JPH05100569A - Developing device - Google Patents

Abstract

PURPOSE:To efficiently uniformize the distribution of developer supplied from an external developer storage box into a developer container and to prevent the occurrence of unevenness in the density of a wide image without making a device large in size. CONSTITUTION:A rotary stirring member 4 for stirring the developer stored in the developer container 6 so as to uniformize the developer is arranged nearly parallel with a developer carrier 1, and a developer replenishment port 8 which is connected with a developer carrying path 9 is installed on the almost central part of a housing 7 in the axial direction of the developer carrier. Thus, the developer supplied to the developer container 6 is transmitted to both left and right end parts in the axial direction of the rotary stirring member, and then, the distribution of the developer can be uniformized in a short time. Thus, the occurrence of the unevenness of the layer thickness distribution of the developer layer formed on the developer carrier can be prevented, so that a good image can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device which is used in an image forming apparatus such as an electrophotographic copying machine or a printer and which makes a developer adhere to an electrostatic latent image for visualization.

[0002]

2. Description of the Related Art Conventionally, a developing device shown in FIG. 8 is known as a developing device for visualizing an electrostatic latent image by attaching a developer thereto. This developing device regulates the amount of developer adhered on the cylindrical developer carrier 101, which rotates in opposition to the electrostatic latent image carrier 102, and the developer carrier, and forms a thin layer of developer. A first developer accommodating chamber 112, which is located adjacent to the developer regulating member 103 and the developer carrying member 101, and accommodates the developer supplied from the hopper 121.
And a developer supply member 104 that supplies the developer from the first developer storage chamber 112 to the developer carrier, and the second developer storage chamber partitioned by the first developer storage chamber 112 and the partition 114. And 113. The first developer accommodating chamber 112 and the second developer accommodating chamber 113 communicate with each other at both ends in the axial direction of the developer carrier, and the first developer conveying member 110 and the first developer conveying member 110 are provided inside thereof. 2 developer conveying member 11
1 and are provided. This first developer transport member 11
0 and the second developer carrying member 111 carry the developer in opposite directions.

In such a developing device, the hopper 1
The developer introduced from 21 into the first developer accommodating chamber 112 is conveyed by the first developer conveying member 110 and the second developer conveying member 111 so as to circulate in the two developer accommodating chambers. , Are evenly distributed in the first developer accommodating chamber in the axial direction of the developer carrier. This developer is supplied to the surface of the developer carrier 101 by the developer supply member 104,
The developer regulating member 103 forms a uniform thin layer. When the developer carrying member rotates, the thinned developer is conveyed to a developing region where the developer carrying member 101 and the electrostatic latent image holding member 102 closely face each other, and is generated in this developing region. The electrostatic latent image holding member 10 causes the developer to develop due to the oscillating electric field.
The latent image is visualized by transferring to the latent image on 2.

In such a developing device, it is possible to use a one-component developer consisting only of toner or a two-component developer formed by mixing toner and magnetic particles, and the axis line of the developer carrying member is used. The developer is uniformly supplied in the direction, and a high-quality toner image without density unevenness can be formed.

However, in the developing device as described above, the developer supplying member and the two developer conveying members must be provided in addition to the developer carrying member, so that the developing device becomes large in size. In particular, in a color image forming apparatus using four developing devices respectively accommodating four color developers, the use of the developing device as described above increases the size of the image forming device. Under such circumstances, a developing device as shown in FIG. 9 has been proposed in order to downsize the developing device.
FIG. 1 is a schematic perspective view showing this developing device, and FIG. 3 (b) is a view showing a cross section of an image to be developed in a direction perpendicular to the width direction.

This developing device does not use a member forcibly conveying the developer in a predetermined direction unlike the developer conveying members 110 and 111 in the above-mentioned conventional example, but the developer is in the axial direction of the developer carrier. A rotary stirring member 24 is provided to evenly distribute the unevenly distributed particles. In such a developing device, the developer carried from the developer storage box 31 to the one end portion in the axial direction of the developer carrier of the developer storage chamber 26 through the developer transport path 32 is
As the rotary stirring member 24 rotates, it is gradually transferred in the axial direction of the rotary stirring member 24. At the same time, the developer is supplied to the developer carrier 21, and the developer adhering to the surface is thinned by the developer regulating member 23. The thinned developer is conveyed to the developing area A by the rotation of the developer carrier 21 and develops the electrostatic latent image 5 on the electrostatic latent image holder 2.

[0007]

However, in the developing device having the above-described structure, the developer is rotated and stirred by the rotary stirring member 4.
Since it is replenished from the axial end of the rotary stirring member 4 and transferred along the axial direction of the rotary stirring member 4, the response of the replenishment of the developer to the consumption of the developer at the opposite end is slow, and the developer accommodating chamber Of the developer tends to be non-uniform. For this reason,
The amount of developer supplied to the developer carrying member becomes non-uniform in the developer carrying member axial direction, causing unevenness in the layer thickness distribution of the developer formed on the developer carrying member, resulting in uneven density in a wide area image. There is a problem that it occurs.

The present invention has been made in view of the above problems, and it is a downsized developing device that efficiently equalizes the distribution of the developer supplied into the developer accommodating chamber, An object of the present invention is to provide an image device capable of preventing the occurrence of density unevenness in a wide area image.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to a developer carrying member which is provided so as to face an electrostatic latent image holding member and which conveys a developer by adhering it to the surface thereof. A developer regulating member that regulates the amount of the developer on the developer carrying member to form a thin layer of the developer is provided in the housing, and the developer carrying member and the electrostatic latent image holding member closely face each other. A developing device for visualizing a developer on the surface of the developer carrier by adhering the developer on the surface of the developer carrier to the electrostatic latent image on the electrostatic latent image carrier in a developing area, wherein the developer is arranged substantially parallel to the axial direction of the developer carrier. And a rotation stirring member that conveys the developer by rotating and stirs the developer stored in the housing to equalize the distribution of the developer in the axial direction of the developer carrier, About the housing in the axial direction of the developer carrier. The central portion, and having a developer supply port to be connected to the tubular developer conveying path.

Further, it is desirable that the rotary stirring member is a tubular member having a plurality of openings on its peripheral surface and is rotatable about the axis of the tubular member.

The developer replenishment port can be located at any position where the developer can be supplied into the housing, such as the upper portion of the housing, the rear wall portion, etc., as long as it is substantially the central portion in the axial direction of the developer carrier. A partition plate that is opened only in the direction toward the inside of the housing is provided at the developer replenishment port that is connected to the cylindrical developer transport path in order to prevent the developer from moving backward into the developer transport path. Is desirable.

[0012]

In the developing device having the above-described structure, the rotating stirring member for equalizing the distribution of the developer is provided, and the developer replenishing port is provided at the central portion of the developer carrier in the axial direction. The developer thus agitated is agitated by the rotary stirring member, and is transferred to the left and right ends in the direction of equalizing the distribution of the developer, that is, the axial direction of the rotary agitator. Therefore, as compared with the case where the developer is supplied from one end, the transfer distance becomes shorter and the transfer time is shortened. For this reason, it becomes possible to replenish the developer to both ends of the rotary stirring member in a short time according to the consumption of the developer, which causes unevenness in the layer thickness distribution of the developer in the axial direction on the developer carrier. Can be prevented. Further, since the developer supply port is connected to the cylindrical developer transport path, the developer storage box can be provided at a position apart from the developing device by extending the developer transport path, It is possible to arrange the developing device in a small space.

In a developing device in which a cylindrical member having a plurality of openings on its peripheral surface is used as a rotary stirring member and is rotated around the axis of the cylindrical member, the developer is replenished into the housing from a developer replenishing port. The developer is efficiently stirred by the rotation of the cylindrical member. Therefore, even if the outer diameter of the rotary stirring member is small, a large amount of the developer can be effectively stirred, and the developer is quickly transferred to the end portion. Therefore,
The effect of preventing uneven distribution of the developer layer thickness formed on the developer carrying member becomes remarkable.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing the structure of a developing device according to a first embodiment of the present invention, FIG. 1 (a) is a perspective view showing the developing device having a developer storage box, and FIG. FIG. 4 is a cross-sectional view of a developed image in a direction perpendicular to the width direction. In this developing device, a cylindrical developer carrier 1 that rotates in opposition to an electrostatic latent image carrier 2 in a housing 7, a developer adhesion amount on the developer carrier, and a developer And the developer regulating member 3 that forms a thin layer of the developer, and the developer is agitated to equalize the distribution of the developer in the axial direction of the developer carrier, and the developer is agitated to the developer carrier 1. And the member 4. Further, the housing 7 is provided with a developer replenishing port 8 on a rear wall portion at a substantially central portion in the axial direction of the developer carrying body 1, and the developer replenishing port 8 is provided on an external developer storage box 11 Is connected via a cylindrical developer carrying path 9. Inside the developer transport path 9, there is provided a developer transport means 10 for replenishing the developer stored in the developer storage box 11 to the developer storage chamber 6 in the housing.

The developer carrying member 1 has a surface on which a developer is attached and can be conveyed by rotating, and an electrostatic latent image holding member 2 capable of holding an electrostatic latent image 5 on the surface.
The position close to is the development area A. A DC bias AC voltage is applied to the developer carrying member 1 from a developing bias power source (not shown), and the developer having a charge due to the electric field formed in the developing area A is electrostatic latent image holding member 2. It is adapted to adhere to the electrostatic latent image 5 above.

The developer carrying member 1 has a diameter of 5 to 40 m.
Ra is approximately m by cutting a round bar or pipe of aluminum or stainless steel and then subjecting the circumferential surface to mechanical processing such as sandblasting, liquid honing or emery polishing, or chemical corrosion.
Those having irregularities of about 0.1 to 1.0 μm are used. Further, the developer carrying member 1 is formed by cutting a round bar or pipe of aluminum or stainless steel, coating the circumferential surface with a semiconductive material such as phenol resin, and further subjecting it to mechanical polishing such as emery polishing. The surface roughness may be Ra = about 0.1 to 1.0 μm, or an aluminum round bar or pipe may be mechanically polished and then anodized to have a predetermined surface roughness. When the developer carrier 1 is coated with a semiconductive material, or when an aluminum round bar or the like is anodized and used, the developer carrier surface layer has a volume resistance in the thickness direction of 10 ⁵ Approximately 10 ¹² Ω · cm. With such a volume resistance, there is an advantage that the leak of the bias voltage applied to the developer carrying member can be suppressed.

As the electrostatic latent image holding member 2, a Se type photosensitive member or an organic photosensitive member is used, and the developer carrying member 1 and the electrostatic latent image holding member 2 have a gap of about 100 to 300 μm. Hold and face. The developer regulating member 3 has a thickness of 0.
03-0.3mm stainless steel leaf spring 3
It is obtained by vulcanizing and adhering Si rubber or EPDM rubber to a, and the contact pressure with the developer carrying member 1 is 20 to 200 g / c.
abut about m. As a result, the developer is 10
It is formed in a thin layer of about 30 μm and has a thickness of 2 to 20.
A charge of about μC / g is applied. The rotary stirring member 4 is
It is supported in the vicinity of the developer carrying body 1 in a developer accommodating chamber 6 provided at a position facing the developer carrying body 1, and rotates in the same direction as the developer carrying body 1.

FIG. 2 is a schematic view showing the rotary stirring member 4, FIG. 2 (a) is a perspective view, and FIG. 2 (b) is a front view and a side view. The rotary stirring member 4 has a diameter of 6 to 30.
A plurality of substantially oval openings 4b are provided by cutting on the peripheral surface of a cylindrical member 4a made of aluminum or stainless steel having a thickness of about 0.5 mm and a thickness of about 0.5 to 2 mm. The openings 4b are linearly arranged along the axial direction of the cylindrical member 4a, and as shown in FIG. 2 (b), the axial length L ₁ of the openings and the distance L between the openings. It is provided that ₂ and ₂ are almost equal. Further, the rows of the holes 4b are provided in four rows at positions distributed by 90 ° in the circumferential direction, and the positions of the holes are ½ of the positions of the holes in the adjacent rows.
They are arranged by shifting the pitch.

The ratio (opening ratio) of the openings to the total circumferential area must be 20 to 70%, and particularly 30 to 60.
It is desirable to be about%. This has an opening rate of 20%
If the ratio is below, the supply of the developer to the developer carrier becomes insufficient, and it becomes necessary to increase the rotation speed of the rotary stirring member 4, and if it is 70% or more, the developer is uniformly distributed in the developer accommodating chamber 6. Dispersion becomes difficult, and uneven density occurs in a black solid image. This tendency was confirmed when the diameter of the rotary stirring member 4 was in the range of 10 to 20 mm. The peripheral surface roughness of the rotary stirring member 4 is preferably 1.5 μRa or less.

Such a rotary stirring member 4 has a clearance of 0.2 to 3.0 mm from the developer carrying member, and 300 to 10
It rotates at a speed of about 00 rpm, and a bias voltage may be applied between the rotary stirring member 4 and the developer carrying member 1 from a developer supplying bias power source (not shown). This bias voltage is for supplying a sufficient amount of developer from the rotary stirring member 4 to the developer carrying member 1. If sufficient developer can be supplied without applying a bias voltage, It is not necessary to connect a bias power source for supplying the developer. When applying a bias voltage, it is necessary to set the volume resistance to 10 ¹⁰ Ω · cm or less even when the rotary stirring member 4 is molded with resin or when a coating layer is applied to metal. The ability of the rotary stirring member 4 to supply the developer to the developer carrying member 1 is almost equal to the outer diameter, the inner diameter, the opening ratio, the rotational speed, the applied bias voltage, and the clearance between the developer carrying member 1 and the rotary stirring member 4. It is controlled by proper selection.

As the developer used in the above-mentioned developing device, a non-magnetic one-component developer, such as a pigment such as carbon or a metal-containing azo dye in various thermoplastic resins such as styrene resin and acrylic resin, is used. It is possible to use a material in which a polarity control agent is dispersed and a size of 5 to 20 μm is obtained by pulverization classification, and a charge control agent is externally added. The charge control agent is
Hydrophobized silica, alumina, titanium etc. 0.1μ
Although fine particles of m or less are used, hydrophobic silica is most preferable.

Further, the developer conveying path 9 connecting the developing device and the external developer storage box 11 is made of a flexible cylindrical member, and the developer conveying means is made of a spiral member having flexibility inside. Have ten. The developer conveying means 10 is operated by a dispense ON signal output from a developer amount detecting means (not shown) when the developer in the developer accommodating chamber 6 is consumed and reduced, and the developer accommodating chamber 10 is operated. It is possible to adjust the amount of developer supplied to the inside. In the present embodiment, the developer amount detecting means detects the developer amount from the value of the current flowing between the rotating stirring member 4 and the developer carrying member 1 when the developer is transferred. Dispense is set to ON when the value falls below a specified value. Further, as the developer amount detecting means, it is possible to use a method of detecting the developer accumulation height in the developer accommodating chamber 6.

Next, the operation of the developing device as described above will be described. The developer carried from the developer storage box 11 outside the developing device to the position facing the rotary stirring member 4 in the developer accommodating chamber 6 through the developer transport path 9 has an opening formed in the rotary stirring member 4. It passes through 4b and is introduced into the inside 4c of the rotary stirring member. Further, the developer is the rotary stirring member 4
Is gradually transferred from the central portion to the axial end portions of the left and right rotary stirring members, and the developer is substantially evenly distributed in the width direction forming an image. At the same time, the rotation of the rotary stirring member 4 causes the developer to be discharged to the outside of the rotary stirring member 4 through a plurality of openings 4b provided in the peripheral surface, and the developer is supported in close proximity to the rotary stirring member 4. Adhesion to the developer carrier 1 is sufficient, and sufficient developer is supplied substantially evenly in the width direction for forming an image. Further, a bias voltage is applied between the rotary stirring member 4 and the developer carrying member 1, which helps to uniformly supply a sufficient amount of the developer.

The developer adhering to the surface of the developer carrying member 1 is rubbed against the surface of the developer carrying member 1 by the developer regulating member 3 to form a uniform thin layer and charged. Further, as the developer carrying member 1 rotates, the thinned developer is conveyed to the developing area A. Here, an oscillating electric field is generated between the developer carrier 1 and the electrostatic latent image carrier 2 by the DC superimposed AC voltage applied to the developer carrier 1.
The charged developer flies and visualizes the electrostatic latent image 5 on the electrostatic latent image holder 2.

In such a developing device, the developer supply port 8
Is provided substantially in the center in the width direction where an image is formed. Therefore, when the distribution of the developer is equalized by the rotary stirring member 4, the transfer distance to the end is short, and it is equalized in a short time. .. Therefore, the developer is stably and uniformly supplied in the axial direction of the developer carrying member 1, the layer thickness distribution of the developer layer formed on the developer carrying member 1 becomes uniform, and the image to be developed is The occurrence of density unevenness is prevented.

Further, in the developing device as described above, the developer supply port 8 to which the developer conveying path 9 is connected is provided with a protrusion 12 as shown in FIG. It is also possible to mount the partition plate 13 configured as described above.
As a result, the developer carried into the developer storage chamber through the developer transport path 9 is prevented from returning to the developer transport path 9 again, and the developer is accurately replenished according to the consumption of the developer. It will be. Therefore, the developer is efficiently transferred to both ends of the rotary stirring member in the developer accommodating chamber, and the uniform distribution of the developer is promoted.

Next, in the developing device as described above, A
The results obtained by developing 20 solid black images on the entire surface of a 3rd printing medium in succession and comparing it with an image by a conventional developing device are shown. FIG. 4 is a diagram showing the image density at each position in the width direction of the image when the image is developed by the developing device of this embodiment in comparison with the image by the conventional developing device shown in FIG. In the image obtained by the conventional developing device, a drastic decrease in image density was observed as the image was transferred from the side where the developer supply port was provided to the end on the opposite side in the axial direction of the rotary stirring member. On the other hand, in the image formed by the developing device of this example, almost no difference in image density was observed at the position in the width direction of the image, and it was confirmed that a good image was obtained.

Further, in the developing device of this embodiment, in order to confirm the effect of equalizing the distribution of the developer in the developer accommodating chamber, a comparison test of the developer transfer time with the conventional developing device shown in FIG. 9 was conducted. It was FIG. 5 is a diagram showing the relationship between the distance over which the developer is transferred toward the end of the developer accommodating chamber and the elapsed time when 40 g of the developer is supplied to the developing device of this embodiment. FIG. 6 is a diagram showing the relationship between the developer transfer distance and the elapsed time in the conventional developing device. In the conventional developing device, it takes about 200 seconds until the developer supplied from one side of the developer accommodating chamber reaches the end portion on the opposite side. It takes only about 90 seconds for the developer supplied from the center of the chamber to reach both ends. As can be understood from this, the developing device according to the present embodiment can supply the developer with high responsiveness to the entire area of the developer carrying member.

FIG. 7 is a schematic view showing the structure of the developing device according to the second embodiment of the present invention. This developing device has the same structure as that of the developing device shown in FIG. 1, but instead of the rotary stirring member 4, a cylindrical developer supply in which convex portions 14a continuous in the axial direction are radially formed on the outer peripheral surface. The paddle 14 is used. In this developer supply paddle 14, the convex portion 14a is brought into pressure contact with the developer carrying member 1, and the convex portion is compressed by about 1 mm by the contact pressure. A bias voltage is applied to the developer supply paddle at a potential on the negative side with respect to the developer carrier 1. Therefore, when the developer supply paddle 14 rotates, the negatively charged developer carried by the convex portion 14a is attracted to the developer carrier 1 by an electric force, and electrostatic force, adhesive force, van der Waals force, etc. Held by When development was performed in the same manner in such a developing device, a high-density, wide-area solid black image could be always obtained with a uniform density in the axial direction.

[0030]

As described above, the developing device of the present invention has the developer replenishing port at the central portion in the axial direction of the developer carrying member, and agitates the replenished developer to remove the developer carrying member. Since it is equipped with a rotary stirring member for equalizing the distribution of the developer amount in the axial direction, it is possible to continuously develop a high density, wide area solid black image without increasing the size of the developing device. It is possible to prevent the unevenness of the layer thickness distribution of the developer layer in the axial direction of the developer carrier, and to stably obtain a good image having a uniform density. Further, since the developer replenishing port is connected to the cylindrical developer carrying path, the developer carrying path is extended to dispose the developer storage box at a position away from the developer carrying device. It can be placed in a small space around the body.

[Brief description of drawings]

FIG. 1 is a schematic perspective view and a schematic sectional view showing a developing device which is a first embodiment of the present invention.

2A and 2B are a perspective view, a front view, and a side view of a rotary stirring member used in the developing device of the above embodiment.

FIG. 3 is a cross-sectional view showing a state in which a partition plate is attached to the developer supply port of the developing device of the above-described embodiment.

FIG. 4 is a diagram showing the density of an image developed by using the developing device of the above-described embodiment in comparison with the density of an image by a conventional developing device.

FIG. 5 is a diagram showing a relationship between a developer transfer distance and time in the developing device of the above embodiment.

FIG. 6 is a diagram showing a relationship between a developer transfer distance and time in a conventional developing device.

FIG. 7 is a schematic sectional view showing a developing device which is a second embodiment of the present invention.

FIG. 8 is a perspective view and a schematic sectional view showing an example of a conventional developing device.

FIG. 9 is a perspective view and a schematic cross-sectional view showing another conventional developing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developer carrying member 2 Electrostatic latent image holding member 3 Developer regulating member 4 Rotating stirring member 5 Electrostatic latent image 6 Developer accommodating chamber 7 Housing 8 Developer replenishing port 9 Developer conveying path 10 Developer conveying means 11 Development Agent storage box 12 Projection 13 Partition plate 14 Developer supply paddle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Yamamoto 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Zero Tux Co., Ltd.

Claims (2)

[Claims] 1. A developer carrying member, which is provided so as to face an electrostatic latent image holding member and conveys a developer by adhering the developer to the surface thereof, and a developer amount on the developer carrying member is regulated to reduce the amount of the developer. A developer regulating member forming a layer is provided in the housing, and the developer on the surface of the developer carrier is kept in the developing area where the developer carrier and the electrostatic latent image carrier closely face each other. In a developing device for visualizing an electrostatic latent image on an electrostatic latent image carrier by adhering it to the electrostatic latent image, the developing device is arranged substantially parallel to the axial direction of the developer carrier, and rotates to transport the developer and also inside the housing. A rotary stirring member that stirs the developer stored in the developer carrier to equalize the distribution of the developer in the axial direction of the developer carrier, and in the housing in a substantially central portion in the axial direction of the developer carrier. , A developer replenishment port connected to the cylindrical developer transport path Developing apparatus is characterized in that it has. 2. The developing device according to claim 1, wherein the rotary stirring member is a tubular member having a plurality of openings on a peripheral surface thereof and rotates about an axis of the tubular member. ..