JP2003215923A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply electrification to toner at high efficiency in a simple constitution without having the toner deteriorated even when a great quantity of the toner is consumed or when the device is operated in a high humidity environment in the developing device using a non magnetic one component toner. <P>SOLUTION: A toner contacting member 110 electrifying the toner 103 by being brought into contact with the toner 103 is installed in a position passed by toner reflux flow R formed by the rotation of a developing roll 106 imparting the non magnetic one component developer to a photoreceptor drum 112 and a toner feeding roll 107 installed adjacent to the developing roll 106. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device using a non-magnetic one-component developer and an image forming apparatus such as a copying machine, a printer and a facsimile.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic system, there are roughly two developing systems. One is a two-component developing method in which magnetic powder such as ferrite is used as a carrier and a two-component developer in which a carrier and toner are mixed is used to magnetically brush the two-component developer onto a developing roller to perform development. The other is a one-component developing method in which the toner is adhered onto the developing roller by using only the toner without using the carrier and the development is performed.

Even in the one-component developing method, there are two developing methods as a method of attaching the toner to the developing roller. 1
One is a magnetic one-component developing method in which magnetic powder is contained in toner and a toner layer is formed on the developing roller by the magnetic force of a magnet contained in the developing roller. The other is a non-magnetic one-component developing method in which a toner layer is formed on the developing roller by the attraction force of the charged toner.

In recent years, when the size of the apparatus is required to be small, a one-component developing system which can be downsized at low cost has been put to practical use in many products. In particular, in a device that outputs a color image, since the toner itself cannot contain magnetic powder because it impairs the color development of the toner, a non-magnetic one-component developing method that can form a toner layer without using magnetic force is often used. .

A typical example of a conventional developing device using a non-magnetic one-component developing system (hereinafter referred to as "non-magnetic one-component developing device") will be described below with reference to FIG.

In the non-magnetic one-component developing device shown in FIG.
Toner 801 having a negative charging characteristic is stored in the toner storage chamber 802. The toner 801 is sent to the developing chamber 805 through the passage opening 804 when the shutter 803 rotates in the arrow direction. At this time, the shutter 8
In No. 04, the toner amount in the developing chamber 805 is controlled so that the toner amount does not become excessive and the toner amount does not become insufficient.

A developing roller 806 and a toner supply roller 807 are disposed in the developing chamber 805 so as to come into contact with each other, and rotate in the directions of arrows X and Y, respectively.

The developing roller 806 has a volume resistivity of 10
A medium resistance elastic body such as urethane rubber or silicon rubber adjusted to about ⁷ Ω · cm to 10 ¹² Ω · cm is molded around a metal shaft and then ground into a cylindrical shape.

As the toner supply roller 807, a sponge roller in which a sponge such as urethane foam or silicon foam is formed into a cylindrical shape around a metal shaft is used. Each bubble on the surface of the sponge is adjusted to be larger than the particle diameter of the toner 801, and the surface of the sponge contains the toner 801 and is conveyed.

Developing roller 806 and toner supply roller 80
A toner layer thickness regulating blade 808 is arranged on the arrow X direction side from the contact position with the developing roller 806 so as to contact the developing roller 806 with a constant pressure.

Toner supply roller 807 in developing chamber 805
Conveys the nearby toner 801 on the sponge surface in the direction of arrow Y. The developing roller 806 and the toner supply roller 807 rotate in opposite directions at their contact portions. Therefore, the transported toner 801 is rubbed between the two, and is charged by the friction, and at the same time, the developing roller 80 is charged.
6 Attach to the surface by image force.

Toner 8 attached to the surface of the developing roller 806
No. 01 was evened by the toner layer thickness regulating blade 808, and at the same time, further charged by being rubbed with the contact surface of the toner layer thickness regulating blade 808 to form about 2 to 5 charged toner layers. After that, it is carried to the developing area.

Photosensitive drum 80 having a negative polarity
An electrostatic latent image is formed on the developing roller 9 and is in contact with the developing roller 806 in the developing area.

During development, the developing roller 806 holds the developing power source 8
By 10, a developing bias of about DC-300 V is applied. At this time, the electrostatic latent image on the photoconductor drum 809 is about −800 v at the non-printing portion potential and about −100 v at the printing portion potential.
The potential gradients of the non-printing portion / printing portion with respect to the developing roller 806 are in opposite directions.

Since the toner 801 attached to the surface of the developing roller 806 holds a negative charge,
In the developing area, an electric field that causes the toner 801 to face the photoconductor drum 809 is generated in the electrostatic latent image printing portion of the photoconductor drum 809. On the other hand, the toner 80
An electric field is generated that directs 1 toward the developing roller 806.

Therefore, the toner 801 is transferred to the developing roller 80 according to the electrostatic latent image corresponding to the image data in the developing area.
6 flies and adheres to the photoconductor drum 809. As a result, development is performed and a toner image is formed on the photoconductor drum 809.

As described above, in the non-magnetic one-component developing device, the toner 801 is mainly charged by the developing roller 806.
And toner supply roller 807 in the contact area between each roller and toner 801 due to frictional charging, and in the contact area between developing roller 806 and toner layer thickness regulating blade 808, toner layer thickness regulating blade 808.
And the toner 801 are rubbed against each other by frictional charging.

By the way, in recent years, there is an increasing demand for colorization of image forming apparatuses. Generally, in an electrophotographic color image forming apparatus, when fixing toner images of four colors on a transfer paper by heat and pressure, it is necessary to have excellent melting property and color mixing property in order to widen a color reproduction range. For this reason, sharp melt toner is used.

Such toner has a high affinity with the fixing roller and tends to be offset to the fixing roller. Further, since a toner resin such as polyester, which is often used as a color toner resin, contains wax as a release agent in the toner resin, it is difficult to disperse the wax and wax domains are easily generated.

In this case, since the wax adheres non-uniformly to the toner, an excessive amount of wax is required to obtain sufficient releasability. As a result, there is a problem that the charging property of the toner is obstructed, and conventionally, oil is applied to the fixing roller for the purpose of ensuring releasability.

However, in this case as well, there are problems such as an increase in the size of the device by the oil application device, the need for oil replenishment, and oil leakage. Therefore, due to demands for further downsizing of the apparatus and simplification of maintenance, oilless toner that is a color toner containing wax (hereinafter,
"Color toner for oilless fixing") is under development, and it has been partially commercialized.

However, according to the study by the present inventors, the above-mentioned oilless fixing color toner is an oil coating type color toner (hereinafter referred to as “oil coating type color toner”).
There is a tendency that the charging characteristics, especially the charging rise, are slightly inferior to

The study conducted by the present inventor is to measure the charge build-up characteristic of each toner using the oilless fixing color toners T1 and T2 and the conventional oil coating type color toner T. .

Here, each of T1 and T2 uses a polyester resin as a binder resin, a charge control agent of a metal salicylate compound and an azo pigment, and a plant wax as a release agent are uniformly dry mixed and melted by heat. Volume average particle diameter of 8 to 8 prepared by kneading and dispersing a pigment, charge control agent and release agent in a binder resin, cooling and pulverizing and classifying.
It is obtained by externally adding hydrophobic silica to 9-micron powder. The difference between T1 and T2 is the amount of the release agent.

The charge rising characteristics were measured by using a carrier for imparting triboelectrification to the toner and evaluating the degree of increase in the toner charge amount with respect to the stirring time when the toner and the carrier were mixed and stirred. Specifically, as a carrier, a Cu-Zn ferrite having a particle diameter of 80 μm coated with silicon was used, and 98 g of the carrier and 2 g of the toner were put into a polypropylene cylindrical container so that the toner concentration became 2 wt%. . Then, the cylindrical container was set in a ball mill, and the cylindrical container was rotated at a speed of 100 rpm to stir the toner and the carrier. At each rotation time, the agitated mixture of toner and carrier is sampled from the container, and the amount of charge per unit weight of toner is measured by a blow-off powder charging device (manufactured by Toshiba Chemical Co., Ltd.).

As a result of this examination, as shown in the graph of FIG. 9, in the oil-coating type color toner T, the charge rises at the initial stage and then becomes stable. However, on the other hand, the oilless fixing toners T1 and T2 rise slowly and it is necessary to stir for a certain period of time in order to achieve a constant level of charging.

Since the charge of such oilless toner is raised by stirring in the developing device for a certain period of time, it is necessary to raise the toner charge to some extent by the initial operation before developing.

[0028]

However, in the conventional developing device, when a document having a high image ratio such as a solid image or a photographic image is printed and a large amount of charged toner is consumed, When operating the device in a high-humidity environment, in the situation where the charging of the toner in the developing device is very low and the charging is suddenly started,
The charge of the toner is not sufficiently imparted, the toner cannot sufficiently fly to the photoconductor, and image defects such as fog and density decrease occur.

In order to improve the charging rise, the contact pressure between the developing roller 806 and the toner layer thickness regulating blade 808, or the developing roller 806 and the toner supplying roller 807.
Toner 8 is increased by increasing the contact pressure between
It is conceivable to increase the amount of triboelectric charge applied to No. 01. However, in this case, a new problem of toner deterioration occurs.

Here, the toner deterioration will be described. The toner 801 is usually a powder obtained by mixing a resin such as styrene or polyester with a colorant, a charge control agent, and a release agent, and pulverizing the powder to a size of about 5 to 20 μm in volume average particle size, and silica for improving fluidity. Etc. are added externally. When the toner 801 rubs against the member, if the frictional force is too strong, the external additive may be peeled from the resin surface or, on the contrary, deeply embedded,
It may happen that the initial liquidity is lost. For this reason, frictional charging becomes difficult to occur, and a phenomenon occurs in which the amount of charge is reduced. Such a phenomenon is usually called toner deterioration. Under the present circumstances, it is impossible to unnecessarily increase the contact pressure between each member and the toner 801 for the purpose of increasing the charge amount of the toner 801.

In particular, referring to oilless fixing color toners, these oilless fixing color toners tend to have a large amount of wax because development is focused on fixability. Therefore, as compared with the oil-coated color toner, there is a problem that it is more sensitive to the stress received in the developing device and is more likely to deteriorate.

In order to solve these problems, Japanese Patent Laid-Open No. 2001-4
In the Japanese Patent No. 2645, a toner circulation control means composed of a plate is provided above the toner supply roller to form a toner circulation region in which a small amount of toner circulates, and the toner is circulated many times in that region to increase the chance of frictional charging. ing. But,
When a document with a high image ratio such as a solid image or a photographic image is printed, the toner consumption is fast and the toner is consumed before it circulates many times in the toner circulation area, resulting in a low toner charge amount. However, there are problems that image defects such as fog and density decrease and toner scattering occur.

Further, in Japanese Unexamined Patent Publication No. 2001-194909, when a document having a high image ratio is printed, the rotation driving time before development is lengthened to sufficiently charge the toner. However, in this case, there is a problem in that, in continuous printing, the interval between the prints becomes long, and the productivity such as copying is reduced.

Further, as a well-known technique, the developing roller 8
A method may be considered in which a rotating stirring member is provided above 06 and the toner supply roller 807, and the stirring member is used to rub the toner. However, in this case, a drive mechanism for rotating the stirring member is required. As a result, there is a problem that the device becomes complicated and the production cost becomes high.

The present invention has been made in view of the above problems, and in a developing device using a non-magnetic one-component toner, when the toner is consumed in a large amount or the device is used in a high humidity environment. An object of the present invention is to provide a developing device and an image forming apparatus capable of efficiently charging a toner with a simple structure without deteriorating the toner even when operated.

[0036]

In order to solve the above-mentioned problems, the developing device according to the present invention includes a developer carrying means for applying a non-magnetic one-component developer to a photoconductor and a developer carrying means adjacent to the developer carrying means. The developer contact means is provided at a position where the reflux of the developer formed by the rotation of the developer supply means arranged in the above position passes, and the developer contact means for charging the developer by contact with the developer is provided.

As a result, the charging efficiency of the developer is increased by increasing the opportunity of triboelectric charging of the developer, so that the charge of the developer can be increased in a short time without causing deterioration of the developer. Therefore, even when printing a document with a high image ratio such as a solid image or a photographic image in which a large amount of developer is consumed, it is possible to prevent image defects such as fog and density decrease, and developer scattering. Meanwhile, a high quality output image can be obtained.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION A developing device according to a first aspect of the present invention is the same as a developer carrying means for rotating in a fixed direction and applying a non-magnetic one-component developer to a photosensitive member. Developer supply means that rotates in a direction and charges the developer by friction at the contact surface with the developer support means, and the reflux of the developer formed by rotation of the developer support means and the developer supply means. Is disposed at a position where the developer passes, and a developer contact unit that charges the developer by contact with the developer during the reflux motion is provided.

According to this structure, the developer is charged by contact with the developer during the reflux operation at a position where the reflux of the developer formed by the rotation of the developer carrying means and the developer supplying means passes. By disposing the agent contact means, it is possible to increase the opportunity of frictional electrification of the developer and shorten the time required for electrifying the developer during the reflux movement. As a result, even when a document with a high image ratio such as a solid image or a photographic image, which consumes a large amount of developer, is printed, the charge of the toner in the developing device is increased in a short time, and image defects such as fog or development occur. It is possible to prevent the agent from scattering.

A second aspect of the present invention is the developing device according to the first aspect, wherein the developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back. Therefore, a structure having a plurality of openings on the surface of the elongated body is adopted.

According to this structure, the developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to the direction in which the developer flows back, and a plurality of openings are formed on the surface of the elongated body shape. By including the portion, a large amount of the developer comes into contact with the developer contact means during the circulation movement of the developer, so that the opportunity of triboelectric charging of the developer can be increased. As a result, the time required for charging the developer during the reflux motion can be shortened. Further, since the developer is passed through the plurality of openings, the stirring property can be improved without hindering the reflux movement.

According to a third aspect of the present invention, in the developing device according to the second aspect, the plurality of openings have a structure in which a region facing the inside of the reflux is opened.

According to this structure, the flow resistance in the recirculation movement of the developer can be reduced, and the stagnation of the developer can be prevented.

A fourth aspect of the present invention is the developing device according to the second or third aspect, wherein at least a part of the plurality of openings has a larger contact surface area with the developer than the other openings. Take the composition.

According to this structure, when the developer passes through the opening of the developer contact means, it is possible to enhance the charging effect of the developer passing through the opening where the chance of contacting the opening increases. At the same time, the flow resistance of the developer passing through the other openings can be reduced. Therefore, the charging effect and the stirring effect can be simultaneously enhanced.

A fifth aspect of the present invention is the developing apparatus according to any one of the second to fourth aspects, wherein the plurality of openings are arranged with their opening surfaces facing the developer carrying means. Take the composition.

According to this structure, since the plurality of openings are opened to the side of the developer carrying means which is the drive source of the reflux flow of the developer, the developer easily enters the openings, and the developing It is possible to avoid a decrease in the flow of the developer when it comes into contact with the agent contact means.

According to a sixth aspect of the present invention, in the developing device according to the fifth aspect, the opening areas of the plurality of openings on the inlet side in the traveling direction of the developer are larger than those on the outlet side. Take.

According to this structure, the developer can be easily taken into the opening from a wide range, and the developer staying near the inlet of the opening can be reduced.
Further, by making the opening area at the outlet of the opening smaller than that at the inlet, the flow rate of the developer can be increased and the backflow of the developer can be prevented. As a result, the developer can be made to flow smoothly.

A seventh aspect of the present invention is the developing device according to any one of the second to sixth aspects, wherein the plurality of openings are formed in the vicinity of the longitudinal end of the developer contact means. The opening area of the formed opening is larger than the opening area of the opening formed near the central portion.

According to this structure, the flow resistance in the vicinity of the end of the developer contact means can be reduced, so that the resistance generated when the developer comes into contact with the inner wall of the developing chamber containing the developer. In addition, it is possible to avoid a situation where the flow state of the developer deteriorates. This makes it possible to average the flow rate of the developer in the vicinity of the end portion and in the vicinity of the central portion in the developer contact means, so that it is possible to prevent the developer from being offset.

According to an eighth aspect of the present invention, in the developing device according to any one of the first to seventh aspects, the layer thickness of the developer on the developer carrying means is regulated, and the developer is being refluxed. It is configured to include a layer thickness regulating member that charges the developer by contact with the developer.

According to this structure, it is possible to maintain a constant amount of the developer fed to the developing area arranged downstream of the developer carrying means and to increase the chance of frictional charging of the developer. it can. As a result, the time required for charging the developer during the reflux motion can be further shortened.

A ninth aspect of the present invention is the developing device according to the first aspect, wherein the developer contact means is formed when the amount of the developer accumulated in the main assembly of the apparatus exceeds a predetermined amount. The configuration is such that it is placed at two positions through which

According to this structure, by disposing the developer contact means at two positions through which the reflux formed when the developer exceeds the predetermined amount passes, the developer of the predetermined amount or more is provided in the apparatus. The opportunity for triboelectrification of the developer in the case of accumulation can be further increased. As a result, the time required for charging the developer during the reflux motion can be further shortened.

In a tenth aspect of the present invention, in the developing device according to the ninth aspect, one of the developer contact means is arranged in the vicinity of the starting point of the reflux of the developer, and the other is the reflux of the developer. The configuration arranged in the second half area is adopted.

According to this structure, by disposing one of the developer contact means in the vicinity of the starting point of the reflux of the developer, the developer contacts the developer contact means even when the remaining amount of the developer becomes small. They can be brought into contact with each other and can be reliably charged. Further, by arranging the other in the latter half region of the developer reflux, when the predetermined amount or more of the developer is accumulated in the apparatus, the chance of frictional charging of the developer existing in the latter half region of the reflux motion is increased. be able to. Therefore, even when a predetermined amount or more of the developer is accumulated, the time required for charging can be shortened.

The eleventh aspect of the present invention is the ninth or tenth aspect.
In the developing device according to the aspect, when the developer is replenished in the main body of the device, a configuration in which the amount exceeds a predetermined amount is adopted.

According to this structure, the developer contact means is arranged in the latter half region of the circulation of the developer formed in the apparatus when the developer is replenished in the apparatus. Therefore, the charging effect can be improved according to the amount of the developer when the developer is replenished.

The twelfth aspect of the present invention is the ninth to eleventh aspects.
In the developing device according to any one of the aspects, the developer contact unit has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back, and the surface of the elongated body shape. A structure having a plurality of openings is adopted.

According to this structure, a large amount of the developer comes into contact with the developer contact means during the recirculation movement of the developer, so that it is possible to increase the chances of frictional charging of the developer. As a result, the charge buildup of the developer during the reflux motion can be accelerated. Further, since the developer is passed through the plurality of openings, the stirring property can be improved without hindering the reflux movement.

The thirteenth aspect of the present invention relates to the tenth to first aspects.
In the developing device according to any one of aspects 2, the opening of the one developer contact unit arranged in the vicinity of the starting point of the circulation of the developer has the opening of the other developing unit arranged in the latter half region of the circulation of the developer. The configuration is larger than the opening of the agent contact means.

According to this configuration, the opening of the developer contact means on the side of the starting point of the recirculation movement of the developer, that is, on the upstream side of the recirculation movement is enlarged, so that the fluidity of the developer passing through the opening is secured. At the same time, it is possible to prevent the developer from staying while improving the charging effect.

The fourteenth aspect of the present invention relates to the first to thirteenth aspects.
In the developing device according to any one of the above aspects, the surface of the developer contact unit has conductivity.

According to this structure, the surface of the developer contact means is not charged by friction with the developer, and the electric charge can always be stably applied.

A fifteenth aspect of the present invention is the developing device according to the fourteenth aspect, in which the developer contact means is in a state in which it is grounded or a voltage can be applied.

According to this structure, the potential of the surface of the developer contacting means can be stabilized by grounding the developer contacting means, and the electric charge can always be stably applied. Further, by applying a voltage to the developer contact means, an electric field that accelerates the flow of the developer is generated, and the effect of imparting charge can be improved.

The image forming apparatus according to the sixteenth aspect of the present invention rotates in a fixed direction to apply a non-magnetic one-component developer to the photoconductor, and a developer carrying means that rotates in the same direction as the developer carrying means. Then, the developer supplying means for charging the developer by friction at the contact surface with the developer carrying means and the reflux of the developer formed by the rotation of the developer carrying means and the developer supplying means pass through. And a developer contact unit that is placed at a position to charge the developer by contact with the developer during the reflux motion.

According to this structure, the developer is charged by contact with the developer during the reflux operation at a position where the reflux of the developer formed by the rotation of the developer carrying means and the developer supplying means passes. By disposing the agent contact means, it is possible to increase the opportunity of frictional electrification of the developer and shorten the time required for electrifying the developer during the reflux movement. As a result, even when a document with a high image ratio such as a solid image or a photographic image, which consumes a large amount of developer, is printed, the charge of the toner in the developing device is increased in a short time, and image defects such as fog or development occur. It is possible to prevent the agent from scattering.

A seventeenth aspect of the present invention is the image forming apparatus according to the sixteenth aspect, wherein the developer contact means has a long body having a longitudinal direction in a direction substantially orthogonal to the direction in which the developer flows back. A configuration is adopted in which a plurality of openings are formed on the surface of the elongated body shape.

According to this structure, the developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to the direction in which the developer flows back, and a plurality of openings are formed on the surface of the elongated body shape. By including the portion, a large amount of the developer comes into contact with the developer contact means during the circulation movement of the developer, so that the opportunity of triboelectric charging of the developer can be increased. As a result, the charge buildup of the developer during the reflux motion can be accelerated. Also, since the developer passes through a plurality of openings,
Stirrability can be improved without disturbing the reflux motion.

An eighteenth aspect of the present invention is the image forming apparatus according to the seventeenth aspect, wherein the plurality of openings have a structure in which an area facing the inside of the circulation is opened.

According to this structure, the flow resistance in the recirculation motion of the developer can be reduced and the developer can be prevented from staying.

The nineteenth aspect of the present invention is the seventeenth or first aspect.
In the image forming apparatus according to the eighth aspect, at least a part of the plurality of openings has a larger contact surface area with the developer than other openings.

According to this structure, when the developer passes through the opening of the developer contact means, it is possible to enhance the charging effect of the developer passing through the opening where the chance of contacting the opening increases. At the same time, the flow resistance of the developer passing through the other openings can be reduced. Therefore, the charging effect and the stirring effect can be simultaneously enhanced.

The twentieth aspect of the present invention is from the seventeenth to first aspects.
In the image forming apparatus according to any one of the ninth aspect, the plurality of openings are arranged such that their opening surfaces face the developer carrying unit.

According to this structure, since the plurality of openings are opened to the side of the developer carrying means which is the driving source of the reflux flow of the developer, the developer easily enters the opening, and the developing It is possible to avoid a decrease in the flow of the developer when it comes into contact with the agent contact means.

In a twenty-first aspect of the present invention, in the image forming apparatus according to the twentieth aspect, the opening areas of the plurality of openings on the inlet side in the traveling direction of the developer are larger than those on the outlet side. Take the composition.

With this structure, the developer can be easily taken into the opening from a wide range, and the amount of the developer staying near the inlet of the opening can be reduced.
Further, by making the opening area at the outlet of the opening smaller than that at the inlet, the flow rate of the developer can be increased and the backflow of the developer can be prevented. As a result, the developer can be made to flow smoothly.

The twenty-second aspect of the present invention is based on the seventeenth to second aspects.
In the image forming apparatus according to any one of the first aspect, among the plurality of openings, the opening area of the opening formed near the longitudinal end of the developer contact unit is formed near the center. A structure larger than the opening area of the opening is adopted.

According to this structure, the flow resistance in the vicinity of the end portion of the developer contact means can be reduced, so that the resistance generated when the developer comes into contact with the inner wall of the developing chamber containing the developer. In addition, it is possible to avoid a situation where the flow state of the developer deteriorates. This makes it possible to average the flow rate of the developer in the vicinity of the end portion and in the vicinity of the central portion in the developer contact means, so that it is possible to prevent the developer from being offset.

The twenty-third aspect of the present invention is the sixteenth to second aspects.
In the image forming apparatus according to any one of aspects 2, the layer thickness of the developer on the developer carrying unit is regulated, and the developer is charged by contact with the developer during the reflux motion. A structure including members is adopted.

According to this structure, the amount of the developer fed to the developing area disposed downstream of the developer carrying means can be kept constant, and the chance of frictional charging of the developer can be increased. it can. As a result, the time required for charging the developer during the reflux motion can be further shortened.

A twenty-fourth aspect of the present invention is the image forming apparatus according to the sixteenth aspect, wherein the developer contact means is formed when the amount of the developer accumulated in the apparatus main body exceeds a predetermined amount. It adopts a configuration in which it is arranged at two positions through which the reflux flows.

According to this structure, by disposing the developer contact means at two positions where the reflux formed when the developer exceeds the predetermined amount passes, the developer of a predetermined amount or more is provided in the apparatus. The opportunity for triboelectrification of the developer in the case of accumulation can be further increased. As a result, the time required for charging the developer during the reflux motion can be further shortened.

A twenty-fifth aspect of the present invention is the image forming apparatus according to the twenty-fourth aspect, wherein one of the developer contact means is arranged near the starting point of the reflux of the developer, and the other is the reflux of the developer. The configuration is arranged in the latter half area of.

According to this structure, by disposing one of the developer contact means in the vicinity of the starting point of the reflux of the developer, the developer contacts the developer contact means even when the remaining amount of the developer becomes small. They can be brought into contact with each other and can be reliably charged. Further, by arranging the other in the latter half region of the developer reflux, when the predetermined amount or more of the developer is accumulated in the apparatus, the chance of frictional charging of the developer existing in the latter half region of the reflux motion is increased. be able to. Therefore, even when a predetermined amount or more of the developer is accumulated, the time required for charging can be shortened.

The twenty-sixth aspect of the present invention is the twenty-fourth or second aspect.
In the image forming apparatus according to the fifth aspect, when the developer is replenished in the apparatus main body, a configuration in which the predetermined amount is exceeded is adopted.

According to this structure, the developer contact means is arranged in the latter half region of the circulation of the developer formed in the apparatus when the developer is replenished in the apparatus. Therefore, the charging effect can be improved according to the amount of the developer when the developer is replenished.

The twenty-seventh aspect of the present invention is the twenty-fourth to second aspects.
In the image forming apparatus according to any one of the sixth aspect, the developer contact unit has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back, and the elongated body shape. A structure having a plurality of openings on its surface is adopted.

According to this structure, a large amount of the developer comes into contact with the developer contact means during the recirculation movement of the developer, so that it is possible to increase the chance of triboelectric charging of the developer. As a result, the charge buildup of the developer during the reflux motion can be accelerated. Further, since the developer is passed through the plurality of openings, the stirring property can be improved without hindering the reflux movement.

The twenty-eighth aspect of the present invention is the twenty-fifth to second aspects.
In the image forming apparatus according to any one of aspects 7, the opening of one of the developer contacting means arranged in the vicinity of the starting point of the circulation of the developer has the opening of the other of the other portions arranged in the latter half area of the circulation of the developer. The configuration is larger than the opening of the developer contact means.

According to this structure, the opening of the developer contact means on the side of the starting point of the recirculation movement of the developer, that is, on the upstream side of the recirculation movement is enlarged, so that the fluidity of the developer passing through the opening is secured. At the same time, it is possible to prevent the developer from staying while improving the charging effect.

The twenty-ninth aspect of the present invention is the sixteenth to second aspects.
In the image forming apparatus according to any one of the aspects 8, the surface of the developer contacting means has conductivity.

According to this structure, the surface of the developer contact means is not charged due to friction with the developer, and the electric charge can always be stably applied.

A thirtieth aspect of the present invention is the image forming apparatus according to the twenty-ninth aspect, in which the developer contact means is in a state in which it is grounded or a voltage can be applied.

According to this structure, the potential of the surface of the developer contact means can be stabilized by grounding the developer contact means, and the electric charge can always be stably applied. Further, by applying a voltage to the developer contact means, an electric field that accelerates the flow of the developer is generated, and the effect of imparting charge can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a side sectional view showing an internal structure of a developing device 100 according to Embodiment 1 of the present invention. The developing device 100 is applied to an image forming apparatus such as a copying machine or a multifunction peripheral.

As shown in FIG.
A toner storage chamber 101 for accumulating toner supplied from a toner bottle (not shown) and the toner storage chamber 101.
And a developing chamber 102 continuously provided below the developing chamber 102.

FIG. 1 shows the case where the toner 103 is supplied to the toner containing chamber 101 and the developing chamber 102. In this embodiment, a non-magnetic one-component toner having a negative polarity is used as the toner 103.

On the bottom surface of the toner storage chamber 101, a passage port 104 for supplying the accumulated toner 103 to the developing chamber 102.
Are formed. The developing chamber 1 is provided above the passage port 104.
A shutter 105 is provided to control the amount of toner 103 sent to 02.

The shutter 105 is configured to be rotatable in the direction of arrow A in the figure from the initial state shown in the figure.
When the shutter 105 is retracted from the passage opening 104, the toner 103 accumulated in the toner storage chamber 101 drops into the developing chamber 102. The shutter 105 is controlled by a drive mechanism (not shown) so that the toner amount in the developing chamber 104 does not become excessive and the shutter 105 does not run short.

The developing chamber 102 includes a developing roller 106, a toner supply roller 107, and a toner layer thickness regulating blade 108.
Is equipped with. The developing chamber 102 uses these configurations to charge the toner 103 that has fallen from the toner storage chamber 101, and at the same time, to the toner 10 on the surface of the developing roller 106.
3 is carried in a thin layer to carry a constant amount to a developing area described later.

The toner supply roller 107 rotates in the direction of the arrow Y in the drawing, and the toner 10 that has fallen from the passage port 104.
3 is conveyed to the developing roller 106 with the surface thereof included. The developing roller 106 rotates in the direction of the arrow X in the drawing, and conveys the toner 103 supplied from the toner supply roller 107 to the developing area. The toner layer thickness regulating blade 108 equalizes the layer thickness of the toner 103 attached to the developing roller 106,
To prevent a certain amount or more of toner 103 from being conveyed to the developing area. Hereinafter, each configuration will be specifically described.

The developing roller 106 has a volume resistivity of 10
A medium resistance elastic body such as urethane rubber or silicon rubber adjusted to about ⁷ Ω · cm to ^{10 10} Ω · cm is molded around a metal shaft and then ground into a cylindrical shape. As a method for imparting conductivity to rubber, it is usual to add an ion conductivity imparting agent and an electron conductivity filler. Examples of the electronic conductive filler include conductive carbon such as Ketchan black and acetylene black, carbon for various rubbers, conductive metal particles and conductive metal oxide particles. Examples of the ion conductive agent include perchlorates, ammonium salts, alkali metals and the like.

In this embodiment, a silicon rubber roller is used as the developing roller 106, and the rubber hardness is 60 ° according to JIS-A. Although not shown here, it is arranged so as to come into contact with a photosensitive drum described later by light pressure by the action of a pressing member such as a spring.

As the toner supply roller 107, a sponge roller in which a sponge such as urethane foam rubber or silicon foam rubber is formed into a cylindrical shape around a metal shaft is used. Each bubble on the surface of the sponge is adjusted to be larger than the toner particle size, and the toner 103 is conveyed on the surface.

The sponge used for the toner supply roller 107 may have either a single-cell structure or an open-cell structure. When a single-foam sponge roller is used, the proportion of bubbles tends to be low and the hardness tends to be high. Therefore, a low hardness material such as silicone rubber is used.

When a single-foam sponge roller is used, the bubbles on the surface of the sponge roller do not communicate with the inside. In other words, since the toner 103 is held only by the bubbles on the surface, the toner supply performance to the developing roller 106, particularly the performance (following performance) of supplying toner one after another when a large amount of toner is consumed, is slightly smaller than the continuous foaming property. Tends to be inferior.

On the other hand, when the continuous foam sponge roller is used, since the bubbles on the surface of the sponge roller communicate with the inside, a material such as urethane rubber having a relatively high hardness is used. .

When a continuous foam sponge roller is used, the toner 103 is accumulated in the bubbles communicating from the surface to the inside. Therefore, the followability of the toner supply performance is better than that of the single bubble property. However, a phenomenon may occur in which the toner 103, which has entered the bubbles communicating from the surface to the inside, gradually enters the inside, and the sponge hardness becomes hard when used for a long time.

The selection of the open-cell property and the open-cell property is determined by the developing conditions and the like. In the present embodiment, the followability of the toner supply performance is prioritized, and a continuous foam urethane sponge is selected for the toner supply roller 107. Rubber hardness is A
Approximately 60 ° with a ker-F hardness tester (manufactured by Kobunshi Keiki Co., Ltd.)
The hardness of the surface of the developing roller 106 is about 1 mm at the contact position with the developing roller 106.

Developing roller 106 and toner supply roller 10
The toner layer thickness regulating blade 108 is disposed at a position slightly downstream of the contact position with the developing roller 106 in the rotation direction of the developing roller 106. As shown in the figure, the toner layer thickness regulating blade 108 has one end fixed to the end of the housing of the developing chamber 102, the other end extending in the direction of the toner supply roller 107, and the peripheral surface of the developing roller 106. They are arranged so that they come into contact with each other at a constant pressure.

The toner layer thickness regulating blade 108 is made of a stainless thin plate spring material having a thickness of about 0.1 mm, and is arranged so as to bite in about 1 mm from the surface of the developing roller 106 at the contact position with the developing roller 106. A linear pressure of about 30 gf / cm at the contact portion is realized.

In this embodiment, the tip of the toner layer thickness regulating blade 108 on the side of the developing roller 106 is bent into an L shape. This maintains linearity in the longitudinal direction. Further, the toner layer is regulated to form a layer by bringing the leading end bent into an L shape into contact with the developing roller 106. This prevents the toner layer thickness unevenness on the developing roller 106 in the longitudinal direction from occurring.

In the present embodiment, a stainless thin leaf spring material is used as the toner layer thickness regulating blade 108.
However, the present invention is not limited to this, and a leaf spring material such as phosphor bronze can also perform the same function. Instead of bending the tip of the toner layer thickness regulating blade 108 into an L-shape, an elastic member such as urethane rubber or silicon rubber is arranged at the tip by adhesion or injection molding, and that portion is formed on the surface of the developing roller 106. By bringing them into contact with each other, it is possible to make the contact pressure uniform in the longitudinal direction and prevent toner layer thickness unevenness from occurring.

In this embodiment, the contact state between the developing roller 106 and the toner supply roller 107 and the contact pressure between the developing roller 106 and the toner layer thickness regulating blade 108 are set as described above. However, the setting is not limited to these, and is preferably set according to matching with the toner 103 or the like.

That is, the contact state between the developing roller 106 and the toner supply roller 107 and the contact pressure between the developing roller 106 and the toner layer thickness regulating blade 108 are matched with the toner 103, particularly, the deterioration resistance and the charging performance of the toner 103. It should be set together.

That is, if the contact pressure between the developing roller 106 and the toner supply roller 107 and the contact pressure between the developing roller 106 and the toner layer thickness regulating blade 108 are increased, the toner 1
The charging efficiency of 03 is temporarily increased. However, the toner deterioration is accelerated and the fluidity is deteriorated.
No. 3 results in poor charging. On the other hand, if the contact pressure is too low, the necessary charge amount cannot be applied to the toner 103. Therefore, these states are preferably set according to the matching with the toner 103 used in the apparatus.

A power source 109 is connected to the metal shaft of the developing roller 106, the metal shaft of the toner supply roller 107, and the toner layer thickness regulating blade 108. The power source 109 is a DC-3 connected to these connection destinations during development.
A developing bias of 00v is applied.

Above the toner layer thickness regulating blade 108,
A toner contact member 110 is arranged. Specifically, the toner contact member 110 is arranged at the passage position of the toner flowing along the recirculation (hereinafter referred to as “toner recirculation”) generated by the rotation of the developing roller 106 and the toner supply roller 107. The toner contact member 110 has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to the toner circulation direction. The details of this toner circulation will be described later.

The toner contact member 110 is made of a rigid metal material such as a stainless steel plate or a plated steel plate. In the present developing device 100, by disposing such a metal rigid body at the passage position of the toner 103, the toner 10
Increasing the chance of triboelectric charging of No. 3.

A power source 111 is connected to the toner contact member 110. The power supply 111 applies a predetermined voltage to the toner contact member 110. As a result, the toner contact member 111
It is possible to stabilize the surface potential of, and it is possible to always stably provide the electric charge. The toner contact member 11
In order to stabilize the surface potential of No. 1, the electric charge accumulated in the toner contact member 111 may be released by grounding it.

A negative photosensitive drum 112 is arranged at a position in contact with the peripheral surface of the developing roller 106. The photoconductor drum 112 rotates in the direction of arrow B in the figure, and adheres the toner 103 supplied from the developing roller 106 to the electrostatic latent image formed on the peripheral surface. As a result, the electrostatic latent image formed on the peripheral surface is visualized.

In this embodiment, a metal cylindrical body of aluminum or the like is used as a base material, and an organic photoconductor (hereinafter referred to as "OPC") is formed in a thin film on the outer peripheral surface thereof. Of course, instead of OPC, it is also possible to use amorphous silicon (a-Si), selenium (Se), or the like.

Adjacent to the photoconductor drum 112, a corona charger 113 for charging the surface of the photoconductor drum 112 and an exposure device 114 for exposing the charged surface of the photoconductor drum 112 according to image data are arranged. Has been done.

The corona charger 113 sets the surface potential of the photosensitive drum 112 to -600v to -900v in a dark place.
It is charged to a potential (dark area potential). The corona charger 113 has a configuration in which a corona generation source such as a tungsten wire is surrounded by a metal shield, and a grit plate is arranged in the opening on the side of the photoconductor drum 112. Of course, as a means for charging the photosensitive drum 112, the corona charger 11
Instead of 3, a charging member such as a charging roller or a charging brush can be used.

The exposure device 114 is a semiconductor laser or LED.
An electrostatic latent image is formed on the surface of the photoconductor drum 112 by using the array as an exposure source and turning these exposure sources on and off based on image data to be printed.

The exposed portion on the photosensitive drum 112 drops to a potential (bright portion potential) of about -50v to -100v. As a result, an electrostatic latent image corresponding to a print image is formed on the photoconductor drum 112, which includes a dark potential portion which is a non-printed portion of image data and a bright potential portion which is a printed portion.

Developing device 100 having the above-described structure
The developing operation will be described.

When the toner 103 is supplied from the toner storage chamber 101 to the developing chamber 102, the toner supply roller 107 includes the toner 103 in the vicinity on the surface of the sponge, and the arrow Y
Transport in the direction of. The developing roller 106 and the toner supply roller 107 rotate in opposite directions at their contact portions. Therefore, the toner 1 conveyed by the toner supply roller 107
03 is rubbed between the two to be charged. As a result, the toner 103 is negatively charged and simultaneously adheres to the surface of the developing roller 106 by the image force.

The toner 103 adhering to the surface of the developing roller 106 is evened by the toner layer thickness regulating blade 108, and at the same time, is rubbed against the contact surface of the toner layer thickness regulating blade 108 to be further charged. The toner 103 has a thickness of 2 to 5 due to the toner layer thickness regulating blade 108.
The toner layer is regulated by a layer of charged toner. Then, it is carried to a developing area constituted by a contact portion between the developing roller 106 and the photosensitive drum 112.

On the other hand, on the surface of the photosensitive drum 112, an electrostatic latent image corresponding to the image data printed by the exposure device 114 is formed. The electrostatic latent image formed on the photoconductor drum 112 has a dark portion potential of about −800 v and a light portion potential of about −100 v, and the potential gradients of the light portion and the dark portion with respect to the developing roller 106 are in opposite directions. ing.

Since the toner 103 attached to the surface of the developing roller 106 holds a negative charge,
In the developing area, an electric field that directs the toner 103 toward the photoconductor drum 112 is generated in the light potential portion of the electrostatic latent image on the photoconductor drum 112. On the other hand, in the dark potential area, toner 1
An electric field is generated to direct 03 toward the developing roller 106.

Therefore, the toner 103 is applied to the developing roller 10 according to the electrostatic latent image corresponding to the image data in the developing area.
It flies from 6 and adheres to the photoconductor drum 112. As a result, the electrostatic latent image is visualized and a toner image is formed on the surface of the photoconductor drum 112.

Next, the developing device 100 according to the first embodiment.
The toner recirculation inside the developing chamber 102 will be described. FIG. 2 is an enlarged view around the developing chamber 102 of the developing device 100 according to the first embodiment.

In the developing chamber 102, the developing roller 106
And the toner supply roller 107 are respectively in the direction of arrow X,
It is rotating in the Y direction. Due to the action of the rotation of these rollers, the toner recirculation R occurs in the toner 103 in the developing chamber 102 as indicated by the circular arrow in the figure.

That is, the toner 103 near the toner supply roller 107 and on the upper left side passes above the contact surface between the developing roller 106 and the toner supply roller 107, and moves near the developing roller 106 and above the right side. And
It rises along the inclination of the toner layer thickness regulating blade 108. Then, after the toner has risen to some extent, this time, the toner recirculation R that changes the moving direction to the right and returns to the upper left side near the toner supply roller 107 is generated.

In such a toner recirculation R, the toner 103 is charged by coming into contact with each member in the developing chamber 102. In particular, the toner layer thickness regulating blade 108 has a fixed end above the developing roller 106 and a front end extending toward the toner supply roller 107. As a result, the toner 103 is transferred to the toner layer thickness regulating blade 10
The surface of No. 8 is contacted, and it is made to flow along it. For this reason, the toner recirculation R is made smoother, and the chances of friction of the toner 103 are increased, thereby exerting an effect of charging.

In the developing device 100, the toner recirculation R
The toner 10 which is in the position where
A toner contact member 110 that charges the toner 103 by contacting the toner 3 is provided in the developing chamber 102. As a result, the opportunity for triboelectric charging of the toner 103 is increased, and the time required for charging the toner 103 during the reflux movement is shortened.

In the main developing device 100, as shown in FIG. 1, the power source 1 is applied to the developing roller 106 during the developing operation.
09, a developing bias of DC-300v is applied. On the other hand, a voltage of about DC-100v is applied to the toner contact member 110 by the power supply 111. As a result, an electric field that accelerates the toner 103 from the developing roller 106 toward the toner contact member 110 is generated, and the flow effect of the toner 103 is further enhanced.

An example of the structure of the toner contact member 110 used in the developing device 100 will be described below with reference to FIG. FIG. 3 is a perspective view showing an example of the configuration of the toner contact member 110 used in the developing device 100. As described above, the toner contact member 110 has the shape of an elongated body, but a part thereof is shown in each drawing of FIG.

As shown in FIG. 3, the toner contact member 110.
Is provided with a plurality of openings (notches) through which the toner 103 passes. 3 (a) to 3 (c) show the one having an opening, and FIGS. 3 (d) to 3 (g) show the one having a notch as the opening.
In addition, about FIG.3 (c), the opening part and the notch part are combined.

In this embodiment, the toner contact member 110 is used.
A plurality of openings or notches are formed in a rigid metal body such as a stainless steel plate or a plated steel plate having a thickness of about 0.5 to 2 mm by drilling, punching, laser processing, or the like.

In this way, the toner contact member 110 having a plurality of openings or notches as described above is arranged at the position where the toner reflux R passes. For this reason, the toner 103 that is in the recirculation motion is not transferred to the toner contact member 11.
After contacting 0, it passes through an opening or the like. As a result, the chances of triboelectric charging of the toner 103 are increased, so that the time required for charging the toner 103 during the reflux movement can be shortened.

Further, since the toner contact member 110 is formed with a plurality of openings and the like, the fluidity of the toner 103 is secured. For this reason, a part of the toner 103 contacts the toner contact member 110 and temporarily stays, while a part of the toner 103 passes through the opening or the like without staying as it is.
Therefore, it is possible to improve the stirring property of the toner 103 while ensuring the fluidity of the toner 103 in the developing chamber 102.

The toner contact member 110 having the cutout portions shown in FIGS. 3C to 3G has one end on the side where the cutout portion is formed (one end on the lower right side in FIG. 3). It is desirable to arrange it so as to face the inside of the toner circulation R. In other words, it is desirable to dispose the toner recirculation R inside so as to be opened at the notch.

By disposing the notch inside the toner recirculation R as described above, the flow resistance of the toner 103 inside the developing chamber 102 can be reduced. This can prevent the toner 103 from staying.

FIG. 4 is an enlarged view showing an example of the sectional configuration of the toner contact member 110 used in the developing device 100. In the present embodiment, a plurality of openings and the like formed in the toner contact member 110 are opened to the developing roller 106. Therefore, in FIG. 4, it is assumed that the developing roller 106 is arranged below each drawing. The arrow indicates the flow direction of the toner 103, and the size of the arrow indicates the flow amount of the toner 103. These cross-sectional shapes can be applied to each structural example shown in FIG.

As described above, in the present embodiment, the plurality of openings and the like formed in the toner contact member 110 are connected to the developing roller 1.
It is opened to 06. As a result, it is possible to avoid a decrease in the flow of the toner 103 when the toner 103 contacts the toner contact member 110.

FIG. 4A shows a case where a plurality of openings are formed in the toner contact member 110, and the openings are not particularly subjected to the treatment for improving the charging property, the fluidity or the stirring property. In this case, the toner 1 that has passed through the opening
03 goes straight upward as shown in the figure.

In FIGS. 4B and 4C, the contact surface area of the toner 103 on the inner wall surface of the specific opening is larger than that of the other openings. Specifically, the inner wall surface of the specific opening is chamfered or rounded. No processing was applied to the other openings.

With such a structure of the toner contact member 110, when the toner 103 passes through the specific opening, the chance of contact with the inner wall surface increases. Therefore, toner 1
No. 03 charging effect can be improved. Further, since the toner 103 goes straight ahead in the other openings, the fluidity of the toner 103 is secured.

The formation of the opening for increasing the charging effect of the toner 103 and the formation of the opening for ensuring the fluidity of the toner 103 play a great role in the stirring effect of the toner 103.

That is, the charging effect of the toner 103 cannot be expected at the opening for ensuring the fluidity of the toner 103.
However, by forming such an opening, a difference in speed of toner flow occurs. Due to the existence of the speed difference of the toner flow, minute vortices are generated at various places, and the minute vortices cause the toner 103 to be stirred. By repeating this, the toner particles come into contact with the toner contact member 11.
The chances of contacting 0 are even. As a result, it is possible to uniformly charge the toner particles.

As shown in FIGS. 4B and 4C,
It is preferable in the embodiment that the opening area of the other openings is larger than that of the specific opening. In this case, the charging effect in the specific opening and the stirring effect due to the difference in the flow speed of the toner 103 passing through the other openings can be further enhanced.

As a structure of the opening for promoting the stirring action of the toner 103, it is conceivable that the opening areas of the adjacent openings are different as shown in FIG. 4D. In this case, as shown in FIG. 4D, since the difference in the flow velocity of the toner 103 passing through each opening differs depending on the adjacent openings, it is expected that the stirring action is further improved.

Incidentally, in order to improve the fluidity of the toner in the vicinity of the opening of the toner contact member 110, it is necessary to carry out the process shown in FIG.
As shown in (g), it is effective to make the opening area on the inlet side of the toner 103 in the opening larger than the opening area on the outlet side. In this case, the toner 103 can be easily taken into the opening from a wide range, and
It is possible to reduce the amount of toner 103 staying near the entrance of the opening. Further, by making the opening area of the outlet of the opening smaller than that of the inlet, the flow velocity of the toner 103 can be increased and the backflow of the toner 103 can be prevented. As a result, the toner 103 can be made to flow smoothly.

The processing for increasing the opening area on the inlet side of the opening can be realized by various means. For example, the shape of the opening shown in FIG. This can be achieved by pressing a flat plate material.

In order to increase the fluidity of the toner 103, a low friction plated steel plate obtained by plating the surface of a steel plate forming the toner contact member 110 with a treatment liquid containing a solid lubricant such as molybdenum disulfide or graphite is used. Alternatively, it is preferable as an embodiment to coat the surface of the steel sheet with a low friction film such as fluororesin.

In FIGS. 4B and 4C, the contact surface area of the toner 103 on the inner wall surface of the specific opening is made larger than that of the other openings by a method such as chamfering. However, the toner contact member 110 is not limited to this.
As a method for increasing the contact area in the specific opening, a configuration as shown in FIG. 5 may be used.

FIG. 5 shows the toner 10 at a specific opening.
6 is a perspective view of another example of the toner contact member 110 when the contact area with respect to No. 3 is increased. FIG. In FIG. 5, the uneven portion is formed on the outer peripheral shape of the specific opening. in this case,
When passing through a specific opening, there is more chance of contact than other openings due to the inwardly projecting projection. For this reason,
The charging effect of the toner 103 can be improved.

Further, due to the protruding portion on the inner side, a finer vortex is generated in the toner 103 passing in the vicinity thereof. Due to the stirring action by the minute vortex, the toner 103
A uniform charging is realized.

Inside the developing chamber 102, a toner contact member 110 having the above-described structure and having a long body shape is disposed so as to face the toner layer thickness regulating blade 108. Here, the toner 1 inside the developing chamber 102
Comparing the flow state of No. 03, the wall surface has flow resistance on the side surface side (front side or back side shown in FIG. 1) of the developing chamber 102, and the flow state is worse than at the central portion.

When the flow state of the toner 103 inside the developing chamber 102 is left as it is, the toner 10
A situation may occur in which charging is not uniformly applied to No. 3. Therefore, in the present developing device 100, the opening area of the toner contact member 110 on the side surface side of the developing chamber 102 is made larger than the opening area near the central portion.

FIG. 6 is a perspective view of the toner contact member 110 showing an example in which the opening area on the side surface side of the developing chamber 102 is made larger than the opening area near the central portion. Figure 6
In (a), a case is shown in which the amount of toner 103 passing in the vicinity of the central portion is regulated as compared with the end portion on the side surface side. On the other hand, FIG. 6B shows the case where the passage amount of the toner 103 at the end portion on the side surface side is increased as compared with the vicinity of the central portion.

By constructing the opening of the toner contact member 110 in this way, inside the developing chamber 102,
The flow resistance on the side surface side of the toner contact member 110 is reduced to prevent the flow state of the toner 103 from being deteriorated due to the resistance generated when the inner wall of the developing chamber 102 in which the toner 103 is stored and the toner 103 contact each other. can do. As a result, the flow amount of the toner 103 on the side surface side and the central portion of the toner contact member 110 can be averaged, so that deviation of the toner 103 can be prevented and the toner 103 can be prevented from being displaced. The charge can be evenly applied.

As described above, according to the main developing device 100, the toner 1 is placed at the position where the toner recirculation R passes in the developing chamber 102.
Since the toner contact member 110 that charges the toner 103 by contacting the toner 03 with the contact contact member 03 increases the chance of frictional charging of the toner 103, the time required for the toner 103 to start charging during the reflux motion can be shortened. As a result, even when a document having a high image ratio such as a solid image or a photographic image in which a large amount of toner 103 is consumed is printed, the charging of the toner 103 in the developing chamber 102 is increased in a short time,
It is possible to obtain a high-quality output image while preventing image defects such as fog and density decrease and the occurrence of developer scattering.

Further, since the charging effect is improved by increasing the chances of frictional charging in the developing chamber 102, when the toner 103 is frictionally charged, the developing roller 106 and the toner supply roller 107 come into contact with each other. No need to increase pressure. For this reason, it is possible to shorten the time required for the charging to rise without accelerating the deterioration of the toner 103. Therefore, even when the toner 103 such as an oilless fixing color toner that is particularly sensitive to toner deterioration and has a slow charging rise is used, it is possible to reliably prevent the occurrence of image defects such as fog and density decrease.

In this embodiment, the case where a metal rigid body is used as the material of the toner contact member 110 has been described. However, the material is not limited to this, and a resin material such as ABS, polycarbonate, or nylon can also be used.
In this case, the toner contact member 110 having the opening having the complicated shape as described above can be easily formed by performing the processing by injection molding.

It is also possible to use a resin film such as PET or polyimide. In this case, the opening can be easily processed. When a resin film is used, the resin film is elastically deformed without countering the toner recirculation R in the developing chamber 102. Therefore, the resistance to the toner flow R can be reduced, and the smooth toner recirculation R can be realized.

It is also possible to use a polymer film for the toner contact member 110. When a polymer film is used, it is possible to change the charging characteristics of the film itself by subjecting the film to plasma treatment in advance. As a result, the efficiency of imparting charge to the toner can be improved.

Further, by using a resin material having a charging characteristic opposite to that of the toner for the surface or the whole of the toner contact member 110, it is possible to improve the charging performance for the toner. For example, for a negatively charged toner, a material having a positive charging characteristic such as nylon or a resin containing a charge control agent for a positive charging such as a quaternary ammonium salt compound is used to obtain a toner charging performance. Can be improved.

Further, except that the toner contact member 110 is formed of a conductor such as metal, a conductive film is formed on the surface of the resin by a thin film forming technique such as plating or PVD, or a conductive substance is contained in the resin. It can be realized by making the resin conductive by a method such as inclusion.
In this case, the toner contact member 11 during friction with the toner
It is possible to prevent the surface of 0 from being triboelectrically charged to a high potential. As a result, it is possible to prevent the repulsive force or attractive force from being generated on the toner due to the surface of the toner contact member 110 being triboelectrically charged at a high potential. Can be stabilized.

Further, in the present embodiment, the developing device 100 adopting the contact developing system in which the developing roller 106 made of silicon rubber or the like is disposed in contact with the photosensitive drum 112 is described. However, the present invention is not limited to this, and can also be applied to a non-contact developing system in which the developing roller 106 is arranged in non-contact with the photosensitive drum 112. Even in the developing device using such a non-contact developing method, the same effect as that of the present embodiment can be obtained.

(Second Embodiment) While the developing device 100 according to the first embodiment includes a single toner contact member in the developing chamber 102, the developing device 100 according to the second embodiment.
Are different in that two toner contact members are provided in the developing chamber 102. The developing device 100 according to the second embodiment has two
Since it has the same configuration as the developing device 100 according to the first embodiment except that it is provided with one toner contact member, the description thereof will be omitted.

FIG. 7 shows the developing device 10 according to the second embodiment.
FIG. 3 is an enlarged view around the developing chamber 102 of No. 0. FIG. 7A shows a case where the rotation axis of the toner supply roller 107 is arranged above the rotation axis of the developing roller 106.
(B) shows the case where the rotation axis of the toner supply roller 107 is arranged below the rotation axis of the developing roller 106.

When the amount of toner 103 accumulated in the developing chamber 102 exceeds a predetermined amount, a large amount of toner 103 is present in a region away from the developing roller 106 which is the starting point of the toner recirculation R, that is, in the latter half of the toner recirculation R. Will be accumulated. Here, the predetermined amount is, for example, the amount of toner when the toner 103 is replenished in the developing chamber 102.

For example, in the example shown in FIG. 7, a large amount of toner 103 is accumulated in a region S surrounded by a dotted line (hereinafter referred to as "second half region S"). The accumulation of the toner 103 in the latter half region S becomes particularly remarkable when the rotation axis of the developing roller 106 is arranged below the rotation axis of the toner supply roller 107 as shown in FIG. 7A.

When the developing roller 106 and the toner supply roller 107 start to rotate from the state where a certain amount of toner 103 is accumulated in the latter half area S, the toner 103 accumulated in the latter half area S is vigorously accumulated in the toner supply roller 107. It flows into the peripheral surface.

In consideration of the flow movement of the toner 103 when a predetermined amount of toner 103 or more is accumulated in the developing chamber 102, the developing device 100 according to the second embodiment is at a position where the toner recirculation R passes. Therefore, the second toner contact member is arranged inside the latter half area S. The arrangement of the first toner contact member is near the starting point of the toner recirculation R, as in the developing device 100 according to the first embodiment.

Specifically, as shown in FIGS. 7A and 7B, at a position where the toner recirculation R formed in the developing chamber 102 passes when the toner 103 of a predetermined amount or more is accumulated. Therefore, the first toner contact member 701 is arranged near the upper part of the developing roller 106. In addition, the second position is provided at a position where the toner recirculation R passes and which is inside the second half region S.
A toner contact member 702 is arranged.

A predetermined amount or more of toner 10 is placed in the developing chamber 102.
When the developing roller 106 and the toner supply roller 107 start to rotate from the state where 3 is accumulated, the toner 103 accumulated in the second half region S contacts the second toner contact member 702 according to the toner recirculation R. Then, it is charged by friction with the second toner contact member 702.

As the first and second toner contact members 701 and 702, the toner contact members having various opening shapes described in the first embodiment can be applied. By applying the toner contact member as described in the first embodiment, it is possible to efficiently apply the charge to the toner.

As described above, the developing device 1 according to the second embodiment
00, a predetermined amount of toner 10 or more in the developing chamber 102
Toner contact members 701 and 702 are arranged at two positions through which the toner recirculation R formed when 3 is accumulated. As a result, as compared with the case where the toner contact developer is arranged only in one place as in the first embodiment, the opportunity of triboelectric charging can be further increased. As a result, it is possible to further shorten the time required for the charging of the toner 103 to rise during the reflux movement.

Further, the developing device 100 according to the second embodiment.
Then, while the toner contact member 701 is arranged in the vicinity of the starting point of the toner recirculation R, the toner contact member 702 is arranged near the toner recirculation R.
It is arranged inside the latter half region S of. As a result, when the remaining amount of the toner 103 is low, the toner 103 can be surely charged by contacting the toner contact member 701, while a predetermined amount or more of the toner 103 is accumulated in the developing chamber 102. In this case, it is possible to increase the chances that the toner 103 accumulated in the second half region S of the reflux movement is triboelectrically charged. As a result, even if the toner 103 of a predetermined amount or more is accumulated in the developing chamber 102, the toner 10
It is possible to shorten the time required for the charging of No. 3 to rise.

Further, the developing device 10 according to the second embodiment.
In 0, the opening area of the opening of the first toner contact member 701 is larger than the opening area of the opening of the second toner contact member 702. As a result, the toner 1 that can be generated by reducing the opening of the first toner contact member 701
03 can be prevented, so that the toner 103
It is possible to improve the charging effect while ensuring the fluidity.

[0189]

As described above, according to the present invention,
In a developing device using a non-magnetic one-component toner, toner recirculation is formed above the toner supply roller and the developing roller by the toner conveying force from the toner supply roller toward the developing roller, and friction occurs at the position where the toner recirculation passes. Is provided with a toner contact member for charging the toner. This increased the chances of toner tribocharging,
Even when a large amount of toner is consumed or when the apparatus is operated in a high humidity environment, the toner is not deteriorated and the toner can be highly efficiently charged with a simple configuration. Further, even when a document with a high image ratio such as a solid image or a photographic image, which consumes a large amount of developer, is printed, the toner charge in the developing device is increased in a short time, resulting in image defects such as fog and density decrease It is possible to obtain a high-quality output image while preventing the occurrence of the developer scattering and the like.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an internal structure of a developing device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view around a developing chamber of the developing device according to the first embodiment.

FIG. 3 is a perspective view showing an example of the configuration of a toner contact member used in the developing device according to the first embodiment.

FIG. 4 is an enlarged view showing an example of a cross-sectional configuration of a toner contact member used in the developing device according to the first embodiment.

FIG. 5 is a perspective view of a toner contact member of another example provided in the developing device according to the first embodiment when the contact area with respect to toner in a specific opening is increased.

FIG. 6 is a perspective view of a toner contact member showing an example in which the opening area on the side surface side of the developing chamber is larger than the opening area near the central portion, which is included in the developing device according to the first embodiment.

FIG. 7 is an enlarged view around a developing chamber of the developing device according to the second embodiment of the present invention.

FIG. 8 is a side sectional view showing the internal structure of a conventional developing device.

FIG. 9 is a graph showing the charge rising characteristics of toner.

[Explanation of symbols]

100 developing device 101 toner storage chamber 102 development room 103 toner 106 developing roller 107 toner supply roller 108 Toner Layer Thickness Control Blade 109,111 Power supply 110 Toner contact member 112 photoconductor drum 113 Corona charger 114 exposure equipment 701 First toner contact member 702 Second toner contact member

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Claims (30)

[Claims] 1. A developer carrying means that rotates in a fixed direction to apply a non-magnetic one-component developer to a photoconductor, and a contact surface that rotates in the same direction as the developer carrying means and is in contact with the developer carrying means. A developer supply unit that charges the developer by friction, and a developer that is disposed at a position through which the reflux of the developer formed by the rotation of the developer holding unit and the developer supply unit passes and which is in a reflux motion. And a developer contact unit that charges the developer by contact with the developing device. 2. The developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back, and a plurality of openings are formed on the surface of the elongated body shape. The developing device according to claim 1, further comprising: 3. The plurality of openings are open in a region facing inward of the reflux.
The developing device described. 4. At least a part of the plurality of openings is
4. The developing device according to claim 2, wherein a contact surface area with the developer is larger than that of the other openings. 5. The developing device according to claim 2, wherein the plurality of openings are arranged with their opening surfaces facing the developer carrying means. 6. The developing device according to claim 5, wherein the opening areas of the plurality of openings on the inlet side in the traveling direction of the developer are larger than the opening area on the outlet side. 7. The opening area of the opening formed near the end of the developer contact unit in the longitudinal direction of the plurality of openings is larger than the opening area of the opening formed near the central portion. The developing device according to any one of claims 2 to 6, wherein: 8. A layer thickness regulating member for regulating the layer thickness of the developer on the developer carrying means and charging the developer by contact with the developer during the reflux motion. The developing device according to any one of claims 1 to 7. 9. The developer contacting means is arranged at two positions through which reflux formed when the developer accumulated in the apparatus main body exceeds a predetermined amount passes. The developing device according to claim 1. 10. The developer contact means according to claim 9, wherein one of the developer contact means is disposed near a starting point of the reflux of the developer and the other is disposed in a second half region of the reflux of the developer. Development device. 11. The developing device according to claim 9, wherein the developer exceeds a predetermined amount when the developer is replenished in the main body of the device. 12. The developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back, and a plurality of openings are formed on the surface of the elongated body shape. The developing device according to any one of claims 9 to 11, characterized by having. 13. The opening of one of the developer contact means arranged near the starting point of the reflux of the developer is larger than the opening of the other developer contact means arranged in the latter half region of the reflux of the developer. Claim 10 to claim 1 characterized in that it is large.
2. The developing device according to any one of 2. 14. The developing device according to claim 1, wherein a surface of the developer contact unit has conductivity. 15. The developing device according to claim 14, wherein the developer contact unit is grounded or is in a state in which a voltage can be applied. 16. A developer carrying means that rotates in a fixed direction to apply a non-magnetic one-component developer to a photoconductor, and a contact surface that contacts the developer carrying means and rotates in the same direction as the developer carrying means. A developer supply unit that charges the developer by friction, and a developer that is disposed at a position through which the reflux of the developer formed by the rotation of the developer holding unit and the developer supply unit passes and which is in a reflux motion. And a developer contact unit that charges the developer by contact with the image forming apparatus. 17. The developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back, and a plurality of openings are formed on the surface of the elongated body shape. The image forming apparatus according to claim 16, further comprising: 18. The image forming apparatus according to claim 17, wherein an area of the plurality of openings facing the inner side of the circulation is open. 19. The image forming apparatus according to claim 17, wherein at least a part of the plurality of openings has a larger contact surface area with the developer than other openings. 20. The image forming apparatus according to claim 17, wherein the plurality of openings are arranged with their opening surfaces facing the developer carrying unit. 21. The image forming apparatus according to claim 20, wherein an opening area of the plurality of openings on an inlet side in a traveling direction of the developer is larger than an opening area on an outlet side thereof. 22. Of the plurality of openings, an opening area of an opening formed near an end portion in the longitudinal direction of the developer contact means is larger than an opening area of an opening formed near a central portion. 22. The image forming apparatus according to claim 17, wherein the image forming apparatus is an image forming apparatus. 23. A layer thickness regulating member for regulating the layer thickness of the developer on the developer carrying means and charging the developer by contact with the developer during reflux movement. The image forming apparatus according to any one of claims 16 to 22. 24. The developer contact means is arranged at two positions through which a reflux formed when the developer accumulated in the apparatus main body exceeds a predetermined amount passes. The image forming apparatus according to claim 16. 25. The developer contact means according to claim 24, wherein one of the developer contact means is arranged near a starting point of the reflux of the developer, and the other is arranged in a latter half region of the reflux of the developer. Image forming apparatus. 26. The image forming apparatus according to claim 24, wherein the developer exceeds a predetermined amount when the developer is replenished in the apparatus main body. 27. The developer contact means has an elongated body shape having a longitudinal direction in a direction substantially orthogonal to a direction in which the developer flows back, and a plurality of openings are formed on the surface of the elongated body shape. The image forming apparatus according to any one of claims 24 to 26, further comprising: 28. The opening of one of the developer contacting means arranged in the vicinity of the starting point of the reflux of the developer is larger than the opening of the other developer contacting means arranged in the latter half region of the reflux of the developer. Claim 25 to Claim 2 characterized in that it is large.
7. The image forming apparatus according to any one of 7. 29. The image forming apparatus according to claim 16, wherein the surface of the developer contact unit has conductivity. 30. The image forming apparatus according to claim 29, wherein the developer contact unit is in a grounded state or in a state in which a voltage can be applied.