer 2 for supplying the developer to the developer carrier 1, a trimming plate 3 provided with a predetermined gap from the developer carrier 1 to uniform the layer thickness of the conveyed developer, The developer carrier 1 and the trimming plate 3 are disposed with a predetermined gap in parallel with the axial direction thereof. In combination with these, the developer separated from the developer carrier 1 by the trimming plate 3 is filled and flows. Helping It is obtained by configured with a back plate 4 to form a deposition zone.

However, in the case of the various techniques according to the above proposals, particularly, in the case of the developing device according to claim 7 of Japanese Patent Application Laid-Open No. 3-102377, the developer carrier 1 and the trimming plate 3 are fixed to a predetermined position. A back plate 4 is provided in parallel with the axial direction with a gap, and together with these, forms an auxiliary suction area in which the developer separated from the developer carrier 1 by the trimming plate 3 is filled and flows. The rear plate 4 is formed of a flat plate arranged in a vertical direction, and the rear plate 4 has an effect of filling the developer separated from the developer carrier to some extent. However, the developer cannot be sufficiently circulated between the developer carrier and the trimming plate, stabilizing the chargeability of the toner and preventing transport unevenness due to the auger. Instead, a so-called auger mark appears in which the density of an image appears in accordance with the pitch of the auger spiral, or when a toner is supplied from a toner supply device, the toner software is a fine lump of toner existing in the toner. The block (also referred to as a toner grit) is not completely crushed, but is conveyed to the developing unit as it is, so that the problem that toner smear or background fogging occurs on a copy cannot be sufficiently solved.

In particular, when the developing section of the developing device faces the ceiling side of the main assembly of the apparatus, the developer supply means for supplying the developer to the developer carrier is not provided obliquely to the side of the developer carrier. Since it is located substantially below, it is almost impossible to hold the developer between the developer supply means and the developer carrying member. Even if it has the effect of filling the developed developer to some extent, the developer separated from the developer carrier drops downward due to its weight, and the developer is sufficiently removed between the developer carrier and the trimming plate. In other words, the so-called auger mark appeared, in which the density of the image appeared corresponding to the pitch of the auger spiral without sufficiently stabilizing the chargeability of the toner and preventing transport unevenness due to the auger. When the toner is supplied from the toner supply device, the toner soft block (also referred to as toner grit), which is a minute lump of toner in the toner, is not completely crushed, and is conveyed to the developing unit as it is. However, it cannot solve the problem that the toner is stained and the background is fogged.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to reduce the space of a developing device along with the miniaturization of an image forming apparatus. Even in a device in which an opening serving as a development region is located at an upper portion, excess developer regulated by the developer amount regulating member is sufficiently circulated between the developer carrier and the developer amount regulating member. It is possible to sufficiently achieve the stabilization of toner chargeability and the prevention of transport unevenness due to the auger, and the occurrence of so-called auger marks, toner stains and background fog on images by breaking toner grit. It is an object of the present invention to provide a developing device which can prevent the occurrence of the developing device.

Another object of the present invention is to prevent the occurrence of toner contamination and background fogging on an image due to the adhesion of floating toner to the inner surface of a sealing member for sealing an opening of a developing device. It is to provide a possible developing device.

[0015]

According to the first aspect of the present invention,
In order to solve the above-mentioned problems, a magnetic member having a plurality of magnetic poles is fixedly disposed inside, and the two-component developer contained in the apparatus main body is transported to a development area while being held on the surface. In a developing device including a developer carrying member and a developer regulating member that regulates an amount of the developer held on the surface of the developer carrying member, an excess developer regulated by the developer regulating member is removed. The developer is circulated to the vicinity of the capture magnetic pole in the developer carrier disposed on the upstream side of the developer regulating member, and the excess developer is attached to the outer periphery of the developer carrier and adheres to the developer regulating member and the capture magnetic pole. A developer circulating member that forms a space to be held between the magnetic position is provided.

Further, in the invention described in claim 2, the developer circulation member is such that the distance from the developer carrying member is wider on the developer regulating member side and gradually approaches the magnetization position side of the capture magnetic pole. 2. The developing device according to claim 1, wherein the developing device is formed in a curved shape so as to be narrow.

Further, the invention according to claim 3 is characterized in that the developer circulation member is formed integrally with the developer regulating member or by adding a further member. Item 3. The developing device according to Item 2.

According to a fourth aspect of the present invention, a magnetic member having a plurality of magnetic poles is fixedly disposed inside, and the two-component developer contained in the apparatus main body is held on the surface. In a developing device comprising: a developer carrier conveyed to a development area; and a developer regulating member for regulating an amount of developer held on a surface of the developer carrier, a developer downstream side of the developer regulating member. A seal member provided on the upstream side of the developing area to prevent toner in the developer from scattering from the opening of the apparatus main body; and a seal member on the inner surface side of the seal member and the developer. A film-like shielding member for preventing toner from adhering to the inner surface of the seal member is provided on the outer periphery of the carrier.

[0019]

According to the above technical means, the invention according to the first aspect captures the excess developer regulated by the developer regulating member in the developer carrier disposed upstream of the developer regulating member. And a developer circulating member that forms a space on the outer periphery of the developer carrier and that holds the excess developer between the developer regulating member and the magnetized position of the capture magnetic pole. With this configuration, the excess developer regulated by the developer regulating member is circulated by the developer circulating member to the vicinity of the capture magnetic pole in the developer carrier disposed on the upstream side of the developer regulating member. Let me
The developer that can be held to some extent in the space formed between the developer regulating member and the magnetized position of the capture magnetic pole on the outer periphery of the developer carrier, and the excess developer is transported to the developing area. And sufficiently achieve stabilization of toner chargeability and prevention of transport unevenness due to auger,
Further, by breaking the toner grit, it is possible to prevent the occurrence of a so-called auger mark and the occurrence of toner stain and background fog on an image.

According to a fourth aspect of the present invention, there is provided a film-shaped shielding member on the inner surface side of the seal member and on the outer periphery of the developing roll for preventing toner from adhering to the inner surface of the seal member. Because it is configured to provide
By the film-shaped shielding member, it is possible to prevent floating toner from adhering and accumulating on the inner surface of the seal member, and the toner adhering and accumulating on the inner surface of the seal member falls onto the developing roll, By being conveyed to the developing section as it is, it is possible to reliably prevent toner stains and background fog on the image.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of an electrophotographic copying machine having high productivity as an image forming apparatus to which the developing device according to the present invention is applied.

In this electrophotographic copying machine, as shown in FIG. 2, originals (not shown) are fed one by one onto a platen glass 3 by an automatic document feeder 2 arranged at an upper portion of a copying machine main body 1. The image of the document is scanned and exposed on a belt-shaped photoconductor 5 by a scanning optical system 4. Prior to the image exposure, the belt-shaped photoconductor 5 is uniformly charged to a predetermined potential by the primary charger 6 and then the image is exposed as described above, and an electrostatic latent image corresponding to the image of the document is formed. It is formed. The electrostatic latent image formed on the belt-shaped photoconductor 5 is
The image is selectively developed by the first or second developing device 7 or 8. Here, as the first and second developing devices 7 and 8, for example, the first developing device 7 performs development with black toner, and the second developing device 8 performs color toner such as red and blue. Is used. Then, the toner image developed on the belt-shaped photoconductor 5 is transferred onto a transfer sheet of a predetermined size fed from a sheet feeding device 10 by a transfer unit 9, and then fixed by a fixing device 11. Are sequentially sent to the sorter 12. In FIG. 2, reference numeral 13 denotes a toner box disposed above the developing device 7, and a supply pipe (not shown) for supplying toner from the toner box 13 to at least one of the developing devices 7 and 8, for example, the developing device 7. To be supplied via the Internet.

FIG. 1 shows a developing device according to an embodiment of the present invention. Although this developing device is used as, for example, a first developing device of the electrophotographic copying machine configured as described above, it goes without saying that the second developing device may have the same configuration. is there.

The developing device 7 is a developing device that uses a black two-component developer, and develops an electrostatic latent image formed on the belt-shaped photosensitive member 5 by a magnetic brush developing method. . The developing device 7 is roughly divided into a device housing 20 and a two-component developer 21 composed of a black toner and a carrier housed inside the device housing 20.
And first and second developing rolls 23 and 24 as a developer carrier disposed in the opening 22 of the apparatus housing 20.
A developer amount regulating member 25 disposed on the side of the first developing roller 23; a paddle 26 disposed below the first developing roller 23 as a developer supply unit; And first and second screw augers 27 and 28 as developer conveying means disposed obliquely below the developing rolls 23 and 24.

As shown in FIG. 1, the device housing 20 is formed of a metal such as aluminum, and the other portion is formed of a synthetic resin formed so as to cover the metal portion. In order to reduce the size as a whole, it is formed in a flat shape having a relatively low height and a wide width. The device housing 20 is provided with an opening 22 over substantially the entire upper end portion. Since the developing device 7 is disposed at an inclined position of the belt-shaped photoconductor 5, the opening 22 is provided. The belt-shaped photoreceptor 5 is formed so as to be inclined in accordance with the inclination.

The opening 2 of the device housing 20
2, first and second developing rolls 23 and 24 are arranged in parallel with each other.
Is partially exposed from the opening 22 of the device housing 20. The first and second developing rolls 23 and 24 have a plurality of magnetic poles, and are magnet rolls 29 and 30 as magnetic members arranged in a fixed state.
A developing sleeve 31 rotatably fitted on the outer circumference of these magnet rolls 29 and 30 in the direction of the arrow.
32.

The magnet roller of the first developing roll 23
As shown in FIG.
In the counterclockwise direction, the magnetic pole S₁, N₁, S_Two,
N_Two, S _Three, N_Three, S_FourIs the magnetizing force at each predetermined position
Have been. Of these magnetic poles, magnetic pole N_TwoThe paddle
The developer scraped up by 26
Magnetic pole for pickup to be attached to the surface of
With the magnetic pole N_ThreeAre magnetic poles for development. Ma
The magnetic poles of the same polarity of the magnet roll 29 are adjacent to each other.
Magnetic pole S_FourAnd S₁On the surface of the first developing roll 23
The held developer 21 is transferred to the second developing roll 24 side.
It is a magnetic pole for separation for transfer. Magnet
Each magnetic pole S of troll 29₁, N₁, S_Two, N_Two, S_Three,
N_Three, S_FourIs not particularly limited.
Is set, for example, as shown in FIGS. This
Here, magnetic pole N for pickup_TwoCaptures developer 21
And the developer circulation member 43 as described later.
Circulating the developer 21 between the developer amount regulating member 25
The intensity at the peak position is flat to enhance the effect
Is set widely.

On the other hand, the magnetic force of the second developing roll 24
As shown in FIG.
Along the counterclockwise direction from the₁, N₁,
S_Two, N _Two, S_Three, N_ThreeIs the magnetizing force at each predetermined position
Have been. Of these magnetic poles, magnetic pole S₁, N₁Is
The developer 21 transferred from the first developing roll 23 is
A magnetic pole for capturing on the surface of the second developing roll 24;
And the magnetic pole S_TwoBecomes a magnetic pole for development
I have. The same polarity magnetic pole of the magnet roll 30 is used.
Is adjacent to magnetic pole S_ThreeAnd S₁Is the second developing roll 24
Once the developer 21 held on the surface of the
For mixing and stirring with the developer 21 in the housing 20.
It is a magnetic pole for peeling. The above magnet roll 30
Each magnetic pole S₁, N₁, S_Two, N_Two, S_Three, N_Three, S_Fourof
The magnetic strength is not particularly limited, for example,
The settings are made as shown in FIGS.

Further, a developer amount regulating member 25 for regulating the amount of the developer 21 captured on the surface of the first developing roll 23 is disposed beside the first developing roll 23. I have. The developer amount regulating member 25 is screwed to the apparatus housing 20 so that the front end thereof faces the surface of the developing roll 23 via a predetermined gap.
Further, the upstream side surface 25 of the developer amount regulating member 25
“a” is formed in a substantially arc-shaped curved shape.

Further, below the first developing roll 23, the developer 2 contained in the apparatus housing 20 is provided.
A paddle 26 is disposed as a developer supply unit that supplies the developer 1 to the first developing roll 23. This paddle 26
Is formed of, for example, a metal such as aluminum,
Many blades 3 formed into a shape bent from the middle
4, and is configured to be driven to rotate in the direction of the arrow so as to scrape up the developer 21 contained in the apparatus housing 20 and supply the developer 21 to the surface of the first developing roll 23. I have.

On the back side of the paddle 26, first and second screw augers 27 and 28 as developer conveying means are arranged in parallel with each other. These first and second screw augers 27, 28
As shown in the figure, the rotary shaft is composed of rotating shafts 35 and 36 arranged in the center thereof along the longitudinal direction, and screw blades 37 and 38 integrally formed in a spiral shape on the outer periphery thereof.

As shown in FIG. 7, toner is supplied from a toner supply device (not shown) to one end 39 (shaded portion) of the second screw auger 28 at a predetermined timing. The toner supplied to one end of the second screw auger 28 is transferred to the developer 21 agitated and conveyed by the second screw auger 28.
At the same time, the developer 21 is immediately delivered to the first screw auger 27 side, and is agitated with the developer 21 contained in the apparatus housing 20 while being transported by the first screw auger 27 in the direction of the arrow. It has become. The developer conveyed to the other end of the first screw auger 27 is transferred to a second screw auger 28 and circulated by the second screw auger 28 in the direction of the arrow. During the transfer, the developer 21 is sufficiently stirred with the developer 21 contained in the apparatus housing 20.

The second screw auger 28
As shown in FIG. 1, the outer periphery of is separated from the inside of the device housing 20 by a partition wall 40, and the developer 21 conveyed by the second screw auger 28 is separated from the developer 21 in the device housing 20. It is configured not to be mixed.

Further, in the developing device 7, at the downstream end of the opening 22 provided in the device housing 20,
A catch-up roll 41 for capturing a carrier attached to the surface of the belt-shaped photoconductor 5 is rotatably disposed.

In this embodiment, the surplus developer regulated by the developer regulating member is circulated to the vicinity of the capture magnetic pole in the developer carrier disposed on the upstream side of the developer regulating member. In addition, a developer circulating member is provided which forms a space on the outer periphery of the developer carrying member for holding the surplus developer between the developer regulating member and the magnetized position of the capture magnetic pole.

The developer circulating member is formed in a curved shape such that the distance from the developer carrying member is wider on the developer regulating member side and gradually narrows toward the magnetization position side of the capture magnetic pole. ing.

That is, in the developing device 7 according to the first embodiment, as shown in FIG. 1, on the outer periphery of the first developing roll 23, the magnet roll 29 located upstream from the developer amount regulating member 25 is located. The excess developer 21 regulated by the developer amount regulating member 25 is circulated near the pickup magnetic pole N ₂ , and the excess developer 21 is distributed around the outer periphery of the first developing roll 23 and the developer amount developer circumfluence member 4 to form a space 42 for holding between the magnetized position of the regulating member 25 and the pickup pole N ₂
3 are provided. The developer circulating member 43 is formed of, for example, a synthetic resin or the like.
5, a substantially arc-shaped portion 43a that is continuous with the arc-shaped portion formed on the side surface on the upstream side, and is formed continuously with the arc-shaped portion 43a, and has a larger radius of curvature than the arc-shaped portion 43a. It comprises a curved portion 43b and a linear portion 43c formed continuously at the lower end of the curved portion 43b and formed substantially parallel to the surface of the first developing roll 23.

As shown in FIG. 8, the developer circulating member 43 is formed continuously with the tip of the arc-shaped portion 43a, and the step portion 25b of the developer amount regulating member 25 and the device housing 20 are formed. An upper end supporting portion 43d supported in a state sandwiched between the inner surface and a curved portion 43b and a straight portion 43c;
A back surface integrally formed along the horizontal direction on the back side of the connection position with the support portion, and fixed in a state of being fitted to the convex portion of the support portion 20a formed along the horizontal direction on the inner surface of the device housing 20. The support portion 43e is fixedly disposed on the device housing 20.

In the first embodiment, the case where the developer circulating member 43 is formed separately from the developer amount regulating member 25 has been described.
The developer circulating member 43 may be formed integrally with the developer amount regulating member 25. In this case, for example, the developer circulating member 43 is formed of a metal such as aluminum, but is not limited thereto. The agent circulation member 43 may be formed of a synthetic resin.

As a result, as shown in FIG. 1, the developer circulating member 43 arranges the excess developer 21 regulated by the developer regulating member 25 on the upstream side of the developer regulating member 25. It is circulated to the vicinity of the pickup magnetic pole N ₂ in the first developing roll 23, and the excess developer 2
1 is the outer periphery of the developing roll 23 and the developer regulating member 25
It is configured to form a space 42 to be held between the magnetic pole N ₂ and the pickup magnetic pole N ₂ .

As shown in FIG. 8, the distance between the arc-shaped portion 43a of the developer circulation member 43 and the surface of the developing roll 23 is a, and the distance between the linear portion 43c and the developing roll 23 is b. In this case, for example, a = 16 to 18 mm, b = 1
It is set to be 0 to 12 mm.

In this manner, as shown in FIG. 1, the space 42 near the pickup magnetic pole is narrowed,
By setting the space 42 near 5 wide, a stagnation region of the surplus developer 21 can be formed. Moreover, the developer 21 supplied from the paddle 26 is sufficiently mixed with the surplus developer 21 in the stagnation portion, and then is supplied to the developing area through the developer amount regulating member 25. 7, the first and second screw augers 27, 28
Thus, a good image which is not affected by the transport path can be obtained.

That is, in the case of the developing device 7, as shown in FIG. 7, when the toner in the device housing 20 is consumed, a predetermined amount of toner is supplied from a toner supply device (not shown) to the second screw auger. 28 to one end 39. The toner supplied to one end of the second screw auger 28 is immediately transferred to the first screw auger 27 side together with the developer 21 stirred and conveyed by the second screw auger 28, and the first While being transported along the arrow direction by the screw auger 27, the developer 21 contained in the apparatus housing 20 is agitated. Then, the developer 21 conveyed to the other end of the first screw auger 27 is transferred to the second screw auger 2 this time.
8 and the second screw auger 28
While being conveyed so as to circulate in the direction of the arrow, the developer 21 is sufficiently stirred with the developer 21 accommodated in the apparatus housing 20.

However, the first and second screw augers 27 and 28 have a higher transporting performance than a stirring performance, and the first and second screw augers 2 and
When the developer 21 is agitated and conveyed by the devices 7 and 28, the newly supplied toner is transferred to the developer 2 in the apparatus housing 20.
In some cases, it cannot be sufficiently stirred with 1. For this reason, the toner newly supplied into the housing 20 of the developing device 7 is not sufficiently stirred with the developer 21 in the device housing 20, and thus the toner is not sufficiently charged initially, and
Moreover, the paddle 2 is not sufficiently mixed with the developer 21.
6, there is a possibility that the toner is supplied to the first developing roll 23.

However, even in such a case, the excess amount of the developer 21 adhered to the outer periphery of the first developing roll 23 is regulated by the developer amount regulating member 25,
The developer is circulated by the developer circulating member 43 to the vicinity of the pickup magnetic pole N ₂ of the developing roll 23. At this time, the outer periphery of the developing roll 23 is located in the space 4 near the pickup magnetic pole.
By setting the width 2 to be narrow and the space 42 in the vicinity of the developer amount regulating member 25 to be wide, a stagnation region of the surplus developer 21 can be formed. Therefore, the developer 21 supplied from the paddle 26 is sufficiently mixed with the surplus developer 21 in the stagnation portion, and then is supplied to the developing area through the developer amount regulating member 25. First and second in 7
The developer which is not sufficiently charged or mixed by the screw augers 27, 28, etc. is not transported to the developing area as it is, so that the chargeability to the toner is stabilized and the transport unevenness due to the auger is sufficiently achieved. And so-called auger marks can be prevented from being generated.
In addition, when toner is supplied from the toner supply device, a toner soft block (also referred to as toner grit), which is a fine lump of toner present in the toner, is not completely crushed and is conveyed to the developing unit as it is. The problem that toner smear or background fogging occurs on a copy can be sufficiently solved.

FIG. 15 shows the result of an experiment conducted by the present inventors to confirm the effect of the first embodiment. By providing the developer circulating member 43, copying by a mass of toner is performed. The occurrence rate of the above dirt is about 1/3 of the conventional
It can be seen that it can be reduced to the extent.

Comparative Example 1 FIG. 9 shows a conventional developing device as Comparative Example 1.
Opposing member 5 arranged upstream of the developer amount regulating member 25 such that the distance from the surface of the developing roll 23 is a and b.
0 is provided. In Comparative Example 1, the distance a is set to 16 to 18 mm, and the distance b is set to 16 to 18 mm.

As described above, when the space in the vicinity of the pickup magnetic pole and the space in the vicinity of the developer amount regulating member 25 are both set to be similarly large, the surface of the developing roll 23 and the opposing member 50 in the vicinity of the pickup magnetic pole are set. The distance to the paddle 26 is as long as 16 to 18 mm, and the magnetic force of the magnetic pole for pickup does not reach. Therefore, the surplus developer 21 regulated by the developer amount regulating member 25 is not captured by the magnetic pole for pickup again, and is not To fall. Therefore, the excess developer 21 cannot be sufficiently circulated upstream of the developer amount regulating member 25 to promote the mixing of the developer 21, thereby stabilizing the chargeability of the toner and preventing transport unevenness due to the auger. Cannot be sufficiently achieved, so-called auger marks are generated, and when toner is supplied from the toner supply device, a toner soft block (also referred to as toner grit), which is a minute lump of toner existing in the toner, is formed. It is not possible to sufficiently solve the problem that the toner is contaminated and conveyed to the developing section as it is, thereby causing toner stains and background fogging on the copy.

Comparative Example 2 FIG. 10 shows a developing device as Comparative Example 2.
The developing device includes an opposing member 50 linearly arranged on the outer periphery of the developing roll 23 and upstream of the developer amount regulating member 25 so that the distance from the surface of the developing roll 23 is a and b. I have. In Comparative Example 2, the distance a is set to 12 to 14 mm, and the distance b is set to 10 to 12 mm.

As described above, the distance between the surface of the developing roll 23 and the opposing member 50 in the vicinity of the pickup magnetic pole is reduced by one.
Although the excess developer 21 could be captured again by the pickup magnetic pole by approaching to about 0 to 12 mm, since the space near the developer amount regulating member 25 was also narrowed, the excess amount of developer was It is in a packing state, and the development cannot be performed if it is good.

Second Embodiment FIGS. 11 and 12 show a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals and described. In the second aspect, on the downstream side of the developer regulating member and on the upstream side of the developing area,
A seal member provided to prevent toner in the developer from scattering from the opening of the apparatus main body; and an inner surface of the seal member on the inner surface side of the seal member and on the outer periphery of the developer carrier. And a film-shaped shielding member for preventing toner from adhering to the film.

That is, in the second embodiment, FIG.
And a housing 20 of the developing device 7 as shown in FIG.
A film-like sealing member 60 is provided at the upstream end of the opening 22 to prevent the floating toner from leaking out of the apparatus from the upstream end of the opening 22.
Is provided. The seal member 60 is formed, for example, from a polyurethane rubber into a film having a thickness of 100 μm. The seal member 60 is attached to a metal plate 61 attached to an end of the apparatus housing 20 on the upstream side of the opening 22 with the base end 60a fixed. The metal plate 61 has a base end 61a.
Side is attached so as to form an acute angle with respect to the belt-shaped photoreceptor 5, and an intermediate portion 61b thereof
Are bent substantially parallel to the belt-shaped photoreceptor 5, and the front end 61c is bent inward so as to keep a predetermined distance from the surface of the developing roll 23.

Further, in the second embodiment, a film-shaped shield for preventing toner from adhering to the inner surface of the seal member 60 on the inner surface side of the seal member 60 and on the outer periphery of the developer roll 23. A member 62 is provided. As shown in FIG. 12, the film-shaped shielding member 62 is attached with its intermediate portion 62b adhered to the distal end portion 61c of the metal plate 61, and its base end portion 62c.
a is extended so as to reach the developer amount regulating member 25, and the tip end 62c is
Before reaching the surface of the photoreceptor 5, it is extended to reach the surface of the belt-like photoreceptor 5.

In the second embodiment, in the operating state, as shown in FIG. 12, the tip 60c of the seal member 60 comes into contact with the surface of the belt-shaped photoconductor 5, and It deforms following the surface of No. 5. Further, the film-shaped shielding member 62 comes into contact with the inner surface of the deformed sealing member 60 and
It is designed to be curved at a substantially constant distance from the surface.

In the second embodiment, FIGS.
As shown in FIG. 3, a film-shaped shielding member 62 for preventing toner from adhering to the inner surface of the seal member 60 is provided on the inner surface side of the seal member 60 and on the outer periphery of the first developing roll 23. With this configuration, the developer that has passed through the developer amount regulating member 25 becomes a spike-shaped magnetic brush by the magnetic poles of the developing roll 23 and rubs the surface of the film-shaped shielding member 62. .

For this reason, the film-shaped shielding member 62
Accordingly, it is possible to directly prevent the floating toner from adhering and depositing on the inner surface of the seal member 60 and also prevent the floating toner from adhering to the surface of the film-shaped shielding member 62. , Sealing member 6
The floating toner adheres to the inner surface of the seal member 60, and the toner adhered to and accumulated on the inner surface of the seal member 60 falls onto the developing roll 23 and is conveyed to the developing unit as it is, so that toner smears and background on the copy are obtained. It is possible to reliably prevent fogging from occurring.

In the second embodiment, as shown in FIGS. 11 and 13, a rectifying plate 70 for adjusting the air flow in the developing device 7 between the second developing roll 24 and the catch-up roll 41. Are provided short in the non-magnetized portions at both ends of the second developing roll 24.

The rectifying plate 70 regulates the air flow in the developing device 7 to prevent the cloud toner from leaking from both ends of the second developing roll 24 to the outside.

Further, in the third embodiment, as shown in FIG. 14, toner is prevented from leaking from both longitudinal ends of the opening 22 to the longitudinal end of the opening 22 of the apparatus housing 20. Therefore, a side film seal member 71 formed of a 200 μm thick film made of polyurethane rubber or the like is provided.

FIG. 15 shows the results of an experiment conducted by the present inventors to confirm the effect of the second embodiment. By providing a film-shaped shielding member 60, the amount of toner It can be seen that the rate of occurrence of dirt on the copy can be reduced to about 2/3 of the conventional level.

Further, by combining the first embodiment and the second embodiment, it can be seen that contamination on the copy due to a lump of toner can be prevented.

[0063]

According to the present invention, the space for the developing device is reduced with the downsizing of the image forming apparatus, and the developing area is reduced. Even in a device in which the opening is located at the top, the excess developer regulated by the developer amount regulating member is
The toner can be sufficiently circulated between the developer carrying member and the developer amount regulating member, stabilizing the chargeability of the toner and preventing transport unevenness due to the auger, and breaking the toner grit to form a so-called auger. It is possible to provide a developing device capable of preventing the occurrence of marks and the occurrence of toner contamination and background fog on an image.

According to the fourth aspect of the present invention, it is possible to prevent the occurrence of toner contamination and background fogging on an image due to the adhesion of the floating toner to the inner surface of the sealing member for sealing the opening of the developing device. A possible developing device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing Embodiment 1 of a developing device according to the present invention.

FIG. 2 is a configuration diagram showing an embodiment of an electrophotographic copying machine as an image forming apparatus to which the developing device according to the present invention is applied.

FIG. 3 is a graph showing a magnetic force distribution of a magnet roll of a first developing roll.

FIG. 4 is a table showing a magnetic force distribution of a magnet roll of a first developing roll.

FIG. 5 is a graph showing a magnetic force distribution of a magnet roll of a second developing roll.

FIG. 6 is a table showing a magnetic force distribution of a magnet roll of a second developing roll.

FIG. 7 is a configuration diagram illustrating a developer conveyance state of first and second screw augers.

FIG. 8 is an enlarged configuration diagram illustrating a main part of the developing device according to the first embodiment of the present invention.

FIG. 9 is a configuration diagram illustrating a developing device of Comparative Example 1.

FIG. 10 is a configuration diagram illustrating a developing device of Comparative Example 2.

FIG. 11 is a configuration diagram showing a developing device according to a second embodiment of the present invention.

FIG. 12 is a configuration diagram showing a main part of a developing device according to a second embodiment of the present invention.

FIGS. 13A and 13B are configuration diagrams showing a developing device according to a second embodiment of the present invention.

FIGS. 14A and 14B are configuration diagrams illustrating a developing device according to a second embodiment of the present invention.

FIG. 15 is a table showing experimental results according to the first and second embodiments of the present invention.

[Description of sign]

5: belt-shaped photoreceptor, 7: developing device, 20: device housing, 21: developer, 23: first developing roll, 25:
Developer amount regulating member, 29: magnet roll, 31: developing sleeve, 43: developer circulation member.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shino Yokoyama 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Inventor Shiro Suzuki 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Inventor Akihito Nishimura 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Hirohisa Hoshino 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. BA08 CA12 EA03 FA19 FA22 FA26

Claims (4)

[Claims] 1. A developer carrying device in which a magnetic member having a plurality of magnetic poles is fixed and disposed inside, and a two-component developer contained in an apparatus main body is transported to a developing area while being held on a surface. And a developer regulating member that regulates the amount of developer held on the surface of the developer carrying member, wherein the excess developer regulated by the developer regulating member is removed by the developing device. While circulating to the vicinity of the capture magnetic pole in the developer carrying member disposed on the upstream side of the developer regulating member, the excess developer is located on the outer periphery of the developer carrying member and the magnetization positions of the developer regulating member and the capturing magnetic pole are determined. A developer circulating member that forms a space held between the developing devices. 2. The developer circulating member is formed in a curved shape such that the distance from the developer carrying member is wide on the developer regulating member side and gradually narrows toward the magnetization position side of the capture magnetic pole. The developing device according to claim 1, wherein: 3. The developing device according to claim 1, wherein the developer circulating member is formed integrally with the developer regulating member or by adding a further member. . 4. A developer carrying device in which a magnetic member having a plurality of magnetic poles is fixed and disposed inside, and the two-component developer contained in the main body of the apparatus is transported to a developing area while being held on its surface. And a developer regulating member that regulates the amount of developer held on the surface of the developer carrying member, wherein the developer regulating member is located downstream of the developer regulating member and upstream of a developing area. A seal member provided to prevent toner in the developer from scattering from an opening of the apparatus main body; and a seal member provided on the inner surface side of the seal member and on the outer periphery of the developer carrier. And a film-shaped shielding member for preventing toner from adhering to the inner surface of the developing device.