JPH11167270A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly discharge developer to an image carrier regardless of environmental change by changing the degree of surface roughness in the rotary shaft direction of a developer carrier based on the supply distribution of the developer. SOLUTION: The coating amount of the developer on the developer carrier 10 is regulated by a blade 11, and a distance between a photoreceptor drum 2 and the carrier 10 is kept constant by a roller, then the carrier 10 has magnetic polarity consisting of four poles. By impressing bias consisting of AC and DC on the carrier 10, the developer is splashed to the drum 2. The developer is replenished from a developer replenishment port in accordance with a developer requiring signal by a piezoelectric sensor 13 and fed to the end on the inner side by a screw 14. A gutter 15 positioned downward is provided with a notch, so that the developer drops to developing chambers 6 and 7 any time and it reaches the carrier 10. In the drop distribution of the developer, the flow distribution of the developer is changed in accordance with environment, so that the developer supply distribution in the center part is reduced. Therefore, the degree of the surface roughness of the center part of the carrier 10 is made rough.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an image forming apparatus for an electrostatic transfer process such as a copying machine and a printer.

[0002]

2. Description of the Related Art Conventionally, this type of developing apparatus is applied to an image forming apparatus for an electrostatic transfer process such as a copying machine or a printer.

The developing device is composed of two developing chambers, and a stirring bar is disposed in each of the developing chambers. The stirring bar rotates to supply a charge to the developer and to send the developer to a developer carrier. .

[0004] The developer coating amount of the developer carrier is regulated by a blade, and a roller is provided between the developer carrier and the photosensitive drum to keep the distance constant.

[0005] The developer carrier has magnetism consisting of four poles, and further applies a bias consisting of AC and DC to blow the developer onto a photosensitive drum as an image carrier.

A hopper is disposed further above the developer supply port at the end, and the developer in the hopper supplies the developer in response to a developer request signal from a piezoelectric sensor provided in the developing chamber. Replenish.

The replenished developer is sent to the other end on the back side by a screw, and a gutter provided with cutouts for dropping the developer almost uniformly drops the developer into the developing chamber as needed. The structure is such that the developer reaches the developer carrying member through the developing chamber.

In such a developing device, the following problems have occurred due to the supply distribution of the developer.

First, at the initial stage, in a portion where the developer supply distribution is small, sufficient charge is given to the developer by stirring or the like, and a darker image is obtained. Insufficient charge was applied to the image, resulting in a thinner image.

This is because a small amount of the developer is more likely to flow, and the amount of charge applied to the developer varies depending on the degree of the flow even with similar stirring or friction on the sleeve.

Next, as the endurance progresses, the function of making the amount of the developer gradually uniform in the developing chamber has been generated.

Therefore, in a portion where the amount of fresh developer to be replenished is small, that is, in a portion where the supply distribution of the developer is small, the ratio of the fresh developer to the deteriorated developer is lower than the other portions. Increased.

Due to such a phenomenon, in a portion where the amount of the deteriorated developer is increased as compared with the other portions, the density is reduced due to the durability, and a white stripe is generated.

In order to solve such a problem, the distribution of the dropped developer is made as uniform as possible by devising cutting of the distribution member.

[0015]

However, no matter how the distribution distribution of the dropped developer is devised, the fluidity of the developer changes according to the environment. There is no uniform method.

[0016] In addition, a device has been devised to stir and uniform the developer after dropping, but excessive stirring after dropping has promoted deterioration of the developer.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to improve the reliability of uniform release of a developer to an image carrier regardless of environmental changes. An object of the present invention is to provide an excellent developing device and an excellent image forming apparatus.

[0018]

In order to achieve the above object, according to the present invention, there is provided a stirring member for stirring and charging a developer supplied and supplied, and a developer charged by the stirring member. And a developer carrier that discharges the developer to the image carrier after holding the developer. In the developing device, based on the supply distribution that changes depending on the environment of the developer distributed and supplied in the rotation axis direction of the developer carrier, It is characterized in that the degree of surface roughness in the direction of the rotation axis of the agent carrier is changed.

Therefore, by changing the degree of surface roughness in the direction of the rotation axis of the developer carrying member, a developer having a different charge amount for each supply distribution according to the supply distribution that changes depending on the developer environment is used.
It is possible to uniformly and uniformly discharge the image onto the image carrier, and as the developer carrier becomes more durable, the portion of the developer carrier having a higher degree of surface roughness has better developer retention, The deteriorated developer can also be released to the image carrier.

It is preferable to increase the degree of surface roughness of the developer carrier in the portion of the developer carrier that holds the developer in a portion where the amount of the developer supplied is small.

As a result, in a portion where the degree of surface roughness is large, a thin image generally tends to be formed. Therefore, when the surface is roughened in a portion where the supply distribution of the developer is small, sufficient charge is obtained by stirring or the like. The image which is given a darker color can be diluted to obtain a uniform density in the initial image under all circumstances, and the developer discharged to the image carrier can be made uniform.

Further, as the developer carrier becomes more durable,
Since the surface roughness of the developer carrier has a large degree of surface roughness, the surface roughness gradually decreases to an appropriate level, so that the developer holding property is improved, and the amount of the developer gradually increases in the developing chamber. Even if the ratio of fresh developer to deteriorated developer is higher than that of other parts, the deteriorated developer can also be released to the image carrier. It can provide trouble-free images for a long period of time.

It is preferable that the distributed developer is distributed and dropped in the axial direction of the developer carrier.

Thus, the space for holding the replenishing developer can be reduced, and the developer can be distributed by dropping.

It is preferable that the surface of the developer carrying member is formed of a filler-containing resin layer.

Thus, the developer can be easily held.

According to the image forming apparatus of the present invention, the image forming section includes the developing device described above and an image carrier for carrying an electrostatic latent image, and the developer is uniformly discharged to the image carrier. Features.

Thus, since the developing device uniformly discharges the developer to the image carrier, the image density of the image formed on the sheet can be obtained uniformly and satisfactorily.

In addition, when the developer is durable, the portion where the surface roughness of the developer carrier is large deteriorates the developability of the other portion due to the durability, whereas the retention of the developer is improved, and the deteriorated developer is also reduced. It can be released to the image carrier, and the durability is improved.

[0030]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) First, an image forming apparatus according to a first embodiment will be described with reference to FIG.

The image forming apparatus emits a laser beam based on the obtained image information by a laser scanner 1 and irradiates the laser beam on a photosensitive drum 2 as an image carrier constituting an image forming means.

Then, a latent image is formed on the photosensitive drum 2, and the developing device 3 develops the latent image with a developer.

On the other hand, sheets stacked on a sheet feeding device (not shown) are fed while being separated one by one by a feed roller (not shown) and a separation pad (not shown).
The sheet is further conveyed downstream by a conveying means (not shown), and the transfer device 4 transfers the development by the developer formed on the photosensitive drum 2 onto the conveyed sheet.

Then, the sheet on which the unfixed developer image is formed is further conveyed to the conveying belt 5 further downstream.
The developer image is fixed by a fixing device (not shown) and is discharged.

Next, details of the developing device 12 will be described with reference to FIGS.
This will be described with reference to FIGS.

FIG. 2 is a view of the developing device 12 as viewed from above, and FIG. 3 is a view of the gutter 23 as viewed from the direction of the developer carrier 20.

The developing device 3 comprises developing chambers 6 and 7, and stirring rods 8 and 9 as stirring members are disposed in the developing chambers 6 and 7, respectively, and rotate in the direction of the arrow to supply the developer with electric charge. The developer is sent to the carrier 10.

The coating amount of the developer on the developer carrier 10 is regulated by the blade 11.
The distance between them is kept constant by rollers (not shown).

The developer carrier 10 has magnetism of four poles, and applies a bias of AC and DC to blow the developer onto the photosensitive drum 2.

As shown in FIG. 2, a hopper (not shown) is disposed above the developer supply port 12 provided at the end.
The developer in the hopper is a piezoelectric sensor 1 shown in FIG.
The developer is supplied from the developer supply port 12 in accordance with the developer request signal from the developer supply signal 3.

The replenished developer is sent to the other end on the back side by the screw 14.

The gutter 15 located below is provided with cutouts as shown in FIG. 3 so that the developer can be dropped into the developing chambers 6 and 7 as needed.

The gutter 15 in FIG. 3 is provided with cuts 16 to 37 so that the developer can be supplied almost uniformly. The developer dropped from here reaches the developer carrier 10 through the developing chambers 6 and 7.

Next, the falling distribution of the developer falling from the gutter 15 will be described with reference to FIG.

The horizontal axis position in this graph shows the position in the sheet width direction, and K indicates the developer supply port side, and indicates the position on the back side toward A.

The vertical axis indicates the amount of the developer falling in%. This time the drop distribution is 20% 5%, 23 ° C 60
%, And 30% 80% (temperature ° C humidity%) in three environments.

According to FIG. 4, the fall amount on the near side is large at low temperature and low humidity, and the fall amount on the back side is large at high temperature and high humidity.

This phenomenon occurs because the flow distribution of the developer changes according to the environment. In a normal office or the like, there is no change so far, but the developer supply distribution in the central part tends to be small.

As described above, the distribution of the developer supply at the central portion is reduced by any environmental change.
The degree of surface roughness at the center of 0 is roughened.

The surface roughness of the developer carrying member peaks when a darker image is developed at a certain value (depending on the developing carrier). It has the property of becoming an image.

In the present embodiment, a developer carrier having a filler-containing resin layer on the surface is used as the developer carrier of the developing device. The following is the creation method.

The specific surface area by BET is about 1.3 × 10 ⁵
Coupling treatment was carried out on m ² / kg dry silica fine powder with trimethoxysilane to obtain a filler.

As materials for the conductive resin layer 1A, 100 parts by mass of a phenol resin intermediate, 4 parts by mass of carbon black, 36 parts by mass of crystalline graphite, 75 parts by mass of methanol, and 525 parts by mass of isopropyl alcohol were used. .

The above materials were dispersed using a sand mill.

The methanol solution of the phenolic resin intermediate is diluted with a portion of isopropyl alcohol (IPA).
Carbon black and crystalline graphite were added and dispersed by a sand mill using glass beads.

Further, the above treated silica dispersed in the remaining IPA was further added, and the sand mill was further dispersed. Next, the conductive resin layer was applied using this paint.

The sleeve was used by polishing the surface of an aluminum cylindrical tube having an outer diameter of 20 mm and a wall thickness of 0.8 mm so that the cylindrical tube had a run-out of 10 μm or less and a surface roughness of 4 μm or less in Rz.

Stand the work (sleeve) upright,
While rotating at a constant speed, masking was applied to the upper and lower ends, and coating was performed while lowering the spray gun at a constant speed.

The masking width at both ends of the work was set to 3 mm. This was dried and cured at 160 ° C. for 20 minutes in a drying furnace to obtain a conductive resin layer coated sleeve having a uniform film thickness.

The developer carrier produced by the above-described method is a developer carrier having a uniform roughness as a comparative example which is usually used, and is shown in FIG. 5 (a).

Further, the developer carrier according to the present embodiment is obtained by blasting only the central portion of the sleeve made by the above-mentioned method and is shown in FIG. 5B.

The degree of surface roughness of the developer carrier of the comparative example shown in FIG. 5A is Ra = 0.85 μm. The degree of surface roughness at both ends of the developer carrying member according to the present embodiment in FIG. 5B is Ra = 0.85 μm, and Ra at the center is 1.1 μm.

By using such a developer carrier,
In the present embodiment, in a portion where the degree of the surface roughness is rough, a thin image generally tends to be obtained.

As described above, if the surface is roughened in a portion where the supply distribution of the developer is small, a sufficient image is given to the developer by a sufficient charge given by stirring or the like. Developing is best, and the image becomes darker by making it rougher than other parts near the surface roughness of the peak, so that the image can be diluted, and a uniform density can be obtained in all environments, The developer to be blown can be made uniform.

Further, as the developer carrier becomes more durable,
The portion of the developer carrier having a high degree of surface roughness is gradually shaved and smoothed to a level suitable for development.

As a result, the developer transportability is improved, and there is a capability of developing the deteriorated developer as compared with other portions, so that the function of gradually uniforming the amount of the developer in the developing chamber is generated. Even if the ratio of fresh developer to deteriorated developer is higher than that of other parts,
A problem-free image can be provided for a long time.

That is, by partially increasing the roughness of the surface of the developer carrying member, the image at the initial stage of development becomes thinner, and when it is durable, the developing ability is improved and the image becomes darker.
There is a lot of deteriorated developer, and the image does not become too dark, and an image almost equal to other portions can be obtained.

The results of comparing the images with the two types of developer carrying members shown in FIGS. 5A and 5B show that the initial densities are the same, but the development of the comparative example shown in FIG. The agent carrier is 5
In the case of 0000 sheets, an image with a low density at the center was generated, and
Although white streaks occurred at the center of the 0 sheet, a good image was obtained up to 100,000 sheets with the developer carrying member according to the present embodiment shown in FIG. 5B.

The method of supply and distribution is not limited to the method of dropping as in the present embodiment.

(Second Embodiment) The developing device used in the second embodiment is substantially the same as the developing device used in the first embodiment, but the developing device used in the first embodiment is used. A developer having higher fluidity than the developer is used.

The other configuration and operation are the same as those of the first embodiment, and therefore, the same components will be denoted by the same reference characters and description thereof will be omitted.

In the present embodiment, since the developer having a high fluidity is used, if the distribution of the developer is dropped, the developer may be hardened on the back side. Easy configuration.

For this reason, as shown in FIG. 6, the structure of the gutter 15 ′ has a large cut 24 on the near side and a cut 25 on the far side.
Was provided. The drop distribution when the environment changes due to the combination of the gutter 15 'and the developer is as shown in FIG. 7, and the drop distribution on the near side increases.

In this embodiment, as a comparative example shown in FIG. 8A, a developer carrier having a uniform roughness and a second embodiment in which only the back side shown in FIG. Were compared with each other.

The preparation method and surface roughness are the same as those in the first embodiment, and the surface roughness after coating is Ra = 0.85.
Ra = 1.1 μm when blasted with μm.

In this comparison, an initial image in which the developer carrier of the comparative example of FIG. 8A has a density difference of 0.3 at the front and rear sides according to the present embodiment of FIG. 8B. It was 0.1 for the developer carrier.

Further, as a result of the durability test, the developer carrier of the comparative example shown in FIG. 8A produced an image having a low density on the rear side on 20,000 sheets and a white stripe on the rear side on 30,000 sheets. On the other hand, in the case of the developer carrier according to the present embodiment shown in FIG. 8B, good images were obtained up to 50,000 sheets.

As described above, the present invention is not limited to a specific developer, and the surface roughness of each part is set according to the supply distribution of the developer which changes due to environmental changes, so that the developer carrier is formed. Just create it.

[0080]

According to the developing device of the present invention, the surface of the developer carrying member in the direction of the rotation axis is determined based on the supply distribution which varies depending on the environment of the developer distributed and supplied in the direction of the rotation axis of the developer carrying member. By changing the degree of roughness, it is possible to uniformly and uniformly discharge the developer having a different charge amount for each supply distribution according to the supply distribution that changes depending on the developer environment, As the developer carrier becomes more durable, the portion of the developer carrier having a greater degree of surface roughness changes to a roughness suitable for development due to durability, so that the developer retainability is improved,
The deteriorated developer can also be released to the image carrier.

In the portion of the developer carrier that holds the developer in the portion where the supply amount of the developer is small, the degree of the surface roughness is increased.
Generally, the image tends to be lighter, and if the surface is roughened in a portion where the supply distribution of the developer is small, an image in which a sufficient charge is given to the developer by agitation or the like and the image becomes darker can be diluted, and the initial image can be diluted. Therefore, a uniform density can be obtained in all environments, and the developer discharged to the image carrier can be made uniform. In addition, as the developer carrier becomes more durable, the surface roughness of the developer carrier becomes larger. Since the surface roughness gradually decreases to a suitable roughness in the portion where the degree of the roughness is large, the retention of the developer is improved, and the function of gradually uniforming the amount of the developer in the developing chamber occurs. Even if the ratio of fresh developer to deteriorated developer is larger than that of other parts, the deteriorated developer can also be released to the image carrier, and a problem-free image can be obtained for a long time. Can be provided.

The distributed developer is distributed and dropped in the axial direction of the developer carrier, and the developer is distributed by dropping.

Since the surface of the developer carrying member is formed of the filler-containing resin layer, the developer can be easily held.

In the image forming apparatus of the present invention, the developing device described above and an image carrier for carrying an electrostatic latent image are provided in the image forming section, and the developer is uniformly discharged to the image carrier. While the image density of the image formed on the sheet can be obtained uniformly and satisfactorily, and when it is durable, the portion where the surface roughness of the developer carrier is large, whereas the other portions lower the developability, The retention of the developer is improved, and the deteriorated developer can be released to the image carrier, thereby improving the durability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment.

FIG. 2 is a top view showing the developing device according to the first embodiment as viewed from above.

FIG. 3 is a schematic configuration diagram showing a gutter according to the first embodiment.

FIG. 4 is a graph showing a distribution of developer falling from a gutter in the first embodiment.

FIG. 5A is a front view illustrating a developer carrier of a comparative example, and FIG. 5B is a front view illustrating the developer carrier according to the first embodiment.

FIG. 6 is a schematic configuration diagram illustrating a gutter according to a second embodiment.

FIG. 7 is a graph showing a falling distribution of a developer falling from a gutter according to the second embodiment.

FIG. 8A is a front view showing a developer carrier of a comparative example, and FIG. 8B is a front view showing a developer carrier according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser scanner 2 Photosensitive drum 3 Developing device 4 Transfer device 6,7 Developing chamber 8,9 Stirrer bar 10 Developer carrier 11 Blade 12 Developer supply port 13 Piezoelectric sensor 14 Screw 15 Gutter 16-25 Cut out

Claims (5)

[Claims] An agitating member for agitating and charging a developer supplied and distributed; and a developer carrier for temporarily holding the developer charged by the agitating member and then releasing the developer to an image carrier. In the developing device, the degree of surface roughness of the developer carrier in the rotation axis direction is changed based on a supply distribution that varies depending on the environment of the developer distributed and supplied in the rotation axis direction of the developer carrier. Developing device. 2. The developer carrier according to claim 1, wherein a portion of the developer carrier that holds a portion of the developer in which the supply amount of the developer is small increases a degree of surface roughness of the developer carrier. 2. The developing device according to 1. 3. The developing device according to claim 1, wherein the distributed developer is distributed and dropped in an axial direction of the developer carrier. 4. The developing device according to claim 1, wherein the surface of the developer carrier is formed of a filler-containing resin layer. 5. An image forming section comprising: the developing device according to claim 1; and an image carrier for carrying an electrostatic latent image, wherein the developer is uniformly applied to the image carrier. An image forming apparatus that emits light.