JPH0643744A - One-component developing device - Google Patents

Abstract

PURPOSE:To miniaturize a one-component developing device by which an image including a solid black part having a wide area is reproduced with uniform density and the increase of torque is prevented and to make production cost low. CONSTITUTION:A supply member 4 having plural apertures 4b on the peripheral surface of a cylindrical member 4a is rotatably provided close to a developer carrier 1. When the member 4 is rotated, developer is supplied from the member 4 to a developer carrier 1 by the centrifugal force and electrostatic force. By setting the difference of circumferential speed and electric field between the supply member 4 and the developer carrier 1 to a specified condition, the thin layer having uniform and sufficient thickness is formed on the developer carrier 1, thereby stably reproducing the image including the solid black part having the wide area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component 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, as a developing device for visualizing an electrostatic latent image using a one-component developer, there is provided a developer carrying member provided so as to face an electrostatic latent image holding member. 2. Description of the Related Art There is known one provided with a developer regulating member and a developer supply section around the body.

In such a one-component developing device, the developer stored in the hopper or the like is supplied from the developer supply section to the developer carrier. The developer carrying member is designed so that the developer can be conveyed by adhering the developer to the surface thereof. Further, the developer regulating member is provided so as to come into contact with the developer carrier at a predetermined pressure, and the developer adhering to the surface of the developer carrier is regulated by this to form a uniform thin layer. The desired charge is imparted. After that, the developer is sent to a position facing the electrostatic latent image holder, and the developer flies to the electrostatic latent image holder due to the oscillating electric field generated between the electrostatic latent image holder and the developer carrier. Develop the latent image.

In the case of performing such development, when reproducing an original having a low density or a character original, a large amount of developer is not required at one time, so uniform development is performed and a good visible image is obtained. However, when trying to reproduce an image that has a very high density and a solid black area in a large area, the amount of developer consumed becomes large at one time, so the supply of developer becomes insufficient, and an image of uniform density appears. You may not get it.

In order to solve such a problem, FIG.
The developing device as shown in FIG. In order to uniformly supply a large amount of developer to the developer carrying member 101, this developing device applies a uniformizing member 104 made of an elastic body that is rotated in pressure contact with the developer carrying member 101, and the developer 112 to the developer. It has developer transport members 110 and 111 that are transported so as to circulate in the axial direction of the carrier 101 and always keep the amount of the developer 106 in the developer storage chamber 105 constant. In this figure, reference numeral 102 is an electrostatic latent image holder, reference numeral 103 is a developer regulating member, reference numeral 107 is an AC power source, and reference numerals 108 and 1 are provided.
Reference numeral 09 is a DC power supply.

In such a developing device, the developer is strongly rubbed against the developer carrying member 101 by the uniformizing member 104 to give an appropriate electric charge and the DC power source 109.
A large amount of developer is uniformly supplied by the bias voltage applied between the developer carrier 101 and the developer carrier 101.

[0007]

However, in the one-component developing device having the above-mentioned structure, the uniformizing member 104 is used.
Is pressed against the developer carrying member 101 by a contact pressure such that the contact depth is about 1 mm.
It increases or fluctuates the torque of (not shown) and causes unevenness on the copy. In addition, since stress is applied to the developer, the characteristics of the developer are changed over a long period of time, resulting in a decrease in the charge amount of the developer, a consequent deterioration in image quality, and contamination of the apparatus due to scattering of the developer. . Further, the developer conveying members 110 and 111 are required, which causes a problem that the device becomes complicated and large and the manufacturing cost becomes high.

On the other hand, a means for uniformly supplying a large amount of developer without contacting the member for supplying the developer to the developer carrier with the developer carrier can be considered (see Japanese Patent Application No. 2-218594). However, if the member that supplies the developer is not in contact, the supply efficiency of the developer is poor, so the number of rotations of the supply member must be significantly increased in order to stably supply an image including a solid black portion of a large area. It is necessary to raise the voltage or the voltage between the supply member and the carrier.

However, if the rotation speed of the supply member is significantly increased, the developer is stressed excessively, or the voltage between the supply member and the carrier becomes higher than an appropriate value, and the developing performance is deteriorated. Occurs. In addition, due to long-term development, the particles of the developer aggregate, the adhesive force increases, and the reverse polarity developer gathers in the vicinity of the supply member, resulting in a thin layer formed on the developer carrier. There is also a problem that the image becomes non-uniform and uneven density occurs in the image.

The present invention has been made in view of the above circumstances, and an image including a solid black portion of a large area can be obtained by defining the developer transport condition between the developer carrier and the supply member. An object of the present invention is to provide a one-component developing device capable of reproducing uniform density and preventing an increase in torque, which is small in size and low in manufacturing cost.

[0011]

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, and the developing device. The developer holding member, which regulates the amount of the developer on the developer carrier to form a thin layer of the developer, and the supply member, which is arranged substantially parallel to the developer carrier and rotates around the axis, In a developing area where the carrier and the electrostatic latent image holder are closely opposed to each other, the developer on the surface of the developer carrier is attached to the electrostatic latent image on the electrostatic latent image carrier to visualize the developer. In the component developing device, the peripheral speed of the supply member is V _T , the peripheral speed of the developer carrier is V _D , and the distance between the supply member and the developer carrier is d (m
m), the bias voltage between the supply member and the developer carrier is E
(V): | E / d | (V / mm) ≧ −200 (V / mm) V _T / V _D
It is characterized in that the development is performed under the condition of +1000 (V / mm).

The peripheral speed ratio between the supply member and the developer carrying member is preferably 0 <V _T / V _D <5.

[0013]

In the one-component developing device having the above-described structure, the developer is supplied to the developer carrier by the electric field between the developer carrier and the supply member, and the supply member is rotated at the same time. The developer is released from the supply member by the centrifugal force due to the rotation, and a sufficient amount of the developer is supplied by sprinkling it on the surface of the developer carrier.

However, in the case of always trying to stably reproduce an image including a solid black portion having a large area, a limit value occurs due to the structure of the developing machine and the stress applied to the developer. The ratio of the developer supplied to the body and the developer released from the supply member due to the centrifugal force is determined by the above formula, so that an image containing a wide solid black portion can be stabilized without any problem as a developing machine. Can be reproduced. In this case, the amount of developer supplied by the electric field is determined by the distance between the carrier and the supply member and the voltage applied between them, and when supplied by centrifugal force, it is determined by the peripheral speed ratio between the two. To be done.

As described above, the supply of the developer to the developer carrying member is determined by the condition between the developer carrying member and the supplying member, so that the image device can be downsized and the cost can be reduced.

[0016]

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

FIG. 1 is a schematic cross-sectional view showing the structure of a one-component developing apparatus which is an embodiment of the present invention, and is a view in a cross section in a direction perpendicular to the width direction of an image to be developed. This one-component developing device controls a developer carrier 1 having a cylindrical shape that rotates in opposition to an electrostatic latent image carrier 2, a developer adhesion amount on the developer carrier 1, and a thin developer. It has a developer regulating member 3 that forms a layer, and a supply member 4 that conveys the developer in the axial direction of the developer carrier while stirring and supplies the developer to the developer carrier 1.

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. The developer carrying member 1 has a diameter of about 5 to 40 mm and preferably rotates at 100 to 300 times / min. In this embodiment, the diameter is 20 mm,
It is designed to rotate at 200 times / minute. The developer carrying member 1 is formed by cutting a round bar or pipe made of aluminum or stainless steel, then providing a semiconductive layer of phenol resin or the like on the circumferential surface, and performing mechanical polishing such as emery polishing to obtain a surface roughness Ra. = About 0.1 to 1.0 μm. Volume resistance of phenol resin in the thickness direction is 10 ⁵
-10 ¹² Ωm.

The developer carrying member 1 is formed by cutting a round bar or pipe made of aluminum or stainless steel, and then subjecting the circumferential surface to mechanical processing such as sand blasting, liquid honing or emery polishing, or chemical corrosion. As a result, an unevenness of Ra = about 0.1 to 1.0 μm may be formed.

A DC superimposing AC voltage is applied to the developer carrying member 1 from the developing bias power sources 8 and 9, and the developer carrying member 1 is formed in the developing area A which is a position close to the electrostatic latent image holding member 2. Due to the electric field, the developer having a charge causes the electrostatic latent image 5
It is designed to adhere to. The power source 8 is a DC superimposing AC power source, and the power source 9 is a DC power source.

The developer regulating member 3 has a thickness of 0.03 to 0.
The leaf spring 3a made of stainless steel of about 3 mm is vulcanized and bonded with Si rubber or EPDM rubber, and is in contact with the developer carrying member 1 at a contact pressure of about 20 to 200 gf / cm. As a result, the developer is formed into a thin layer of about 5 to 30 μm, and an electric charge of about 2 to 20 μC / g is applied.

As shown in FIG. 1, the supply member 4 is supported in the vicinity of the developer carrying member 1 in a developer stirring chamber 6 provided at a position facing the developer carrying member 1 to support the developer carrying member 1. It rotates in the same direction as body 1. This supply member 4 is shown in FIG.
As shown in (b), it is desirable to use a cylindrical member 4a of aluminum or stainless steel having a diameter of about 6 mm to 30 mm with a plurality of openings 4b formed by cutting,
In this embodiment, an aluminum cylindrical member 4a having an outer diameter of 17 mm and an inner diameter of 10 mm is used. The opening 4b is a cylindrical member 4a.
Is cut substantially in the shape of an ellipse on the peripheral surface of the cylindrical member 4a and is linearly arranged along the axial direction of the cylindrical member 4a, and the axial length L1 of the open hole portion and the distance L2 between the open holes are It is provided so as to be almost equal.

Further, the row of the openings 4b has 90 rows in the circumferential direction.
Four rows are provided at positions distributed by degrees, and the positions of the openings are arranged so as to be offset from the positions of the openings in the adjacent rows by 1/2 pitch.

It is necessary that the ratio (opening ratio) of the openings 4b to the total circumferential area is 20 to 70%, and 30 to 60%.
It is desirable that it is a degree. In this embodiment, the open area ratio is about 50%.

A bias voltage is applied from a developer supplying bias power source 9 between the supply member 4 and the developer carrying member 1, and a sufficient developer is supplied from the supply member 4 to the developer carrying member 1. It has become so.

FIG. 3 is a diagram showing a one-component developing device 10 of this embodiment and a developer storage box 11 provided outside, and the developer in the developer storage box 11 is one component through the developer transport path 12. The developing device 10 supplies the toner to the inside 4c of the cylindrical member 4a of the supply member 4 shown in FIG.

As the developer used in the one-component developing device 10 as described above, a non-magnetic one-component developer, which is a pigment such as carbon or a metal-containing azo dye in various thermoplastic resins such as styrene resin and acrylic resin, is used. A polarity control agent such as the above is dispersed and pulverized and classified to a size of 5 to 20 μm, and a charge control agent externally added can be used. As the charge control agent, fine particles of 0.1 μm or less such as silica, alumina, and titanium that have been hydrophobized are used, and hydrophobic silica is most preferable.

Next, the operation of the above-described one-component developing device will be described.

When the developer is introduced from the developer storage box 11 outside the one-component developing device 10 into the inside 4c of the supply member 4 through the developer transport path 12, the supply member 4 rotates to gradually supply the developer. The developer is conveyed in the axial direction of the member 4, and the developer is substantially evenly distributed in the width direction in which the image is formed.
At the same time, by rotation of the supply member 4, the developer is discharged into the developer stirring chamber 6 through a plurality of openings 4b provided in the peripheral surface.

The supply member 4 and the developer carrying member 1 are in the range of 0.2 to
The peripheral speed of the supply member 4 is set to be about 1 to 5 times the peripheral speed of the developer carrying member 1 so as to face each other at an interval of about 3 mm, and the developer released from the inside by the rotation of the supply member 4 is The developer flies toward the surface of the developer carrier 1, and a large amount of the developer adheres to the surface of the developer carrier 1. Further, a bias voltage is applied between the supply member 4 and the developer carrying member 1,
Helps evenly distribute large amounts of developer.

In FIG. 4, the horizontal axis represents the rotational speed R _T of the supply member 4,
The vertical axis represents the amount of developer that is transported immediately before the transport amount regulating member 3. Although the amount of the developer increases as the rotation speed R _T increases, the point where the developer supply failure occurs is not uniquely determined by the amount of the developer, but depends on the voltage between the developer carrier and the supply member. The difference is that the developer supply failure actually occurs.

Here, the voltage applied between the developer carrier and the supply member is E. In this embodiment, the distance between the developer carrying member 1 and the supply member 4 is 1 mm. Specifically, as is clear from the graph, the supply member is set to 800 rpm or more when E = 200V and 60 rpm when E = 400V.
In the case of 0 rpm or more and E = 600 V, a supply failure occurs unless rotating at 400 rpm or more, but E = 8.
In the case of 00V, sufficient layer formation without developer supply shortage is possible even when the amount immediately before the transport amount regulating member is 1 mg / cm ^{2 at} about 200 rpm.

Further, the amount of the developer transported immediately before the transport amount regulating member differs depending on the voltage E. When the voltage E is high, the supply of the developer from the supply member 4 to the developer carrier 1 is dominated by the movement due to the electric charge. Since the developer supplied by the electric charge adheres to the developer carrier 1 with a relatively strong force due to the electrostatic force, as shown in FIG.
The developer D _S supplied from the supply member 4 to the developer carrier 1
Many parts of the electrostatic latent image holder 2 pass through the regulating member 3.
The developer D _D that is supplied to the toner and contributes to the development increases. On the other hand, when the voltage E is low, the supply of the developer from the supply member 4 to the developer carrying member 1 is dominated by the movement due to the centrifugal force. When the supply rate by the centrifugal force is high, the adhesive force between the developer and the developer carrying member 1 is weak, so that the developer D that cannot be passed through the regulating member 3 and is returned as shown in FIG. Developer D _D that increases the amount of _R and contributes to development
Is less.

As described above, it is the developer supplied by the electric field that easily passes through the regulating member 3. However, in order to perform a sufficiently stable supply in consideration of the occurrence of leak and the reduction of stress applied to the developer, it is necessary to supply by both the electric field and the centrifugal force.

Here, the peripheral speed of the supply member 4 is V _T , the peripheral speed of the developer carrying member 1 is V _D , and the distance between the supply member 4 and the developer carrying member is d (mm). The horizontal axis represents the speed ratio V _T / V _D , the vertical axis represents the electric field E / d (V / mm), and the developer supply failure occurs (indicated by a black circle) and the developer supply failure does not occur. Plotting (indicated by white circles) results in the graph shown in FIG.

The region in which stable supply is performed, which is indicated by a white circle in the graph of FIG. 6, is expressed by the formula | E / d | (V / mm) ≧ −200 (V / mm) V _T / V _D
It is represented by +1000 (V / mm).

Therefore, under the condition that this expression is satisfied, the stable supply of the developer is always performed. In addition, in consideration of downsizing and stress reduction of toner, 0 <V _T /
It is preferable that V _D <5.

In order to confirm the time-dependent stability of the developing process as described above, a long-term development test was conducted in which continuous development was performed 50,000 times with the one-component developing apparatus of the above-mentioned embodiment. No image defects such as defects were observed and good results were obtained.

The constitution of the supply member is not limited to that shown in FIG. 2, and as shown in FIG. 7, a large number of wire rods made of a material having the same charge polarity as the developer are provided radially. It is also possible to use a brush-shaped supply member 13. That is, as the supply member, a structure or member capable of supplying to the developer carrier by the electric field between the developer carrier and the supply member and the centrifugal force due to the rotation of the supply member may be appropriately selected.

[0040]

As described above, in the one-component developing apparatus of the present invention, the distance between the supply member, which is arranged in parallel with the developer carrying member and rotates, the number of rotations, and the bias condition to be applied are set. By setting the specific conditions, it is possible to supply a sufficient amount of developer without stressing the developer and without difficulty in the structure of the developing machine, and to reduce deterioration of the developer. As a result, it is possible to form a stable layer which is always uniformly charged, and to obtain a sufficient density and an image of good quality even if an image including a solid black portion is continuously developed. it can.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of a one-component developing device that is an embodiment of the present invention.

FIG. 2 is a perspective view showing a supply member used in the one-component developing device shown in FIG.

FIG. 3 is an external view showing a state in which a developer storage box is connected to the component developing device shown in FIG.

FIG. 4 is a graph showing the relationship between the number of rotations of the supply member, the conveyance amount immediately before the conveyance amount regulation member, and the supply failure occurrence region.

FIG. 5 is a schematic diagram showing the difference in the flow of the developer depending on the level of the voltage E between the developer carrier and the supply member.

FIG. 6 is a graph showing a relationship between a speed ratio V _T / V _D and an electric field E / d and a developer supply failure occurrence state.

FIG. 7 is a schematic sectional view showing the configuration of another embodiment of the one-component developing apparatus of the present invention.

FIG. 8 is a schematic cross-sectional view showing the configuration of a conventional one-component developing device.

[Explanation of symbols]

1 developer carrier, 2 electrostatic latent image holder, 3 developer regulating member, 3a leaf spring, 4 supply member, 4a cylindrical member, 4b opening, 4c cylindrical member inside, 5 electrostatic latent image,
6 developer stirring chamber, 7 housing, 8 developing bias power source, 9 developer supplying bias power source, 10 one-component developing device, 11 developer storage box, 12 developer transport path,
13 supply member, 101 developer carrying member, 102 electrostatic latent image holding member, 103 developer regulating member, 104 uniformizing member, 105 developer accommodating chamber, 106 developer, 107
AC power supply, 108 DC power supply, 110, 111 developer transport member, 112 developer

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

Claims (2)

[Claims] 1. A developer carrier which is provided so as to face an electrostatic latent image carrier and which adheres and conveys a developer on its surface, and a developer amount which regulates the amount of the developer on the developer carrier to make the developer thin. A developer regulating member that forms a layer and a supply member that is arranged substantially parallel to the developer carrying member and rotates about an axis line are provided, and the developer carrying member and the electrostatic latent image holding member are closely opposed to each other. In the developing area, the developer on the surface of the developer carrier is attached to the electrostatic latent image on the electrostatic latent image carrier to visualize the latent image, and the peripheral speed of the supply member is set to V _T , When the peripheral speed of the developer carrier is V _D , the distance between the supply member and the developer carrier is d (mm), and the bias voltage between the supply member and the developer carrier is E (V), | E / d | (V / mm) ≧ −200 (V / mm) V _T / V _D
A one-component developing device, which develops under conditions satisfying +1000 (V / mm). 2. The one-component developing device according to claim 1, wherein a peripheral speed ratio between the supply member and the developer carrying member is 0 <V _T / V _D <5.