JPH0954500A - Two-component developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a controlled distance between a developer carrier and a member for controlling the thickness of a developer layer larger and to form a uniform stable thin later, as for noncontact developing using two-component developer. SOLUTION: As for the two-component developing device for performing noncontact developing, the device is provided with a magnetic member 2a and nonmagnetic member 2b arranged on the downstream side in a developer carrying direction on the developer carrier 1 with reference to the magnetic member 2a as the member 2 for controlling the thickness of the developer layer, and each part coming closest to the developer carrier 1 on the surface of the magnetic member 2a and the nonmagnetic member 2 facing to the developer carrier 1 is arranged on the same plane 3 parallel to the shaft direction of the developer carrier 1. Besides, at least two or more surfaces, or curved surface are formed on the side opposite to the developer carrier 1 of the magnetic member 2a.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer using an electrophotographic technique, and more particularly to a two-component developer comprising a non-magnetic toner and a magnetic carrier. In the type using
The present invention relates to an improvement in a developing device that visualizes an electrostatic latent image on a latent image carrier by a non-contact method.

[0002]

2. Description of the Related Art In recent years, a two-component developing device for visualizing an electrostatic latent image on a latent image carrier by a non-contact method has a latent image carrier and a developer layer formed on the developer carrier. Since they do not come into contact with each other, it is possible to perform high image quality development without causing the fog phenomenon that the developer adheres to the non-image area. Further, in the color developing method using such a two-component developing device, the color toners of different colors are continuously transferred onto the latent image carrier a plurality of times in a non-contact manner, and the color toner images of plural colors are transferred onto the latent image carrier. After being carried, it is possible to transfer them onto the recording paper at once. Therefore, the intermediate transfer drum or belt, which was necessary in the color developing method for transferring the developed image on the latent image carrier to the recording paper each time, is not required, and the downsizing and cost reduction of the apparatus are realized.

A conventional two-component developing device using a non-contact developing method faces a latent image carrier 54 carrying an electrostatic latent image and carries a two-component developer G, as shown in FIG. 9, for example. A developer carrying member 51 and a developer layer thickness regulating member 52, which is arranged close to and facing the developer carrying member 51 and regulates the layer thickness of the developer carried on the developer carrying member 51. The developer carrying member 51 is provided by the developer layer thickness regulating member 52.
A thin layer of a two-component developer is formed on the upper surface, conveyed to a development area facing the latent image carrier 54, and selectively fly toward the electrostatic latent image on the latent image carrier 54 to perform non-contact development. Is to do.

In such a developing device, the tip of the two-component developer layer thinned by the developer layer thickness regulating member 52 does not come into contact with the surface of the latent image carrier 54 when it is conveyed to the developing area. In order to do so, it is necessary to form the developer layer so that the two-component developer layer is thinner and more uniform than the gap between the developer carrier 51 and the latent image carrier 54. For this reason, in many cases, a plate-shaped member (doctor blade) made of, for example, a non-magnetic material is used as the developer layer thickness regulating member 52, and the regulation gap TG between it and the developer carrying member 51 becomes extremely narrow. Need to be fixed accurately. Therefore, since such high accuracy is required, when a deviation occurs in the regulation interval TG between the developer layer thickness regulating member 52 and the developer carrying member 51, a complicated correction work is required. Further, since the regulation interval TG is extremely narrow, agglomerates of toner particles and foreign matter such as paper fibers are clogged,
As a result, there is a problem that white spots (streaks) occur in the image.

[0005]

Therefore, in order to increase the regulation distance between the developer layer thickness regulating member and the developer carrying member, the tip of the developer layer thickness regulating member is made of a magnetic material, or a magnetic material is used. Several proposals have been made in which a plate made of is bonded to a conventional nonmagnetic plate-shaped layer thickness regulating member.

In Japanese Patent Laid-Open No. 59-29872, a developer layer thickness regulating member is composed of a plate-shaped member made of a magnetic material. In the method according to this type, the magnet disposed inside the developer carrying member magnetizes the plate-shaped magnetic member, so that the magnetic field between the magnetic member and the developer carrying member is strengthened, and along the magnetic field. So-called developer spikes in which the developer is continuous occur. At this time, since the filling rate of the developer in the spiked state becomes relatively coarse, the regulation interval for obtaining the developer layer thickness of the amount necessary for development can be increased.

However, the spike of the developer breaks away from the magnetic field when the magnetic adhesive force between the carriers weakens to form a developer layer, so that the cutting position between the carriers varies and the layer is uniform. Are difficult to form. In particular, if there is unevenness in the magnetization of the internal magnets, the variation in the cutting position between the carriers becomes more prominent, and it becomes difficult to form a more uniform layer. Furthermore, the magnetic carrier used in the two-component developer is
Since the magnetic susceptibility is large, hard ears are formed, and the mutual repulsion between the ears also influences each other, resulting in large gaps between the ears and a rough texture of the developer layer. Especially,
In the method of developing in a thin layer such as non-contact development, such unevenness (uneven layer thickness of the developer, rough texture of the developer layer) remarkably appears in a low density portion such as a halftone and developability. It becomes a big problem in terms of. Therefore, in order to prevent such unevenness, a non-magnetic member is provided on the downstream side of the magnetic member in the developer transport direction, and the non-magnetic member presses the upper surface of the developer layer to form a uniform thickness. In addition, some proposals have been made for smooth smoothing.

JP-B-63-45594, JP-A-62-
The developer layer thickness regulating member described in JP-A-138860 and JP-A-2-73383 is a magnetic member and a non-magnetic member disposed on the downstream side of the magnetic member in the developer carrying direction on the developer carrier. It is composed of a magnetic member, and is arranged with a step so that the distance between the magnetic member and the surface of the developer carrier is larger than the distance between the non-magnetic member and the surface of the developer carrier. In the method of this type, the non-magnetic member has an effect of blocking (shielding) the magnetic force on the non-magnetic member side out of the magnetic force directed from the internal magnet to the magnetic member, and only the magnetic force from one side works intensively. , Realizes a uniform and uniform spike. Furthermore, the magnetic field between the internal magnet of the developer carrying member and the magnetic member causes the developer to stand up, and as soon as the layer thickness is regulated by the magnetic member, the developer is cut by the non-magnetic member arranged in steps with respect to the magnetic member. Since they are aligned, even if the developer surface varies due to the regulation of the layer thickness by the magnetic member, the upper layer portion can be smoothed with a uniform layer thickness.

However, the magnetic field received by the magnetic member is
It greatly depends on the distance from the internal magnet, and as the distance increases, the magnetization of the magnetic member weakens.Therefore, in the type in which the step between the magnetic member and the non-magnetic member is increased in this way, the step is increased when the regulation interval is widened. As a result, the magnetic field received by the magnetic member becomes weaker, and it becomes impossible to achieve both the effect of widening the regulation interval and the strength of the magnetic field. Furthermore, in recent years, there has been a demand for an era of miniaturization of the apparatus, and since the diameter of the internal magnet becomes smaller as the diameter of the developer carrying member becomes smaller, the magnitude of the magnetic force that can be magnetized is also limited, and a sufficiently wide regulation interval is provided. There is a problem that can not be set.

Therefore, an object of the present invention is to solve the conventional problems described above in the non-contact development using a two-component developer, and to set the regulation interval between the developer carrying member and the developer layer thickness regulating member. It is an object of the present invention to provide a developing device including a developer layer thickness regulating member that can be set wider and can form a uniform and stable thin layer.

[0011]

That is, as shown in FIG. 1, a two-component developing device according to the present invention faces a latent image carrier 4 on which an electrostatic latent image is carried, and a two-component developer G. And a developer carrier 1 on which the developer is carried, and a developer layer thickness regulation in which the layer thickness of the developer carried on the developer carrier 1 is arranged in close proximity so as to face the developer carrier 1. And a member 2 for forming a two-component developer in a thin layer on the developer carrying member 1 by the developer layer thickness regulating member 2 and transporting the two-component developer to a developing area facing the latent image carrying member 4 to form a latent image carrying member. In the two-component developing device for selectively flying toward the electrostatic latent image on the developing unit 4 to perform non-contact development, the developer layer thickness regulating member 2 includes a magnetic member 2a and a developer for the magnetic member 2a. A non-magnetic member 2b disposed on the carrier 1 on the downstream side in the developer transport direction,
The portions of the magnetic member 2a and the non-magnetic member 2b facing the developer carrier 1 that are closest to the developer carrier 1 are arranged on the same plane 3 parallel to the axial direction of the developer carrier 1. It is a feature.

In such a technical means, if the developer carrying member 1 can carry and convey the developer, a magnet member in which a plurality of magnetic poles are arranged is fixedly installed in a rotatable developing sleeve. Alternatively, conversely, a magnet member may be rotatably provided in the fixed developing sleeve. However,
Since the internal magnet generates a magnetic field between itself and the magnetic member 2a, it is necessary to satisfy appropriate magnetic characteristics.

The developing method may be appropriately selected as long as it uses the two-component developer G in the non-contact state, but from the viewpoint of easily transferring the developer toner, the transfer electric field is used. It is preferable to electrostatically transfer by applying a forming bias.

Further, among the constituents of the developer layer thickness regulating member 2, the magnetic member 2a may be appropriately selected as long as it has suitable rigidity such as magnetic stainless steel and the magnetic characteristics. On the other hand, the non-magnetic member 2b may be appropriately selected as long as it is a material that is not easily affected by external environmental changes such as temperature and humidity, and has rigidity that does not cause twisting or warping. Particularly, in order to obtain a smooth and uniform surface, which is resistant to changes in the external environment, it is desirable to use stainless steel and polish the tip facing the developer carrying member into a sword shape.

From the viewpoint of further widening the regulation interval between the developer carrying member 1 and the developer layer thickness regulating member 2, at least two magnetic members 2a are provided on the side facing the developer carrying member 1. It is preferable to use one having a face.

Further, in order to more effectively widen the regulation interval between the developer carrying member 1 and the developer layer thickness regulating member 2, the magnetic member 2a has a curved surface on the side facing the developer carrying member 1. Preferably.

[0017]

The operation of the device invention shown in FIG. 1 will be described with reference to the above technical means. The developer carrying member 1 adsorbs the two-component developer G supplied in the vicinity on the surface of the developer carrying member 1 by the magnetic force of the magnet arranged inside the developer carrying member 1 and then continuously conveys it in the direction of the arrow in the figure. are doing. Since the carrier is magnetic particles, the two-component developer G composed of the carrier and the toner is arranged along the magnetic lines of force of the internal magnet of the developer carrier 1 to form a brush-shaped developer layer (magnetic brush). Meanwhile, the developer carrier 1 conveys the developer to the vicinity of the developer layer thickness regulating member 2.

On the other hand, in the developer layer thickness regulating portion, since the magnetic member 2a is disposed close to the developer carrying member 1, the magnetic member 2a is magnetized by the internal magnet, and the internal magnet changes to the magnetic member 2a. A bundle of magnetic lines of force that extends from is generated. The magnetic brushes conveyed there are continuous along the lines of magnetic force, and rise up from the developer carrying member 1 toward the magnetic member 2a. At this time, the non-magnetic member 2b has an effect of blocking (shielding) the magnetic force on the non-magnetic member 2b side, out of the magnetic force directed from the internal magnet to the magnetic member 2a, and the magnetic force concentrates on the magnetic member 2a. , Uniform and uniform ears are realized. Due to the spikes, the densely arranged magnetic brushes become coarse, so that the filling rate of the developer decreases.

As soon as the developer is conveyed, the spiked magnetic brush has its upper layer portion cut by the non-magnetic member 2b to make the spike length uniform. Further, when the magnetic brush of the magnetic member 2a is moved away from the range of influence of the magnetic field due to the developer transport, the magnetic brush in the spiked state is attracted to the surface of the developer carrier 1 by the magnetic force of the internal magnet, and the two-component developer A thin layer is formed. In this way, the magnetic member 2a and the developer carrier 1
It is possible to form a thin layer of a predetermined developer with a uniform thickness and smoothly while maintaining a large regulation interval with the.

By the way, when a plate-shaped member having a rectangular cross section is used as the magnetic member 2a, the lines of magnetic force from the internal magnet 2a are concentrated on the edge portion having an acute angle, and the number of spikes of the developer extending to this portion increases. . This concentration of magnetic force lines is caused by the magnetic member 2
The sharper the angle of the edge of a, the more likely it is to occur. Therefore, if the edge of the surface of the magnetic member 2a facing the developer carrying member 1 is shaved so as to have at least two surfaces, the concentration of magnetic force lines on a part of the edge of the magnetic member 2a can be avoided.
Even lines of magnetic force are formed over the entire developer regulating portion. Therefore, the spikes of the developer can be made more even and rough over the entire developer control section, so that the developer filling rate (density) in the developer control section becomes smaller and the predetermined developer transport amount is obtained accordingly. The regulation interval for this is further widened. Also,
If the surface of the magnetic member 2a facing the developer carrying member 1 is a gently curved surface, local concentration of magnetic force lines can be more reliably avoided.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A developing device according to the present invention will be specifically described below with reference to an embodiment shown in the accompanying drawings. First Embodiment FIG. 2 shows a color image forming apparatus incorporating an embodiment of a developing device to which the present invention is applied. In the figure, the color image forming apparatus includes a charger 7 for uniformly pre-charging the photosensitive drum 6 around the photosensitive drum 6 carrying the electrostatic latent image along the rotation direction thereof, and an image information. And an exposure device 8 for forming an electrostatic latent image according to the above, and first to fourth developing devices for yellow, magenta, cyan, and black for visualizing the electrostatic latent image with a two-component developer. 5 (specifically 5a to 5d), a pre-transfer charger 9 for aligning the charging characteristics of the toner image on the photosensitive drum 6 before transfer, and a transfer charging for transferring the toner image on the photosensitive drum 6 to the recording paper K. Vessel 10
A peeling charger 11 for peeling the transferred recording paper K from the photosensitive drum 6, a cleaning device 12 for removing the residual toner on the photosensitive drum 6, and a static eliminator 13 for removing the residual charge on the photosensitive drum 6. The respective electrophotographic recording devices are sequentially arranged.

In the image forming process of such a color image forming apparatus, for example, the surface of the photosensitive drum 6 is uniformly charged by the charger 7 to 650 V, and then the exposure device 8 irradiates light based on the image signal. Thus, for example, the process of forming an electrostatic latent image having a potential of −200 V in the image area and visualizing it by the developing device 5 is repeated a plurality of times to form a multicolor toner image on the photosensitive drum 6, and before transfer. After the charging characteristics of the toner images are made uniform by the charging device 9, the toner images are transferred to the recording paper K by the transfer charging device 10, and the recording paper K after transfer is separated from the photosensitive drum 6 by the peeling charging device 11. Is to do.

The first to fourth developing devices 5 have exactly the same structure except for the color of the toner to be housed therein. Of these, for example, the developing device 5c will be described in detail with reference to FIG. The developing device 5c has a developing opening 23 on the photosensitive drum 6 side.
Housing 2 in which the two-component developer G is accommodated
4, a developing roll 21 disposed adjacent to the photosensitive drum 6 facing the developing opening 23 of the housing 24, and disposed adjacent to the opposite side of the developing roll 21 from the photosensitive drum 6. A developer layer thickness regulating member 22 that regulates the amount of developer attached on the developing roll 21 is provided.

Further, the developing roll 21 is provided with a developing sleeve 21b rotatable in the direction of the arrow in the figure, and a magnet 21a in which a plurality of magnetic poles fixedly arranged are arranged. The developing roll 21 includes a developer supply member 25 that supplies the developer to the developing roll 21 while rotating in the direction of the arrow in the figure. Further, the developer supply member 25 stirs the developer and also supplies the developer. 25, a developer stirring member 26 for supplying the developer is provided.

Further, the developing sleeve 21b and the photosensitive drum 6
The gap between and is set to a distance that allows the toner to fly sufficiently. This gap can be set as appropriate and is preferably about 0.3 to 0.9 mm. 0.3
If the width is smaller than mm, it is affected by the fluctuation of the gap due to the shake of the developing sleeve 21b and the photosensitive drum 6, etc., and it becomes difficult to perform stable development with a uniform density. On the other hand, when the width is wider than 0.9 mm, the flying effect of the toner due to the alternating electric field is lowered, a sufficient density cannot be obtained, and a sharp image cannot be obtained due to the edge effect. From the above points, in the first embodiment, it is set to 0.4 mm.

Furthermore, these two developer stirring members 26
Is rotationally driven so as to convey the developer in mutually opposite directions, agitates the developer and circulates it in the housing 24. The two-component developer G including the non-magnetic toner and the magnetic carrier is sufficiently stirred by the developer stirring member 26 and is conveyed to the vicinity of the developer supply member 25. In the process of stirring and carrying, the distribution of the non-magnetic toner in the developer is maintained uniform, and the non-magnetic toner is charged by the friction between the non-magnetic toner and the magnetic carrier.

The stirred developer is supplied to the developer supply member 25.
After being supplied to the developing roll 21 by the developing sleeve 2
1b is magnetically attracted to the surface of the developer 1b to form a magnetic brush, and the developer layer thickness regulating member 2 is rotated as the developing sleeve 21b rotates.
It is conveyed to the vicinity of 2 and regulated to an appropriate layer thickness by the developer layer thickness regulating member 22. This restricting operation will be described later. It should be noted that the developer layer thickness regulating member 22 includes the housing 24.
The developer layer thickness regulating member 22 and the developing roll 21 are held at a constant regulating distance (trimmer gap TG).

Next, regarding the developer layer thickness regulating member 22,
This will be described in detail with reference to FIG. Developer layer thickness regulating member 22
Is composed of a magnetic member 22a and a non-magnetic member 22b arranged downstream of the magnetic member 22a in the rotational direction of the developing sleeve 21b. The non-magnetic member 22a and the developing roll 21 of the non-magnetic member 22b. The portion of the opposing surface closest to the developing roll 21 is arranged on the same plane A parallel to the axial direction of the developing roll 21.

Further, the tip of the non-magnetic member 22b is polished in a sword shape so that twisting or warping does not occur, and the processed side is arranged so as to come to the downstream side in the rotation direction of the developing sleeve 21b. Set up. On the other hand, the unprocessed surface is set at 90 ° with respect to the contact surface of the surface of the developing sleeve 21 which is the closest to the surface. Therefore, FIG.
In the developer layer thickness regulating member 22 and the developing sleeve 21,
The closest point to the non-magnetic member 22a and the magnetic member 2 is
It is a point B which is the boundary surface with 2b and is closest to the developing sleeve 21.

The position of the closest contact point B is the magnetic pole S1 of the developer regulating portion and the magnetic pole N1 in the rotating direction of the developing sleeve 21.
The magnetic force in the radial direction of the developing sleeve 21 on the S1 side is larger than the magnetic force in the tangential direction. In this region, the trimmer gap TG can be maximized, and the influence of the displacement of the mounting position of the developer layer thickness regulating member 22 on the developing roll 21 on the developer layer thickness can be reduced.

In the first embodiment, the magnetic member 2
Although magnetic stainless steel (SUS430 or the like) is used for 2a and non-magnetic stainless steel (SUS304 or the like) is used for magnetic member 22b, it is not particularly limited as long as it satisfies the respective magnetic characteristics and has rigidity. Absent.

Next, the regulating operation of the developer layer thickness regulating member 22 in this embodiment will be described. First, the two-component developer G is attracted to the surface of the developing sleeve 21b by the magnetic force of the fixed magnet 21a inside the developing roller 21, and at the same time forms a magnetic brush. Continuous developer layer thickness regulating member 2
It is transported to the vicinity of 2.

On the other hand, in the developer layer thickness regulating portion, since the magnetic member 22a is disposed close to the surface of the developing sleeve 21b, the magnetic member 22a is magnetized by the internal magnet 21a, and the magnetic member 22a moves from the internal magnet 21a. A bundle of magnetic field lines extending to is generated. The magnetic brushes conveyed there are continuous along the lines of magnetic force, and the developer layer is in a spiked state from the developing sleeve 21b toward the magnetic member 22a.

At this time, the non-magnetic member 22b is the inner magnet 2
It plays a role of blocking (shielding) the magnetic force on the non-magnetic member 22b side from the magnetic force directed from 1a to the magnetic member 22a,
Since only the magnetic force from one side acts intensively, a uniform and uniform spike is realized. Further, the spikes of the magnetic brush change the arrangement of the magnetic brushes from a dense state to a coarse state, and reduce the filling rate of the developer in the layer thickness regulating portion.

Thereafter, as the developing sleeve 21b rotates, the non-magnetic member 22b cuts the spike-upper upper layer portion to make the spike-up length uniform. The magnetic brush thus uniformly cut away is affected by the magnetic force of the internal magnet 21a as it moves away from the range of influence of the magnetic field of the magnetic member 22a as the developing sleeve 21b rotates. It is sucked onto the surface of the roll 21 to form a thin layer of the two-component developer. As described above, the magnetic member 2
While maintaining a large trimmer gap between 2a and the developing roll 21, a predetermined thin layer of developer can be formed with a uniform thickness and smoothly.

In evaluating the performance of the developer layer thickness regulating member according to the first embodiment, a comparative example consisting only of conventional non-magnetic members was examined. At this time, in the present embodiment, the filling rate of the developer in the layer thickness regulating portion is small, whereas the line of magnetic force acts between the developer layer thickness regulating member of the comparative example and the developing sleeve 21b. Therefore, since the filling rate of the developer in the layer thickness regulating portion becomes large,
The same developer amount, that is, the trimmer gap required to obtain the developer layer can be set wider in the present embodiment than in the comparative example. In fact, as a developer, the magnetic carrier has an average particle size of 40 μm and a saturation magnetic force of 40 μm.
A non-magnetic toner having an average particle diameter of 10 μm at emu / g is used, and the developing roller 21 has a diameter of 18 mm.
When the peripheral speed is 256 mm / sec, the trimming magnetic force is 60 mT, and the magnetic member 22a has a thickness D = 1 mm, the developer layer thickness 20 in the developing region is 20.
The trimmer gap TG required to obtain 0 μm and a developer transport amount of 110 g / m ² is 0.5 mm, compared to 0.2 mm in the comparative example, which is significantly wider in the present embodiment than in the comparative example. It was confirmed that it can be set.

Further, FIG. 5 is based on the first embodiment.
6 is a graph showing a value of a trimmer gap for obtaining a predetermined developer layer thickness when the distance between the tip surface of the magnetic member and the tip surface of the non-magnetic member is changed. According to this,
When the magnetic member was configured to be retracted from the tip of the non-magnetic member, there was a leveling effect, but the trimmer gap became significantly narrower as the influence of the magnetic field decreased. On the contrary, when the magnetic member is projected from the non-magnetic member, the trimmer gap is widened, but the smoothing effect of the non-magnetic member is lost, and unevenness occurs for the same reason as in the case of the restricting member made of only the magnetic member. . From this, it was confirmed that the positional relationship between the magnetic member and the non-magnetic member that can set the trimmer gap to the maximum while uniformly leveling the developer layer is when the front end surfaces are aligned. .

Second Embodiment FIG. 6 shows a second embodiment. In the developing device 5c of the first embodiment, a developing roll is used instead of the magnetic member 22a of the developer layer thickness regulating member 22. The magnetic member 32a having two surfaces on the side facing 21 is used.

In the second embodiment, the ratio of the width of the A surface to the thickness D of the magnetic member 32a in FIG. 6 is set within a certain range, and the N distance is set so that the indicated distance L becomes a certain value or less. Set the developing sleeve 21b to the magnetic member 32.
Since no line of magnetic force is generated in a, the effect of widening the trimmer gap cannot be obtained.

Although these appropriate values differ depending on the magnetic force and magnetic pattern in the magnet 21a, for example, the trimming magnetic force S1 is 30 mT to 100 mT, and the magnetic force N1 of the next pole downstream from the S1 in the rotation direction of the developing sleeve 21b. Thirty
When the developing roll 21 of mT to 100 mT is used, the thickness D of the magnetic member 32a is in the range of 0.5 mm to 3.0 mm, and the A surface is in the range of 20% to 80% of the thickness D. Therefore, the distance L from the lowest point B on the N surface is preferably 0.5 mm or less.

According to the developing device 5c to which the second embodiment is applied, the edge of the surface of the magnetic member 32a facing the developing sleeve 21b is shaved so as to have two surfaces. Concentration of the magnetic force lines is avoided, and uniform magnetic force lines are formed over the entire developer regulating portion. Therefore, since the spikes of the developer in the developer regulating section become more uniformly rough over the entire developer regulating section, the developer filling rate becomes smaller, and the predetermined developer conveyance amount is obtained accordingly. The trimmer gap of is further expanded. Especially,
In the present embodiment, of the magnetic force from the internal magnet 21a toward the magnetic member 22a, the magnetic force that wraps around to the non-magnetic member 22b side is blocked (shielded), so that the magnetic force acts intensively. It becomes more effective to grind the edge on the side opposite to the magnetic member 22b to form two obtuse angles.

In evaluating the performance of the developer layer thickness regulating member 32 according to the second embodiment, comparison was made with the comparative example made of a non-magnetic member and the first embodiment. That is, as a developer, the average particle size of the magnetic carrier is 40 μm, the average particle size of the non-magnetic toner is 10 μm with a saturation magnetic force of 40 emu / g.
The developing roller 21 has a diameter of φ18.
mm, peripheral speed 256 mm / sec, trimming magnetic force 60 m
A magnetic member 32a having a thickness of D = 1 m is used.
m, the edge on the opposite side of the non-magnetic member 22b is 0.3 at 45 °
In the case of using the one scraped by mm, the trimmer gap TG required to obtain a developer layer thickness of 200 μm in the developing region and a developer transport amount of 110 g / m ² is 0.2 in the comparative example.
However, it was confirmed that the size of the embodiment can be set significantly wider than that of the comparative example. In addition, even if compared with the first embodiment, 0.
It has been improved from 5 mm to 0.55 mm, and it was confirmed that the point of cutting the edge contributes to widening the trimmer gap TG.

Further, the graph of FIG. 7 shows the results of the investigation of the change in the developer transport amount with respect to the change in the trimmer gap in the case of the second embodiment and the case of the comparative example. According to this, it was confirmed that in the second embodiment, the change in the developer transport amount with respect to the change in the trimmer gap is significantly smaller than that in the comparative example. This indicates that it is unlikely to be affected by the change in the trimmer gap due to the touch of the developing roll and the like, and a stable developer transport amount can be secured as compared with the comparative example. Therefore, by using such a developer layer thickness regulating member, it is possible to prevent density unevenness due to the supply of the developer amount and to ensure good image quality.

Third Embodiment FIG. 8 shows a developer layer thickness regulating member 4 used in the third embodiment.
2 shows that the magnetic layer 42a having a curved surface is used in place of the magnetic member 32a in the developer layer thickness regulating member 32 of the second embodiment, and an effect equal to or higher than that of the second embodiment is obtained. Is what you get.

[0045]

As described above, according to the developer layer thickness regulating member of the two-component developing device of the present invention, the parts of the magnetic member and the non-magnetic member, which are the constituent elements, which are the closest to the developer carrying member. Since they are arranged on the same plane parallel to the axial direction of the developer carrier, the developer regulation thickness can be set significantly wider than that of the conventional developer layer thickness regulating member, and paper fibers and developer aggregates can be set. Problems such as image defects such as white streaks caused by clogging of foreign matter such as are solved.

Further, the influence on the change of the regulation interval due to the contact of the developer carrying member is extremely small, and the stable developer conveyance amount can be secured. However, it is possible to obtain a high quality image without unevenness.

Further, with the recent demand for downsizing of the apparatus, the diameter of the developer carrying member also tends to be reduced. However, when the developer carrying member has a small diameter, the upper limit of the magnetic force that can be magnetized becomes smaller, so that the trimmer is smaller. The gap also tends to narrow. Therefore,
By using the developer layer thickness regulating member which is a constituent element of the present invention, it is possible to easily meet such a demand.

Further, in the present invention, when at least two or more surfaces are formed on the side of the magnetic member facing the developer carrying member or a curved surface is formed, magnetic force concentration on the edge is prevented. Therefore, the spikes of the developer can be made more uniform and rough over the entire developer regulation portion. For this reason, it is possible to reduce the developer filling rate (density) of the developer regulation portion, and the regulation interval for obtaining the predetermined developer conveyance amount can be further widened accordingly.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a two-component developing device according to the present invention.

FIG. 2 is a color image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a developing device according to the first embodiment of the present invention.

FIG. 4 is a developer layer regulating member according to the first embodiment of the present invention.

FIG. 5 is a relationship between a distance between a magnetic member and a non-magnetic member and a regulation interval.

FIG. 6 is a developer layer restriction member according to the second embodiment of the present invention.

FIG. 7 is a relationship between the regulation interval and the developer transport amount.

FIG. 8 is a developer layer regulating member according to the third embodiment of the present invention.

FIG. 9 is a relationship between a distance between a magnetic member and a non-magnetic member and a regulation interval.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Developer carrying member, 2 ... Developer layer thickness regulating member, 2b ... Non-magnetic member, 2a ... Magnetic member, 3 ... Same surface, 4 ... Latent image carrying member, G ... Two-component developer

Claims (3)

[Claims] 1. A latent image carrier (4) carrying an electrostatic latent image.
And a developer carrying member (1) on which the two-component developer (G) is carried, and a developer carrying member (1) which is disposed in close proximity to the developer carrying member (1). A developer layer thickness regulating member (2) for regulating the layer thickness of the carried developer,
The two-component developer is formed in a thin layer on the developer carrying member (1) by the developer layer thickness regulating member (2), and is conveyed to the developing area facing the latent image carrying member (4), thereby carrying out the latent image carrying member. (4) In a two-component developing device for selectively flying toward an electrostatic latent image on the surface of the developer for non-contact development, the developer layer thickness regulating member (2) is a magnetic member (2a).
And a developer carrier (1) for the magnetic member (2a).
And a non-magnetic member (2b) disposed on the downstream side in the developer conveying direction, and the magnetic member (2a) and the non-magnetic member (2b) are opposed to the developer carrier (1). A two-component developing device characterized in that a portion closest to the developer carrying member (1) is arranged on the same plane (3) parallel to the axial direction of the developer carrying member (1). 2. The two-component developing device according to claim 1, wherein the magnetic member (2a) has at least two or more surfaces on the side facing the developer carrying member (1). . 3. The two-component developing device according to claim 1, wherein the magnetic member (2a) has a curved surface on a side facing the developer carrying member (1). [0001]