JPH0220118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device that develops a latent image using a non-magnetic developer.

Conventionally, various devices have been proposed and put into practical use as dry one-component developing devices. However, in any of the development methods, it is extremely difficult to form a thin layer of dry one-component developer, and for this reason, a developing device has been constructed by forming a relatively thick layer. However, as improvements in the clarity, resolution, etc. of developed images are currently being sought, it is essential to develop a method for forming a thin layer of a dry one-component developer and an apparatus therefor.

As a conventionally known method for forming a thin layer of a dry type one-component developer, Japanese Patent Application Laid-Open No. 43037/1983 has been proposed and has been put to practical use. However, this concerned the formation of a thin layer of magnetic developer. Magnetic developers must have a magnetic material added to the toner to make it magnetic, which can lead to poor fixing properties when heat fixing the developer transferred to transfer paper, and magnetic material in the developer itself. Since the image is internally added, there are problems such as poor color reproduction during color reproduction.

For this reason, as a method for forming a thin layer of non-magnetic developer,
Proposed methods include using a cylindrical brush made of soft beaver hair to apply the developer, and applying the developer to a developing roller with a surface made of fibers such as velvet using a doctor blade. has been done. However, if an elastic blade is used as a doctor blade for the above fiber brush,
Although it is possible to regulate the amount of developer, it is not applied uniformly, and the fiber brush on the developing roller is simply rubbed, and no triboelectric charge is imparted to the developer present between the fibers of the brush. Therefore, there was a problem that ghosts and the like were likely to occur. Furthermore, unlike magnetic developers, non-magnetic developers have the disadvantage that they cannot be transported by magnetic force.

The present invention eliminates the problems of the conventional method described above, and improves the movement of the developer and magnetic particles by processing the surface of the developer holding member into irregularities, thereby distributing non-magnetic developer uniformly onto the surface of the developer holding member. It is an object of the present invention to provide a novel developing device that forms a thin layer and applies sufficient triboelectric charging.

A developing device of the present invention that achieves the above object includes a container that stores non-magnetic developer and magnetic particles, a developer holding member that rotatably conveys the non-magnetic developer to a latent image carrier, and a non-magnetic developer of the container. a regulating member disposed on the magnetic developer supply outlet side and arranged with a gap formed on the surface of the holding member; and a regulating member disposed on the opposite side of the regulating member across the holding member and arranged at the developer outlet of the container. and a magnetic field generating means having a magnetic pole forming a magnetic brush made of magnetic particles on the upstream side of the regulating member located on the side, and forming a thin layer of non-magnetic developer on the developer holding member. This is a developing device in which the surface of a developer holding member is sandblasted to form an uneven surface. In the present invention, when performing sandblasting with irregularly shaped particles, pitch P = 5 to 50μ and surface roughness R _Z = 1 to 5μ; when performing sandblasting with regular particles, pitch P = 10 to 70μ. , the surface roughness R _Z =2 to 10μ.

As the latent image carrier of the present invention, a drum-shaped or belt-shaped member having a photoreceptor and an insulating layer is used. Further, as a moving developer holding member,
It is possible to use a sleeve made of non-magnetic metal such as aluminum, copper, stainless steel, brass, etc., a synthetic resin material, or an endless belt made of resin or metal. In addition, as a regulating member, magnetic materials such as iron, aluminum,
A blade plate or wall made of non-magnetic material such as copper or resin may be used.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a sectional view of a developing device for explaining the developing principle of the present invention. In the figure, reference numeral 1 denotes an electrophotographic photosensitive drum as a latent image carrier, which holds a latent image formed by a latent image forming means (not shown) and rotates in the direction of arrow a to pass through a developing position shown in the drawing. For this photosensitive drum 1, a non-magnetic sleeve 2, which is a developer holding member that holds developer, is attached.
are opposed to each other with a predetermined gap maintained between them, and this sleeve 2 rotates in the direction of arrow b. This sleeve 2
A non-magnetic container 3 made of aluminum or the like is located above the container 3 for storing a mixture of a non-magnetic developer 4 and magnetic particles 5, and downstream of this container 3 in the rotational direction of the sleeve,
A magnetic blade 6, which is a regulating member, is screwed.

On the other hand, the sleeve 2 for this magnetic blade 6
On the opposite side, a magnet 7 is provided as a magnetic field generating means. The mounting position of this magnet is determined by the relationship between the position of the magnetic pole and the magnetic blade 6, and in reality, the magnetic pole is provided slightly upstream of the position of the magnetic blade 6 in the direction of movement of the sleeve. By doing this,
The action of the formed magnetic field effectively prevents the magnetic particles from flowing out and uniformly coats the developer.

In the above configuration, the magnetic particles 5 in the container 3 are
A magnetic brush 8 is formed by the magnetic field generated between the S pole of the magnet 7 and the magnetic blade 6. As the sleeve 2 rotates, the magnetic brush 8
The magnetic particles and the non-magnetic developer are stirred and mixed while maintaining the magnetic particles and the non-magnetic developer. In this state, on the magnetic blade side of the container 3, due to the presence of the blade 6, the mixture of developer and magnetic particles is prevented from moving by the blade, rises, and circulates in the direction of arrow c.

Non-magnetic developer is triboelectrically charged by mixing with magnetic particles. The charged developer is transferred to the magnetic blade 6
A magnetic brush 8 formed near the sleeve 2 applies a thin, uniform coating onto the surface of the sleeve 2 by reflection force, and reaches a position facing the photoreceptor drum.

By the way, the magnetic particles 5 constituting the magnetic brush 8
The magnetic particles do not flow onto the sleeve 2 by setting the binding force due to the magnetic field of the magnet 7 to be larger than the conveying force caused by the electrostatic adhesion force and frictional force between the sleeve and the magnetic particles. If there is non-magnetic developer within the area of the magnetic brush 8, the ratio of the magnetic particles of the magnetic brush 8 to this developer remains approximately constant as the sleeve 2 rotates. Thereby, even if the developer on the sleeve is consumed during development, the developer is automatically supplied to the area of the magnetic brush 8. Therefore,
A constant amount of developer can always be supplied and coated onto the sleeve 2.

In addition, in the above explanation of the principle, a magnetic blade is used as the regulating member, but the non-magnetic blade or the wall of non-magnetic material such as resin or aluminum that constitutes the container can be
It can also be used as this regulating member. However, in this case, to prevent the outflow of magnetic particles,
It is necessary to make the gap between the sleeve and the regulating member even smaller than when using a magnetic blade. Further, when a magnetic blade is used, it is preferable because a magnetic brush can be stably formed at the developer outlet by the magnetic field between the blade and the magnetic pole, and the magnetic particles can be restrained and circulated.

FIG. 2 shows an embodiment of the invention. In the figure,
The same members as those in FIG. 1 are given the same reference numerals. 1 is a photosensitive drum, 2 is a developing sleeve for holding a developer, 6 is a magnetic blade, 4 is a non-magnetic toner, and 5 is a magnetic carrier, which together form a two-component developer. 7 _-1 to 7 _-4 are magnets arranged inside the sleeve. 3 is a developing container; 9 is a bias power source for applying a bias voltage to the developing sleeve 2; the developing container 3 is provided with a stirring blade 11 that rotates around a shaft 10; In the developing container, the carrier 5 and the non-magnetic toner 4 are weakly coupled by electrostatic force and attracted to the magnets 7 _-3 and 7 _-2 .

The role of the magnetic carrier is to disperse the non-magnetic toner and transport the non-magnetic toner while being attracted to the sleeve.
The developer used is the toner concentration used in normal two-component magnetic brush development (for example, 2 to 12 wt%).
A two-component developer containing 30 to 70 wt% toner is used, which is several times the amount of toner.

The two-component developer attracted by the magnet is conveyed to the magnetic blade 6 by rotation of the sleeve.
During this conveyance process, the two-component developer consisting of the non-magnetic toner 4 and the carrier 5 is attracted to the surface of the sleeve 2 by magnetic force and rubs against the sleeve, so the non-magnetic toner 4 also flows onto the surface of the developing sleeve 2. It is attracted by electrostatic force. In the magnetic blade 6, carrier particles are retained in the magnetic blade 6 due to the magnetic field in the gap e formed by the magnet _7-1 and the magnetic blade 6, forming a brush-like shape, and are scraped off from the surface of the sleeve 2.

On the other hand, the non-magnetic toner 4 adhering to the surface of the sleeve 2 passes through the blade 6 without being affected by this magnetic field, and a thin layer of non-magnetic toner 4 is formed on the surface of the sleeve 2. The developing sleeve 2 is supplied to the adjacent developing section. The cut magnetic pole _7-1 , which prevents the particles of the carrier 5 from leaking out from the blade 6, is tilted toward the developer container 3 by 5 to 15 degrees (θ in the figure). In this way, all magnetic poles 3 _-1 ~
By limiting _3-4 to the developer container, leakage of magnetic flux from the magnetic blade 6 to the developer container is prevented, and since the magnetic flux is limited only to the developer container 3, the carrier 5 moves from the blade 6 to the developer container. It will almost never be taken outside.

To explain this state in more detail, the non-magnetic toner 4
The developer containing the developer is attracted to the sleeve 2 and conveyed to the magnetic blade 6 section. Since the magnetic pole 7 _-1 inside the sleeve is attached at a slightly inclined position with respect to the magnetic blade 6, the magnetic flux there is weakened. Therefore, the force with which the developer is restrained by the sleeve is small, and the developer is pushed by other developers adsorbed on the upstream side of the sleeve in the direction of movement and moves away from the sleeve along the magnetic blade. Further, as shown in the figure, the developer moves greatly within the developer container in the direction shown by arrow c, and is circulated and agitated. In addition, near the tip of the magnetic blade, as the sleeve rotates, small loop rotation and vibration movements appear to occur, increasing the chance of contact between the non-magnetic toner and the sleeve, creating a sufficient triboelectric charge on the non-magnetic toner. . At the same time, the large amount of toner contained in the carrier is separated from the developer by the rotational and vibrating motion and adheres to the sleeve surface, resulting in uniform toner coating. At this time, the carrier particles each act as a small induced magnet, exert a binding force on each other, and are restrained within the developer container 3.
Since the magnetic field in this state is as shown in FIG. 3, almost no magnetic flux is generated on the downstream side of the magnetic blade 6. Therefore, the carrier 5 will not be pulled by the conveying force of the sleeve and go out between the magnetic blade and the sleeve.

The gap d between the photosensitive drum 1 and the developing sleeve 2 is
In the absence of an external electric field, the thin layer of toner on the sleeve is sufficiently wide so that it does not come into contact with the surface of the photosensitive drum 1. During development, by setting the developing sleeve roller to a predetermined potential using the bias power supply 9, desired image quality can be obtained. At this time, as a bias, JP-A-55-18656-9
Jumping development can be performed by using the alternating voltage described in the publication.

In this embodiment, the non-magnetic toner is charged by friction with the carrier and sleeve surfaces. Preferably, the surface of the carrier is coated with an oxide film or an insulating treatment such as a resin that is electrostatically almost the same unit as the toner, so that the amount of triboelectricity imparted from the carrier to the toner is reduced, and the triboelectricity necessary for development is applied only from the sleeve surface. By doing so, deterioration of the carrier can be prevented and toner can be easily applied to the sleeve surface. Since the carrier is not directly involved in development and only plays the role of transporting and stirring the non-magnetic toner to the sleeve surface, it is only necessary to replenish the non-magnetic toner. The magnet 7 fixed within the sleeve is arranged so that a magnetic field exists only on the side of the developer container 3, and the magnetic flux on the sleeve surface needs to be 400 to 600 G.

In the developing device configured as described above, the non-magnetic toner is attracted to the sleeve surface, and the amount thereof is regulated by the magnetic blade, so that it is necessary to form a coating in a constant layer. The sleeve surface is required to transport the developer to the magnetic blade section, and the blade section circulates or vibrates the developer up and down to separate the toner from the developer. Furthermore, it is necessary to specify the surface properties of the sleeve so that the carrier adsorbed on the sleeve surface is not drawn out of the magnetic blade.

In the present invention, in order to satisfy these conditions, the sleeve surface is roughened by sandblasting.

If the sleeve surface is not roughened at all or if the surface roughness is extremely small, a toner layer of a desired thickness cannot be formed on the sleeve under normal circumstances, resulting in a low image density. In addition, in a low humidity environment, the thin toner layer on the sleeve has areas where the tribocharge is locally high, and the toner layer becomes thicker, causing so-called unevenness. Therefore, toner also adheres to non-image areas on the copy, causing image stains.

On the other hand, if the surface roughness is too large, the electric field due to the developing bias will be concentrated on the convex portions, resulting in a so-called rough copy image with uneven solid black portions. In addition, the toner layer also becomes quite thick, which tends to cause toner scattering and fogging. Furthermore, when used for a long period of time, a phenomenon occurs in which toner is fused to the recessed portions.

Therefore, in order to form a thin toner layer on the sleeve, it is preferable to control the surface roughness within a certain range. Although it is impossible to uniquely describe the surface properties of the sleeve required in the present invention,
As an example, the roughened surface shown in Figure 4 was measured using a microsurface roughness meter (sold by Taylor Hobson, Kosaka Institute, etc.).
When measured, a waveform as shown in FIG. 5 is obtained, and the surface properties can be controlled.

Here, the surface roughness is JIS 10 point average roughness (RZ)
This is based on "JIS B 0601". In other words, as shown in Figure 5, a straight line parallel to the average line of the section of the cross-sectional curve by the standard length is drawn from the highest point.
The distance between the two lines is expressed in micrometers (μm), one passing through the top of the third mountain, and the other passing through the bottom of the third valley from the deepest point, and the reference length was set as 0.25 mm. Also, the pitch should be set against the convex part or the concave parts on both sides.
A height of 0.1μ or more was counted as one peak, and the number of peaks within a standard length of 0.25 mm was calculated as follows.

250μ/Number of peaks included in 250μ Specifically, the condition of the uneven rough surface in one embodiment of the present invention was determined by sandblasting using irregularly shaped particles, and the pitch P of the unevenness (Fig. 5, large depressions) and recess,
or the average distance between convex parts) is 5 to 50μ,
It is preferable that various irregularities having a surface roughness R _Z of 1 to 5 μm as defined above exist randomly.

The irregularly shaped particles here refer to those obtained by crushing hard materials such as carbon, silicon carbide, alumina, etc. and classifying only abrasive grains of a specific size, for example, 20μ to 70μ. The shape refers to angular and pointed particles, which give the sleeve surface an uneven shape with sharp edges. The surface of the sleeve roughened with irregularly shaped particles has extremely high frictional resistance, which can promote toner transport and carrier movement.

When the sleeve surface was roughened using such amorphous abrasive grains, the surface roughness was 0.1μ or more and the toner transportability was good. However, the effect of promoting movement on the carrier was small, and only a thin coating was obtained because less toner was separated. So, when we made the surface roughness more than 1μ,
It was possible to obtain sufficient toner coating.
Furthermore, when the blade was processed to a roughness of 5μ or more, the force that carried the carrier became too strong, and the result was that the carrier, especially the small-diameter particles, were drawn out to the outside of the magnetic blade, as if the carrier were being held together.

When the pitch of the unevenness was 5 μm or less, the roughening effect was not exhibited, the conveyance performance of the carrier deteriorated, and the triboelectric charge applied to the toner became uneven, resulting in uneven toner coating. Also, the uneven pitch
It has been found that when the thickness exceeds 50μ, the rate of change in unevenness=surface roughness _RZ /pitch P becomes small, and the effect of promoting movement on the developer becomes small. Therefore, in the present invention, the sleeve surface is roughened using under-shaped particles so that the surface roughness R _Z is within the range of 1 to 5 μm and the pitch is within the range of P = 5 to 50 μm.

An experiment was conducted with the configuration of the developing device shown in FIG. 2 set as follows.

Developing sleeve 2: Outer diameter 32φ, sleeve rotation:
Same circumferential speed as the drum (300 mm/S), magnet 7: 400 Gauss on the surface of the developing sleeve, gap e between the developing sleeve 2 and the magnetic blade 6 = 0.5 mm, inclination angle θ between the magnetic pole 7 _-1 and the magnetic blade 6 = 10°, gap d between developing sleeve 2 and photoreceptor drum 1 = 0.3 mm, developer is black toner (well-known non-magnetic resin toner)
It is a two-component developer having a carrier (magnetic material) and a carrier (magnetic material).

The frequency is applied to the developing sleeve 2 by the bias power supply 9.
An AC bias voltage of 150 V was applied at 600 Hz, peak-to-peak value was 1.5 KV, and the center value had the same polarity as the latent image.

(Example 1) Morundum No. 600 manufactured by Showa Denko K.K. was used as blasting abrasive grains for surface processing of a developing sleeve (material: stainless steel SUS304). This is an alumina-based abrasive grain with a particle size of approximately 25μ. At this time, the spray nozzle diameter is 7φ, the distance is 150m/m, and the air pressure is 4.
Kg/cm ² , sandblasting for 2 minutes, sleeve surface roughness R _Z = 1μ, pitch P
Values of =5 to 20μ were obtained.

When the latent image surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good and no uneven coating occurred. When continuous copying was performed in this state, no uneven development was observed in the image, and a good image could be maintained.

(Example 2) Green Density No. 400 manufactured by Showa Denko K.K. was used as blasting abrasive grains for surface processing of a developing sleeve (made of aluminum). This is a silicon carbide abrasive grain with a particle size of approximately 35μ. At this time, the spray nozzle diameter is 7φ, the distance is 250m/m, and the air pressure is 4.
Kg/cm ² , sandblasting for 4 minutes, sleeve surface roughness R _Z = 2μ, pitch P
Values of =15-30μ were obtained.

When the latent image surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good and no uneven coating occurred. When continuous copying was performed in this state, no uneven development was observed in the image, and a good image could be maintained.

(Example 3) Morundum No. 200 manufactured by Showa Denko K.K. was used as blasting abrasive grains for surface processing of a developing sleeve (material: stainless steel SUS304). This is an alumina-based abrasive grain with a particle size of approximately 50μ. At this time, the spray nozzle diameter is 7φ, the distance is 150m/m, and the air pressure is 4Kg/
cm ² and sandblasting for 2 minutes.
Sleeve surface roughness R _Z = 5μ, pitch P = 20
A value of ~50μ was obtained.

When the latent image surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good and no uneven coating occurred. When continuous copying was performed in this state, no uneven development was observed in the image, and a good image could be maintained.

It is of course possible to use other grain sizes and types of abrasive grains in addition to those described in this example by adjusting the diameter of the blasting nozzle, the distance between the nozzle and the sleeve, the blowing pressure, etc., and depending on the sleeve surface material. It is. In the developing device configuration examined in this experiment, particularly good results were obtained when irregularly shaped abrasive grains of No. 200 to No. 600 were used.

Abrasive grains used to roughen the sleeve surface are generally classified into two types. One of them is the irregularly shaped particles mentioned above, which are angular particles called abrasives. Others are called regular particles,
These particles are nearly spherical in shape. When the sleeve surface is processed with irregularly shaped particles, it is possible to process the surface into an uneven surface with edges. sleeve surface
When roughened to R _Z =1 to 5μ and applied to the development method described above, a stable toner coating is formed and exhibits good initial characteristics.

However, it has been found that in the developer containing the magnetic carrier used in the present invention, as the developer is used repeatedly, the uneven edge tip portions are worn out and the toner conveying ability is reduced. Approximately 3,000 copies when using aluminum as the sleeve material, approximately 30,000 copies when using stainless steel (SUS304)
It was found that the image density decreased after printing.

On the other hand, if the sleeve is roughened with regular particles,
The sleeve has a rounded, uneven surface that is resistant to wear and has an extremely long life.

Therefore, in the second embodiment of the present invention, the sleeve surface is processed using regular shaped particles in the developing method. The term "shaped particles" as used herein refers to particles of a specific size such as glass or iron balls, for example, abrasive grains of 50 to 70 microns that are classified.
The particles are approximately spherical in shape and have no corners, giving the sleeve surface an uneven appearance.

When the sleeve was roughened using regular abrasive grains, toner transportability was good when the surface roughness was 1μ or more.
However, the effect of promoting movement on the carrier was small, the amount of toner decomposed was small, and only a thin coating was obtained. Therefore, the roughness
When the thickness was set to 2μ or more, sufficient toner coating could be obtained. Furthermore, when machining to a roughness of 10μ or more, the force that conveys the carrier becomes too strong, resulting in the magnetic blade pulling out the carrier, especially small-diameter particles, to the outside as if the carrier was being held in place. .

When the pitch of the unevenness is 10 μm or less, the roughening effect is not exhibited, the conveyance performance of the carrier is deteriorated, and the triboelectric charge applied to the toner becomes uneven, resulting in uneven toner coating. Also, the uneven pitch
It has been found that when the thickness exceeds 70μ, the rate of change in unevenness=surface roughness _RZ /pitch P becomes small, and the effect of promoting movement on the developer becomes small. Therefore, in the present invention, regular shaped particles are used to improve surface roughness.
The sleeve surface is roughened to a range of R _Z =2 to 10μ and pitch P of 10 to 70μ.

An experiment was conducted with the configuration of the developing device shown in FIG. 2 set as follows.

Developing sleeve 2: Outer diameter 32φ, sleeve rotation:
Same circumferential speed as the drum (300 mm/S), magnet 7: 400 Gauss on the surface of the developing sleeve, gap e between the developing sleeve 2 and the magnetic blade 6 = 0.5 mm, inclination angle θ between the magnetic pole 7 _-1 and the magnetic blade 6 = 10 degrees, the gap d between the developing sleeve 2 and the photosensitive drum 1 is 0.3 mm, and the developer is a two-component developer containing a black toner (a well-known non-magnetic resin toner) and a carrier (a magnetic material).

The frequency is applied to the developing sleeve 2 by the bias power supply 9.
An AC bias voltage of 150 V was applied at 600 Hz, peak-to-peak value was 1.5 KV, and the center value had the same polarity as the latent image.

(Example 4) As blasting abrasive grains for surface processing of a developing sleeve (material: stainless steel SUS304), Fuji Manufacturing Co., Ltd.
I used FGB number 300. This is a nearly spherical particle with a diameter of approx.
They are 50μ glass beads. At this time, sandblasting was performed under the conditions of spray nozzle diameter 7φ, distance 150m/m, air pressure 3Kg/cm ² for 2 minutes, and sleeve surface roughness values of R _Z = 2μ and pitch P = 10 to 30μ were obtained. .

When the latent image surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good and no uneven coating occurred. When continuous copying was performed in this state, no uneven development was observed in the image, and a good image could be maintained.

(Example 5) FGB300 manufactured by Fuji Seisakusho was used as blasting abrasive grains for surface processing of the developing sleeve (material is aluminum)
I used the number. This is a glass bead with approximately spherical abrasive grains of approximately 50μ. At this time, the spray nozzle diameter
Sandblasting was performed under the conditions of 7φ, distance 250 m/m, air pressure 3 Kg/cm ² for 2 minutes, and sleeve surface roughness values of R _Z =4 μ and pitch p = 20 to 40 μ were obtained.

When the latent image surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good and no uneven coating occurred. When continuous copying was performed in this state, no uneven development was observed in the image, and a good image could be maintained.

(Example 6) Used by Fuji Seisakusho as blasting abrasive grains for surface processing of developing sleeve (material: stainless steel SUS304)
I used FGB number 200. This is a nearly spherical particle with a diameter of approx.
They are 50μ glass beads. At this time, the spray nozzle diameter is 7φ, the distance is 150m/m, and the air pressure is 4Kg/cm ² .
Sandblasting was performed under the conditions of 1 minute, and the sleeve surface roughness was R _Z = 10 μ, pitch P = 30 to 70 μ.
obtained the value of

When the latent image surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good and no uneven coating occurred. When continuous copying was performed in this state, no uneven development was observed in the images.
I was able to maintain a good image.

When sleeves surface-treated using the methods described in Examples 4 to 6 above were used, image quality could be maintained up to approximately 20,000 copies in the case of an aluminum sleeve and approximately 150,000 copies in the case of a stainless steel (SUS304) sleeve. did it.

In addition to those described in this example, other particle sizes and types of abrasive grains can be used by adjusting the blasting nozzle diameter, nozzle-sleeve distance, blowing pressure, etc., or by changing the sleeve surface material. Of course. In the developing device configuration examined in this experiment, particularly good results were obtained when abrasive grains of No. 200 to No. 300 were used.

As described in detail above, the present invention provides a development method in which magnetic particles and non-magnetic developer are stored in a developer container, the magnetic particles are circulated within the container, and only the non-magnetic developer is applied to a developer holding member. In the device, the surface of the developer holding member is roughened by sandblasting, which promotes the movement of the nonmagnetic developer and magnetic particles and forms a uniform thin layer of nonmagnetic developer on the surface of the developer holding member. It became possible to do so. In addition, since we use a non-magnetic developer that does not contain magnetic materials,
It has the advantage of being able to perform color development.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a developing device for explaining the principle of the present invention, Fig. 2 is a cross-sectional view of an embodiment of the developing device according to the present invention, and Fig. 3 is an explanation showing the state of magnetic flux on the sleeve surface due to the magnet. 4 are explanatory diagrams showing the state of roughness of the sleeve surface, and FIG. 5 is a waveform diagram of the sleeve surface measured with a micro surface roughness meter. In the figure, 2...Developing sleeve, 3...Developing container, 4...Nonmagnetic toner, 5...Carrier, 6
. . . magnetic blade, 7 . . . magnet, 9 . . . bias power supply.

Claims (1)

[Scope of Claims] 1. A container for storing a non-magnetic developer and magnetic particles, and a container for transporting the non-magnetic developer to a latent image carrier by rotation. A rough surface with a pitch P = 5 to 50μ and a surface roughness Rz = 1 to 5μ, or a rough surface with an uneven pitch P = 10 to 70μ and a surface roughness R _Z = 2 to 10μ by sandblasting with regular particles. a developer holding member, located on the non-magnetic developer supply outlet side of the container,
A regulating member is arranged with a gap formed on the surface of the holding member, and a magnetic material is arranged on the opposite side of the regulating member through the holding member, and is located upstream of the regulating member on the developer outlet side of the container. and a magnetic field generating means having a fixed magnetic pole that forms a magnetic brush of particles, and the regulating member and the magnetic pole restrain the magnetic brush of the magnetic particles so that they do not flow out of the container, and the magnetic brush is not placed on the developer holding member. A developing device that forms a thin layer of magnetic developer. 2. The developing device according to claim 1, wherein a voltage having an alternating current component is applied to the developer holding member.