JPH0511594A - One-component developing device - Google Patents

Abstract

PURPOSE:To reduce the stain of a formed image and soiling inside the machine of an image forming device by reducing toner grains scattering outside a developing region, on a one component developing device soaring up a developer on the surface of a developer carrier and visualizing an electrostatic latent image on an electrostatic latent image holder in an oscillating electric field generated by imparting an AC bias voltage between the developer carrier and the electrostatic latent image holder. CONSTITUTION:As the developer carrier, two developing rolls 2 and 3 get near to the electrostatic latent image holder 1, and are arranged so as to be near each other and in parallel, and the interval of the electrostatic latent image holder 1 and two developing rolls 2 and 3 and the interval and rotational directions of two developing rolls, are set, so that the flowing of the air into a region 13 surrounded by the electrostatic latent image holder 1 and two developing rolls 2 and 3 are generated at respective positions A and B where two developing rolls 2 and 3 face the electrostatic latent image holder 1.

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 to make it visible. The present invention relates to a one-component developing device that visualizes an electrostatic latent image by flying a developer in an oscillating electric field generated between a body and a developer carrying body.

[0002]

2. Description of the Related Art Conventionally, a so-called non-contact type developing device using a one-component developer has been used as a developing device for obtaining a sharp image, which is used in an image forming apparatus such as an electrophotographic copying machine or an electrostatic printer. It is disclosed in Japanese Patent Laid-Open No. 55-18658. This is for developing by flying the developer in an oscillating electric field without contacting the developer adhering to the surface of the developer carrier and the electrostatic latent image carrier, and for example, a configuration as shown in FIG. Has become.

The electrostatic latent image holder 21 is capable of forming an electrostatic latent image on the surface due to the difference in charging potential by irradiation of image light, and is rotated at a predetermined speed. The developer carrying member 22 is provided so as to closely face and oppose the electrostatic latent image holding member 21, and toner can be attached to the surface of the developer carrying member 22 and conveyed. This developer carrier 2
A DC weight AC voltage can be applied to the AC high voltage power supply 24 and the DC power supply 25, and an alternating electric field is formed at a position close to the electrostatic latent image holder 21, that is, in the developing area 27. Around the developer carrier 22, a developer regulating member 23 that regulates the amount of toner supplied from the hopper 26 to the developer carrier 22 and forms a thin layer of toner is provided. It is projected and supported so as to be close to the surface of the carrier.

In such a developing device, a thin layer of toner formed on the surface of the developer carrier is conveyed to the developing area 27 by the rotation of the developer carrier 22, and this developing area 27 is used.
The toner flies in the alternating electric field generated in the above, adheres to the electrostatic latent image on the electrostatic latent image holding body 21, and is developed.

[0005]

However, the conventional developing device as described above has the following problems. In the developing area, each toner particle flying from the surface of the developer carrier does not always draw the same trajectory due to the difference in the amount of charge and the mass of the toner particle, and the one electrostatically adsorbed to the electrostatic latent image carrier. , Some return to the surface of the developer carrier. There are also toner particles that can no longer follow the alternating electric field during flight and those that are out of orbit due to collision of toner particles. Floating toner particles that are not adsorbed on either the electrostatic latent image holder or the developer carrying member are entrained in the air flow generated around the rotating electrostatic latent image holding member and the developer carrying member. In some cases, a so-called toner cloud is generated that is scattered outside the developing area.

The toner particles scattered outside the developing area cause the background stain of the formed image, and
Therefore, the so-called non-contact type one-component developing device in the related art is a two-component developing device that forms a spike of developer and contacts the electrostatic latent image for development. On the other hand, there is an advantage that a sharp image can be obtained, but as described above, there is a problem that a large amount of toner is scattered outside the development area, and the background of the formed image and the stain of the device are likely to occur. There is. The present invention has been made in view of the above problems, and it is possible to reduce toner particles scattered outside the developing area, and reduce the background stain of the formed image and the stain inside the image forming apparatus. An object is to provide a one-component developing device.

[0007]

In order to solve the above-mentioned problems, the present invention is arranged to face an electrostatic latent image carrier,
It is equipped with a developer carrier that adheres the developer to the surface and conveys it.
In the oscillating electric field generated by applying an AC bias voltage between the developer carrying member and the electrostatic latent image holding member, the developer on the surface of the developer carrying member is caused to fly to generate an electrostatic latent image. In a one-component developing device for visualizing an electrostatic latent image on a holding body, the developer carrying body is two developing rolls arranged in close proximity to each other, and these two developing rolls are the above-mentioned developing rolls. The rotation direction is set so that the surface of each developing roller moves in a direction in which the other developing roller moves in a position facing the electrostatic latent image holding member. It is assumed that the distance from the surface of the roll and the distance between the surfaces of the two developing rolls are set so as to generate an air flow in the moving direction of the surface of the developing roll at the close position.

Further, in the above-mentioned one-component developing device, in a developing region where the developing roll and the electrostatic latent image holding member face each other, on an upstream side and a downstream side in a rotating direction of the electrostatic latent image holding member, It is desirable to have a plate-like member provided so that its front end is close to the electrostatic latent image carrier, and a diffusion preventing member for preventing the toner cloud from diffusing from the developing area.

The space between the surfaces of the two developing rolls causes an air flow due to the rotation of the developing rolls in a portion where they are close to each other, and is surrounded by the two developing rolls and the electrostatic latent image holding member. The interval is set so that the air in the area can be discharged to the toner reservoir side. Therefore, the toner is set so as not to stay in the area surrounded by the two developing rolls and the electrostatic latent image carrier,
It is desirable to set the amount of discharged air to be large. The distance between the developing roll and the electrostatic latent image holding member is defined as an interval at which toner flies due to the alternating electric field formed in this portion so that the toner can be efficiently developed. It is desirable that the interval is such that an air flow in the inner direction of the region surrounded by the developing roll and the electrostatic latent image carrier is likely to occur at the portion facing the electrostatic latent image carrier. The diffusion prevention member is made of a conductive material, and a bias voltage having a polarity opposite to that of the toner can be applied. In this case, it is desirable to cover the plate-shaped diffusion prevention member with a thin insulating layer.

[0010]

In the one-component developing device having the above-described structure, two developing rolls arranged in parallel and close to each other face the electrostatic latent image holding member, each of which is shown in FIG. The rotation is set so that the surfaces of the developing rolls 2 and 3 move in a certain direction in the other developing roll at the position facing the electrostatic latent image holding member 1 as indicated by arrows G and H. ,
3 at the position where the electrostatic latent image holding member 1 faces the developing roller 2,
An air flow due to the movement of the surface of 3 is generated in the directions shown by arrows I and J in FIG. Therefore, the developing rolls 2 and 3 fly at a position where the electrostatic latent image holding member 1 faces each other, that is, at a developing region,
Most of the toner particles floating without being adsorbed by the electrostatic latent image carrier 1 and the developing rolls 2, 3 are surrounded by the two developing rolls 2, 3 and the electrostatic latent image carrier 1. It flows into the area 13. Further, even at a position where the two developing rolls 2 and 3 face each other, an air flow is generated in the direction of arrow L in FIG.
The air in the area 13 surrounded by the developing rollers 2 and 3 of the book and the electrostatic latent image holder 1 is discharged to the side opposite to the side where the developing rollers 2 and 3 face the electrostatic latent image holder 1. . This portion serves as a toner reservoir that stores the toner supplied to the developing rolls 2 and 3, and extends from the developing region to a region 13 surrounded by the two developing rolls 2 and 3 and the electrostatic latent image carrier 1. The toner particles that have flowed in are discharged to this toner reservoir and hardly diffuse to the outside. Therefore, the toner cloud diffused from the developing area to the outside of the developing device is reduced.

In the developing device having the diffusion preventing members on the upstream side and the downstream side of the developing area in the rotation direction of the electrostatic latent image carrier,
The diffusion of the air flow generated near the developing area is blocked, and the diffusion of toner particles floating near the developing area without flowing into the area surrounded by the two developing rolls and the electrostatic latent image carrier is prevented. It Further, by applying a bias voltage to the plate-shaped diffusion preventing member, the charged toner particles are adsorbed and the diffusion preventing effect of the toner particles is improved. At this time, since the diffusion preventing member is covered with a thin insulating layer, discharge is prevented from occurring at a position close to the electrostatic latent image holder when a bias voltage is applied, and the electrostatic latent image is generated by the discharge. Defects in the image on the image carrier are prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a one-component developing device which is an embodiment of the present invention. In this figure, the electrostatic latent image carrier 1 is uniformly charged, and then an electrostatic latent image is formed by the difference in charging potential by the irradiation of image light. The developing device 100 is provided so as to face the electrostatic latent image holder 1, and two parallel developing rolls 2, 3 that are close to each other and are also close to the electrostatic latent image holder 1 are provided.
And pressed against the two developing rolls 2 and 3,
The two developer regulating members 4 and 5 that regulate the amount of toner on the developing roll to form a thin layer of toner and the two developing rolls 2 and 3 rotate in proximity to each other, and the toner is removed from the developing roll. Two toner supply rolls 6 and 7 for supplying the surface,
It has diffusion preventing members 8 and 9 for preventing the toner cloud from diffusing from the developing areas A and B.

The developing rolls 2 and 3 are capable of adsorbing and conveying toner on their surfaces, and their circumferential surfaces are made of phenol resin or alumite, and are rotatively driven. The direction of these rotations is such that the surface of the developing roll moves inward (at the side where the two developing rolls face each other) at a position facing the electrostatic latent image carrier 1 as indicated by arrows C and D shown in FIG. Is set to. Further, the gap between the electrostatic latent image holder 1 and the developing rolls 2 and 3 is 100 to
500 μm, the gap between two developing rolls is 0.2-5 m
It is set in the range of m.

The developer regulating members 4 and 5 are the developing rolls 2 and
3, a thin layer of developer is formed on the toner, and the toner is rubbed against the toner to impart an electric charge to the toner by frictional charging.
PDM rubber or silicone rubber was adhered and pressed against the surface of the developing roll at a contact pressure of 50 to 200 g / cm. The developer regulating members 4 and 5 have a thickness of 5 to 5 when a styrene acrylic or polyester non-magnetic negatively charged toner having an average particle diameter of 5 to 20 μm is used.
A 40 .mu.m toner layer is formed on each of the developing rolls 2 and 3 so that the toner charge amount is 2 to 35 .mu.C / g. The soft elastic body pressed against the developing rolls 2 and 3 may be made of EPDM rubber or silicon rubber, and other materials depending on the toner material.

The toner supply rolls 6 and 7 are made of hollow cylindrical aluminum tubes and are provided with a plurality of holes on their peripheral surfaces. These toner supply rolls 6 and 7 are combined with a developing roll and 0.2
It is supported with a gap of about 3 mm, and is indicated by arrows E and F in the figure.
As shown in FIG. 3, the developing rolls 2 and 3 are rotated in the same direction as the developing rolls 2 and 3 which are close to each other, at a peripheral speed of about 1 to 3 times the developing roll. A bias voltage having the same polarity as that of the toner used is applied to the two toner supply rolls 6 and 7, and the potential difference with the developing rolls 2 and 3 is 1500 V or less, so that discharge under the bias voltage does not occur. It is set to the range.

The diffusion preventing members 8 and 9 are made of a conductive plate member attached to a frame supporting a developing roll of the developing device, a toner supplying roll and the like, and develop in the rotating direction of the electrostatic latent image carrier 1. The tips are provided on the upstream side and the downstream side of the regions A and B so as to project from the electrostatic latent image holding body 1 at a distance of about 0.5 to 2 mm. The surfaces of the diffusion preventing members 8 and 9 are insulation-coated by attaching or coating a tape made of fluororesin or the like, and a bias voltage having a polarity opposite to that of the toner used is applied. At this time, the potential difference between the diffusion preventing member and the electrostatic latent image holding member is 500 to 100.
It is about 0 volt. A toner replenishing port 14 communicating with the toner reservoir 12 from the outside is provided on the side surface of the developing device 100, and toner is replenished by a toner replenishing auger 11 from a toner storage box (not shown) provided outside the developing device 100. You can do it.

In such a one-component developing device, the toner supply rolls 6 and 7 are rotated and a bias voltage is applied to the two developer rolls 2 and 3 from the toner reservoir 12.
Toner is supplied to each. The toner supplied to the surfaces of the developing rolls 2 and 3 is conveyed to the portions where the developer regulating members 4 and 5 are pressed. The developer regulating members 4 and 5 regulate the amount of toner on the developing rolls 2 and 3 to reduce the amount of toner, and at the same time, rub it to give an electric charge. The charged toner on the developing rolls 2 and 3 is conveyed to the developing areas A and B where the electrostatic latent image holding member 1 and the developing rolls 2 and 3 closely face each other, and the electrostatic latent image holding member 1 and Due to the alternating electric field generated by the DC weight AC voltage applied between the developing rolls 2 and 3, the surface of the developing rolls 2 and 3 is peeled off, and the electrostatic latent image holding body 1 flies toward the electrostatic latent image holding member 1 for development.

The toner that has not been adsorbed on the electrostatic latent image on the electrostatic latent image holder 1 is reattached to the developing rolls 2 and 3 or moves along the air flow near the developing areas A and B. . An airflow is generated in the moving direction of the peripheral surfaces of the developing rolls 2 and 3 in the vicinity of the developing regions A and B as the developing rolls 2 and 3 rotate. An air flow is formed in the area 13 surrounded by the developing rollers 2 and 3. Therefore, most of the toner that has not been electrostatically attracted to the electrostatic latent image is transferred along the air flow to the electrostatic latent image holders 1 and 2.
The area 13 surrounded by the book developing rolls 2 and 3 is sucked.

On the other hand, in a portion where the two developing rolls 2 and 3 closely face each other, the toner is collected from a region 13 surrounded by the electrostatic latent image carrier 1 and the two developing rolls 2 and 3. The air flow is generated toward the toner 12, and the toner sucked into the area 13 surrounded by the electrostatic latent image holder 1 and the two developing rollers 2 and 3 is discharged to the toner reservoir. Therefore, the developing device 100
The amount of toner dissipated to the outside of the printer is greatly reduced.

Incidentally, the electrostatic latent image carrier 1 and the developing roll 2,
The gap between the electrostatic latent image holding members 1 and 2 is set so that the air flow from the developing areas A and B to the toner reservoir 12 is efficiently generated.
A large amount of toner does not stay in the area 13 surrounded by the developing rollers 2 and 3 of the book. Also, the toner reservoir 1
The air flow guided to 2 is discharged to the toner storage box through the toner supply port 14. In the toner supply port 14, toner is conveyed by the toner supply auger 11, but the toner is not filled in the entire cross section of the toner supply port 14, and sufficient ventilation is ensured. Also, the toner reservoir 1
The air flow guided to 2 may be exhausted from a toner reservoir provided with a discharge port communicating with the outside of the developing device through a filter.

In the developing areas A and B, the toner that is not attracted to the electrostatic latent image and is not attracted to the inside of the developing device is
Although it floats in the vicinity of the development areas A and B, the diffusion prevention members 8 and 9 prevent diffusion in a wide area.
By applying a bias voltage having a polarity opposite to that of the toner to the diffusion preventing members 8 and 9, the floating toner can be adsorbed and the diffusion can be prevented more efficiently.
At this time, the insulating layer provided on the surfaces of the diffusion preventing members 8 and 9 prevents discharge from occurring under a bias voltage between the diffusion preventing members 8 and 9 and the electrostatic latent image holding member 1.

[0022]

As described above, the one-component developing device of the present invention has two developing rolls arranged in close proximity to each other, and these developing rolls are electrostatic latent image holding members. Since the surface of each developing roll rotates so that the other developing roll moves in a certain direction at a position facing with, the developing area passes through the area surrounded by the electrostatic latent image carrier and the two developing rollers. An air flow reaching the toner reservoir is generated, and the amount of toner diffused outside the developing device can be reduced. Further, by providing the diffusion preventing members on the upstream side and the downstream side in the rotation direction of the electrostatic latent image holding member in the developing area, it is possible to more efficiently prevent the toner from diffusing to the outside of the developing device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a one-component developing device that is an embodiment of the present invention.

FIG. 2 is an explanatory view showing the operation of the present invention.

FIG. 3 is a schematic configuration diagram showing a conventional one-component developing device.

[Explanation of sign]

1 Electrostatic Latent Image Holder 2, 3 Developing Roll 4, 5 Developer Controlling Member 6, 7 Toner Supply Roll 8, 9 Diffusion Preventing Member 11 Toner Replenishing Auger 12 Toner Reservoir 13 2 Developing Roll and Electrostatic Latent Image Holding Area 14 surrounded by the body 14 Toner supply ports A, B Development area

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mikio Yamamoto             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             Tux Corporation Ebina Office

Claims (2)

[Claims] 1. An electrostatic latent image holding member is arranged to face the electrostatic latent image holding member,
It is equipped with a developer carrier that adheres the developer to the surface and conveys it.
In the oscillating electric field generated by applying an AC bias voltage between the developer carrying member and the electrostatic latent image holding member, the developer on the surface of the developer carrying member is caused to fly to generate an electrostatic latent image. In a one-component developing device for visualizing an electrostatic latent image on a holding body, the developer carrying bodies are arranged in parallel with each other.
These two developing rolls have rotation directions set such that the surface of each developing roll moves in a direction of the other developing roll at a position facing the electrostatic latent image holding member. The distance between the surface of the electrostatic latent image holding member and the surface of the developing roll, and the distance between the surfaces of the two developing rolls generate an air flow in the moving direction of the surface of the developing roll at the close position. A one-component developing device, which is set as follows. 2. A front end of the electrostatic latent image holding member is located on an upstream side and a downstream side of a developing region where the developing roll and the electrostatic latent image holding member face each other in a rotating direction of the electrostatic latent image holding member. The one-component developing device according to claim 1, further comprising a diffusion preventing member that is a plate-shaped member provided close to a body and that prevents the toner cloud from diffusing from the developing region.