JPS6296980A - Developer thin layer forming device - Google Patents

Abstract

PURPOSE:To obtain good images without photographic fog by agitating a developer to be stuck to the surface of a developer carrier and forming a thin layer of the developer on the surface of the developer carrier reaching a developing part. CONSTITUTION:Magnetic particles 7 carried by rotation of a sleeve 3 are raised by the front end part of an elastic body blade 6 and are dropped near a magnetic pole 5 by the gravity and the magnetic force and are circulated in the direction of an arrow (c) repeatedly, and magnetic particles 7 are oscillated considerably near the magnetic pole 5. A developer 8 is agitated in a vessel 2 and is charged frictionally by rubbing against magnetic particles 7. When passing the contacting part between the elastic body blade 6 and the sleeve 3, the developer 8 is charged frictionally furthermore by rubbing against the surface of the sleeve 3 and the elastic body blade 6. The frictionally charged developer 8 passes the contacting part and is formed as a developer thin layer on the sleeve 3 and is carried to the developing part facing a photosensitive body 1 on the sleeve 3. Thus, good images are obtained stably.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Summary of the Invention The present invention provides a developer thin layer forming device that can be used in a developing device that develops an electrostatic latent image using a non-magnetic developer.

Various types of dry-component developing devices have been proposed and put into practical use. However, in any of the development methods, it is extremely difficult to form a thin layer of dry-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 component developer and an apparatus therefor.

Conventionally known dry method - Exploiting thin layer of component developer -4-
Sujitsuji sill 7-) Casting rib ζJ-J 7-oh has been proposed and has been put into practical use. However, this concerned the formation of a thin layer of magnetic developer. Magnetic developers must have a magnetic substance added to them to have magnetism, and this is due to poor fixing properties when thermally fixing the developed image transferred to transfer paper, and because the developer itself contains magnetic substances (magnetic substances do not contain magnetic substances). Since the color (usually black) is added internally, 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, there are two methods: using a cylindrical brush made of soft bristles like beaver's hair, and applying the developer to the brush. A method of coating the developing roller with a doctor blade or the like has been proposed. However, when an elastic blade is used as a doctor blade for the above-mentioned fiber brush, it is possible to regulate the amount of developer, but uniform application is not achieved, and the fibers of the brush are simply rubbed by the fiber brush on the developing roller. Since no triboelectric charge is imparted to the developer present in between, there is a problem in that fogging and the like are likely to occur.

In addition, in this type of development method, since the developer comes into contact with the image carrier surface regardless of the presence or absence of an electrostatic image, developer adhesion occurs even in non-image areas, that is, areas where there is no electrostatic charge. Developers that are not sufficiently charged tend to adhere to non-image areas, resulting in fogging and resulting in poor images.

Prior and First 11 The present applicant uses a non-magnetic developer and magnetic particles as a developing device that is completely different from the conventional method described above, provides a magnetic particle restraining member opposite to a developer holding member, and uses a magnetic particle restraining member to prevent movement of the surface of the holding member. Regarding the direction, a magnetic brush of magnetic particles is formed by the magnetic force of the magnetic field generating means upstream of the magnetic particle restraining member, the magnetic brush is restrained by the magnetic particle restraining member, and a thin layer of non-magnetic developer is applied to the developer holding member. We have already proposed an apparatus for forming a thin developer layer.

The present invention further improves this developer thin layer forming device, ensures good binding properties and stability of magnetic particles with a simple configuration, and stably forms a thin developer layer on the surface of a developer holding member over a long period of time. An object of the present invention is to provide a developer thin layer forming device that can form a good copy image.

A further object of the present invention is to provide a developer thin layer forming apparatus that has a simple configuration and is capable of producing good copy images without blurring.

1. According to the present invention, there is provided a developer supply container having an opening and containing a developer and a small amount of magnetic particles, and a non-container provided in the opening and capable of moving endlessly inside and outside the container. A magnetic cylindrical developer holding member, a magnetic field generating means provided inside the developer holding member, and a magnetic pole of the magnetic field generating means that contacts the developer holding member at a downstream position in the rotational direction of the developer holding member. a blade having an end urged to contact the developer holding member, the blade being inclined downstream from the end in the rotational direction and elastically abutting on the developer holding member; has only one magnetic pole in the quadrant where the blade end is located among four quadrants formed by a vertical line passing through the center of the developer carrier and a horizontal line; There is provided a developer thin layer forming device that forms a thin layer of developer on the developer holding member downstream of the blade in the member movement direction, so that good magnetic particle restraint can be achieved with a simple configuration. Since the developer can be sufficiently charged while ensuring the image quality, it is possible to provide a good image without background fog.

Support 1 FIG. 1 is a partial sectional view of a developer thin layer forming apparatus according to an embodiment of the present invention.

In this embodiment, the developer thin layer forming device develops an electrostatic latent image on a photoreceptor 1 as a latent image carrier rotating in the direction of arrow a. As the photoreceptor 1, for example, a so-called xerographic photoreceptor on which an electrostatic latent image is formed by the Carlson process, N described in Japanese Patent Publication No. 42-23910,
A photoreceptor having an insulating layer on the surface with an electrostatic latent image formed by the P process, an insulator having a latent image formed by the electrostatic recording method,
It is an insulator to which an electrostatic latent image is transferred by a transfer method, or a member to which an electrostatic latent image (or potential latent image) or magnetic latent image is formed and retained by any other appropriate method.

The developer thin layer forming device includes a developer supply container 2, a sleeve 3 as a developer holding member, a magnet 4 as a magnetic field generating means, and an elastic blade 6.

The container 2 has an opening extending in the longitudinal direction (direction perpendicular to the plane of the paper) of the developer thin layer forming device, and a developing sleeve 3 as a developer holding member is provided in the opening. Made of non-magnetic material such as aluminum. sleeve 3
In the figure, it is installed horizontally in the opening with its right half-circumferential surface extending into the container 2 and its left half-circumferential surface exposed outside the container so that it can freely rotate on a bearing, and is driven to rotate in the direction of the arrow. . The developer holding member 3 is not limited to the above-mentioned cylindrical body (sleeve), but may be in the form of an endless belt that is driven once, or may be a conductive rubber roller. The magnet 4 facing or contacting the surface of the photoreceptor 1 with a small gap is provided in the developing sleeve 3, and in this embodiment, it is a fixed permanent magnet, and the sleeve 3 is rotationally driven. It maintains a fixed position and posture even when the robot is moved, and generates a fixed magnetic field. This magnet 4 has a magnetic pole 5 (N pole). As the magnet 4, an electric magnet may be provided instead of a permanent magnet.

The elastic blade 6 is provided in contact with the outer surface of the sleeve 3. The contact point is located downstream of the position of the magnetic pole 5 of the magnet 4 in the direction of rotation of the sleeve 3, and the elastic blade 6 is provided inclined toward the downstream side (that is, opposed to the direction of rotation of the sleeve).

The magnet 4 has only one magnetic pole located closer to the elastic blade 6 than the vertical line passing through the center of the sleeve 2.

The magnetic pole is upstream of the contact point.

Further, a small amount of magnetic particles 7 and developer 8 are placed inside the container 2, and the magnetic particles 7 are restrained on the surface of the container 2 by the action of the magnetic field of the magnet 4, forming a magnetic brush. There is. Here, the term "very small amount" refers to a very small amount that exists only in the vicinity of the regulating blade with respect to the surface of the developer carrier at the opening of the developer supply container, and more specifically, a minute amount that exists in the vicinity of the blade and does not cause any development in the vicinity. The amount is such that the surface of the agent carrier is hardly covered with magnetic particles and is exposed to the developer. More specifically, this release is such that 90% or more of the surface of the developer carrier is released from the magnetic particles in the area where the magnetic particles exist near the blade portion. According to an embodiment of the present invention, a small amount of magnetic particles are contained in the developer container near the tip of the blade that is brought into elastic contact with the surface of the developer carrier, and a small amount of magnetic particles are circulated near the tip of the blade. The developer adhering to the surface of the developer carrier is stirred, and a thin layer of developer is formed on the surface of the developer carrier leading to the developing section.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

When the sleeve 3 rotates in the direction of the arrow A, the magnetic particles 7 are conveyed in the direction of rotation of the sleeve 3 while being restrained by the magnetic field formed by the magnet 4. However, the magnetic particles 7 are prevented from being conveyed by the ends of the elastic blades 6 and released outside the container 2, and fall toward the vicinity of the magnetic poles 5 due to gravity and magnetic force. At this time, the magnetic particles 7 circulate near the end face of the elastic blade 6 and vibrate violently near the magnetic pole 5 due to the restraining force of the magnetic pole 5 and the rotational force (conveying force) of the sleeve 3. On the other hand, the developer 8 containing the rIi particles 7 is
It enters the contact area between the elastic blade 6 and the sleeve 3 and is carried out of the container on the surface of the sleeve 3.

As the magnetic particles 7 circulate and vibrate, the developer 8 is stirred inside the container 2 and at the same time rubs against the magnetic particles 7, thereby being triboelectrically charged. Furthermore, when the developer 8 passes through the contact portion between the elastic blade 6 and the sleeve 3, it is rubbed against the surface of the sleeve 3 by the elastic blade 6, and is further subjected to frictional electrification. In this way, the developer 8 can receive sufficient triboelectric charging. As a result, image density can be ensured in the developed image, and background fog can be further reduced.

The developer 8 that has been sufficiently triboelectrically charged in this way passes through the contact portion, is formed as a thin layer of developer on the sleeve 3, and is carried on the sleeve 3 to a developing section facing the photoreceptor 1. In the developing section, some of the developer is consumed by the developing operation, and other developer is recovered from the lower part of the sleeve 2 as the sleeve 3 rotates. A sealing member 9 is provided in this recovery portion to allow the developer that has not been consumed during development to pass into the container 2, and to prevent the magnetic particles 7 and developer 8 in the container 2 from leaking out from the bottom of the container 2. 0 The collected developer on the sleeve 3 is magnetic particles 7.
The developer is once scraped off by the circulation and vibration of the developer, and then stirred and mixed by the magnetic particles 7, and then applied again as a thin layer of developer onto the surface of the sleeve 3. In this way, the developer that has not been consumed during development is once scraped off from the surface of the sleeve 3, so regardless of the variation in the amount of developer remaining on the surface of the sleeve 3 after development, the developer that has not passed through the contact area A thin layer of developer of uniform thickness is formed on the subsequent surface. Also,
Since the developer is once scraped off in this manner, the developer on the sleeve 3 is replaced, thereby preventing excessive charging of the developer, that is, charge-up.

An example of a developing method is the method described in Japanese Patent Publication No. 58-32375, in which a minute gap is provided between the photoreceptor 1 and the developing sleeve 2, and an alternating current with a superimposed direct current is applied between them. A method may be used in which a thin layer of developer is transferred onto an electrostatic latent image on a photoreceptor, but a contact development method may also be used.

Next, the elastic blade 6 will be explained in detail.

FIG. 2 is a sectional view of the vicinity of the elastic blade of the developer thin layer forming device when the present invention is not used.

In this figure, the elastic blade 6 is tilted upstream with respect to the rotation direction of the sleeve 3 (forward direction with respect to the sleeve rotation direction). In this configuration, when the sleeve 3 rotates, the magnetic particles 7 are The developer 8 in the upper part of the container 2 is clogged near the tip of the container 2, and the magnetic particles 7 are not circulated and vibrated. Therefore, sufficient triboelectric charging is not achieved. It has been found that because the developer cannot be taken in, unevenness tends to occur in the thin developer layer. In addition, the magnetic particles 7 enter the contact portion between the elastic blade 6 and the sleeve 3, and as a result, the contact pressure between them becomes non-uniform, and streak-like unevenness occurs in the formed developer thin layer. Furthermore, in this case, the magnetic particles 7 are partially pressed against the sleeve 3, causing damage to the surface of the sleeve 3.

FIG. 3 is a cross-sectional view of the vicinity of the elastic blade of the developer thin layer forming device when the present invention is used. In this configuration, the magnetic particles 7 transported by the rotation of the sleeve 3 are lifted upward by the tip of the elastic blade 6, and are moved near the magnetic pole 5 by gravity and magnetic force. It was confirmed that the magnetic particles 7 could be repeatedly circulated in the direction of arrow C, and that the magnetic particles 7 vibrated significantly near the magnetic pole 5. Since the amount of magnetic particles is very small, this vibration is violent due to the conveying force of the sleeve 3, the reversing force of the blade 6, the pullback force of the magnetic force, and the pullback force of gravity.

Due to the circulation and vibration action of the magnetic particles 7.

The developer is sufficiently triboelectrically charged and is stably supplied onto the surface of the sleeve 3 from the top of the container 2. Further, due to the above-mentioned action, residual developer on the sleeve 3 can be scraped off, so that in combination with the effect of using the elastic blade described above, a thin layer of developer with a uniform thickness can be stably formed.

Next, as the material of the elastic blade 6, for example, JIS
Rubber with a hardness of 40 to 80'', preferably 50 to 70'', is suitable for stable formation of a thin layer of developer.The thickness of the elastic blade 6 is such that the magnetic particles 7 ride on the back surface of the elastic blade 6. According to the inventor's experiments and considerations, it is preferable to have a certain degree of thickness to prevent this.
It is 1 mm or more, preferably 2.0 mm or more.

FIG. 4 is a cross-sectional view showing the elastic blade mounting configuration.
Since the elastic blade 6 is pressed against and in contact with the surface of the sleeve 3, it is deformed as shown. This urges the end of the blade 6 to come into contact with the sleeve 3. Note that the term "blade end" as used herein refers to the tip of the blade, the vicinity including the tip, or the vicinity of the tip not including the tip. The blade 6 is inclined downstream in the rotational direction of the sleeve from the end. The zero dotted line indicates the state of the elastic blade 6 assuming that the sleeve 3 does not exist. The straight line m is a vertical line passing through the center of the sleeve 3. n is a straight line passing through the contact portion Q of the elastic blade 6 and the sleeve 3 and the center of the sleeve 3, and the straight line is a straight line passing through the center of the sleeve 3 and the center of the magnetic pole 5. The 0 plane T, where the angle between the straight line m and the line &In is X, and the angle between the straight line n and the straight line is y, is the bottom surface of the elastic blade 6 when the elastic blade 6 is in contact with the sleeve 3 and is not deformed. The 0 point P is the cross section of the line of intersection between the plane T and the surface of the sleeve 3, the angle θ is the angle between the tangent of the sleeve 3 passing through point P and the plane T, and the distance d is the point where the plane T is inside the sleeve 3. This is the length of the approach. Although the straight line m passes through the point P here, this is not necessarily necessary.

The angle θ is set between 0° and 40°, preferably between 29° and 20°, in order to prevent problems such as the elastic blade 6 bending back due to frictional force when the sleeve 3 rotates.
The range is 0'''.

Further, the penetration amount d of the first elastic blade 6 is preferably 0.5 to 2 mm, and it is preferable that the edge portion of the tip of the elastic blade 6 is in contact with the sleeve 3. It has been found that if the edge of the tip of the blade 6 is separated from the surface of the sleeve 3, the magnetic particles 7 will enter this gap, impairing the uniformity of contact pressure and potentially damaging the surface of the sleeve 3. It is from.

Furthermore, it is preferable that the angles X and y satisfy the following conditions.

X≧O y＞.

x+y<90'' Regarding the angle Due to the relationship of zero gravity, it was found that the angle X
The preferred range of is 5°<x<40''.

Regarding the angle y, it has been found that when y≦00, the magnetic particles 7 stick to the vicinity of the tip of the elastic blade 6, preventing circulation and vibration, which is not preferable. In addition, 30
It has been confirmed that particularly good circulation and vibration are achieved when ''<7<60'', which is preferable.

Regarding the angle It has been found that the circulating and vibrating magnetic particles 7 are no longer present, which is undesirable.

From the above considerations, more preferable ranges are as follows.

5"　<x<40" 30°<y<so.

x+y<90'' In this range, sufficient circulation and vibration of the magnetic particles 7 can be obtained, and therefore stable developer application can be obtained.

The surface of the sleeve 3 is preferably provided with minute irregularities rather than a mirror surface from the viewpoint of circulation and vibration of the magnetic particles 7.

As the magnetic particles 7, iron powder, ferrite powder, etc. can be used. Furthermore, it is more preferable that these are coated with a resin in accordance with the charging polarity of the developer 8.
The magnetic particles 7 may have a particle size of 50 to 200 ILm. It was confirmed that if it is below 50 pm, the fluidity of the magnetic particles 7 is poor, sufficient circulation and vibration cannot be obtained, the amount of developer 8 taken in is reduced, and a stable thin layer of developer 8 is not formed. Furthermore, in the case of a particle size of 200 pm or more, although the developer 8 is sufficiently supplied, triboelectric charging is not sufficient, which is not preferable.
80-150 gm is particularly preferred in order to obtain sufficient circulation and vibration of the magnetic particles 7.

FIG. 5 is a sectional view of a specific example of a developing device using the developer thin layer forming device according to the present invention. In this figure, the same reference numerals as in FIG. 1 are given to corresponding members and means, so detailed explanations thereof will be omitted.

The sleeve 3 used was an aluminum sleeve with a diameter of 20 mm whose surface was subjected to amorphous sandblasting with Alundum abrasive grains, and the magnet 4 used had a peak magnetic flux density of 800 Gauss and a half width of 60 @. There was 0
The elastic blade 6 is made of silicone rubber (rubber hardness JI
S60", thickness 2mm).These mounting positions are θ=10", d=1.0mm, x=15@, y=5
It was set as 00.

The magnetic particles have a particle size of 100 to 80 pm (150/20
0 mesh) iron particles (maximum magnetization = 190 emu/g
) coated with acrylic and fluorine resin, and the developer is a toner with an average particle size of 13 ILm consisting of 100 parts of a copolymer of styrene/acrylic resin and styrene-butadiene resin and 5 parts of perylene-based pigment. It is said that a red toner with 1.0% colloidal silica added externally to the powder was used.
A uniform coating layer of 0.4 m was obtained. When the amount of charge on this layer was measured using the blow-off method, the amount of charge was +12 g c
/g, which is a sufficient value.

The developing method used here is
A voltage is applied between the electrophotographic photoreceptor and the sleeve 3 by a bias power source.

The bias power source may be alternating current or direct current, but preferably one in which direct current is superimposed on alternating current.The developing method is not limited to this, and development may be performed by bringing a thin layer of developer into contact with the photoreceptor 1.

This developer thin layer forming device is manufactured by Canon Co., Ltd.
20 built into a copying machine, frequency 160 as a bias power supply
0Hz, AC voltage with peak and peak voltage of 1300v,
Using a superimposed DC current of -300V, the surface potential of the latent image l on the photoconductor was set to -540V in the dark area and -220V in the bright area, and the surface potential of the latent image l on the photoconductor was set to -540V in the dark area and -220V in the bright area. When development was carried out with the spacing set at 250 gm, a good red image with a reflection density of 1.2 could be obtained.

Furthermore, when images were continuously formed on 1000 sheets, good images without sleeve ghosts could be obtained up to the final image formation.

In order to investigate the influence of the particle size of magnetic particles in the developer thin layer forming device of the present invention, magnetic particles of various particle sizes were mixed at a rate of 0.1 g per unit length of the developer holding member (total of 2
．． 1g) Pour into the developing device, and add 5g of the above red toner.
Table 1 shows the results of developing with 0 g added and a developing distance of 210 mm (corresponding to A4 lengthwise).

Table 1 Particle size and image quality of magnetic particles As a result, for magnetic particles with a particle size of 50 gm or less, the magnetic particles stay near the end of the elastic blade 6, hardly any circulation or vibration of the magnetic particles is observed, and the development The agent layer is very thin, resulting in an image with noticeable development unevenness, which is undesirable.
~looJLm, although some uneven development was observed, the images were quite good. At 80 NN100p, a very good image was obtained. In the case of 2004 m, fogging was observed, which was thought to be due to insufficient triboelectric charging.

Next, in order to investigate the effect of the amount of magnetic particles, in the same developing device, 0.2 g of magnetic particles with a particle size distribution of 880-150p (0.01 g per unit length (longitudinal direction) of the developer holding member) was added. cm), 1.0 (0,05), 2.1
(0,1), 10.5 (0,5), 21.5 (1,
0) Input (total amount of magnetic particles (g) present in the space in the container sandwiched between the plane connecting the center line of the sleeve 3 and the tip of the blade 6 and the plane connecting the center line of the sleeve 3 and the center line of the magnetic pole) When development was carried out using 50 g of the red toner described above, the results shown in Table 2 were obtained for the case where the magnetic particles were divided by the effective length of the sleeve (cm) and when no magnetic particles were added.

Table 2 Magnetic particle input amount and image quality According to the results, when there are no magnetic particles and a thin layer is formed only by the elastic blade 6, development unevenness is significant; Development unevenness is not noticeable, and in this range, the magnetic particles are completely restrained by the magnetic pole 5, and there is nothing that can freely move inside the developer thin layer forming device, so there is no impact on the developer thin layer forming device. Even when the magnetic particles were added, the magnetic particles were not biased. Particularly good results were obtained in the range of 0.05 to 0.1 g/Cm. Moreover, if it is 1.0 g/cm or more, uneven development, which is thought to be caused by sleeve ghost, becomes noticeable. At this time, the magnetic particles cover a considerable part of the surface of the sleeve 3,
Although the circulation was slow, no significant vibration was observed.

From the above experiments and considerations, it is understood that the presence of magnetic particles and their properties are important in the developer thin layer forming apparatus of the present invention.

Next, the relationship between magnetic particles and developer application, that is, formation of a thin developer layer, will be explained. If the amount of magnetic particles is too small, that is, about 0.1 g or less, the magnetic particles will concentrate on the tip surface of the elastic blade 6 and circulate only in this part, and the magnetic particles will be concentrated near the upstream magnetic pole of the circulating part. vibration was observed.

When magnetic particles of 0.5 g/Cm or more are present, the circulation area expands to the vicinity of the magnetic pole position, and the vibration of the magnetic particles is considerably reduced. Further, at 1.0 g/cm or more, complete circulation occurred because the magnetic particles completely covered the magnetic pole position, but almost no vibration of the magnetic particles was observed.

In addition, the circulation speed is also slower than in the case of 0.5 g/cm or less.From these results, the vibration of the magnetic particles plays an important role in scraping off the toner that was not consumed in development and supplying the toner. It is understood that

Next, another important feature of the invention, namely that the magnet 5 has only one magnetic pole on the side of the container 2, will be explained.

FIG. 6 shows a case where a plurality of (two) magnetic poles are provided on the elastic blade side with respect to the vertical line passing through the inside of the container 2, that is, the center of the sleeve 2, which is not according to the present invention. In this case, magnetic particles tend to stay between the two magnetic poles. The retained magnetic particles lie on the surface of the sleeve 2 due to the lines of magnetic force extending between the magnetic poles, and vibrations of the magnetic particles are unlikely to occur.Even if they do occur, the range of vibration is narrow, so the developer is effectively agitated. Moreover, the magnetic brush in such a lying state cannot be expected to be effective in scraping off the developer, resulting in the above-mentioned inconvenience. Therefore, the introduced magnetic particles do not work effectively, and moreover, some of the magnetic particles remain restrained by the second magnetic pole, which hardly contributes to the formation of a thin developer layer.

FIG. 7 shows the case according to the present invention, showing the container side.

That is, there is only a single magnetic pole 5 on the elastic blade side, more specifically, of the four quadrants formed by the vertical line and horizontal line passing through the center of the sleeve 3, only one exists in the quadrant where the blade end is located. has magnetic poles. According to this configuration, the magnetic particles do not "lay down" as described above, and substantially all of the magnetic particles contribute to the action of forming a thin developer layer.

Therefore, even when only a small amount of magnetic particles are used, sufficient circulation of the magnetic particles and developer and sufficient tripo application to the developer can be achieved, and the developer can be stably supplied to the surface of the sleeve 2. .

Although a non-magnetic developer was used in the above embodiments, a magnetic developer can also be used as long as it has weaker magnetism than magnetic particles and can be triboelectrically charged.

Furthermore, as shown in FIG. 8, the magnetic poles of the magnet 4 in the sleeve 3 are increased on the opposite side to the above, and a magnetic pole is also provided on the photoreceptor l side, so that as the sleeve 3 rotates, the elastic blade 6 A small amount of magnetic particles passing through the lower side may be transported and collected into the sleeve 3.

Moxibustion 1 As explained above, according to the present invention, a thin developer layer having a uniform developer layer thickness and a uniform sufficient amount of triboelectric charge is stably formed, and this developer thin layer is formed stably. By using the layer in the developing operation, good images can be stably obtained.

In addition, the magnetic particles are 0.01-0゜5 g per unit length.
Since only a small amount of / Cm is used, the magnetic particles are strongly restrained by the magnetic poles1, and even if a strong impact is applied to the developer thin layer forming device, the magnetic particles will not be biased and a stable thin layer can be obtained. .

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a developer thin layer forming apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view of the vicinity of the elastic blade of the developer thin layer forming device when the present invention is not used. FIG. 3 is a sectional view of the vicinity of the elastic blade of the developer thin layer forming device when the present invention is used. FIG. 4 is a sectional view showing the mounting structure of the elastic plate. FIG. 5 is a sectional view of a specific example of a developing device using the developer thin layer forming device according to the present invention. FIG. 6 is a cross section illustrating the state of magnetic particles when the present invention is not used. FIG. 7 is a cross-sectional view illustrating the state of magnetic particles when the present invention is used. FIG. 8 is a sectional view of a developer thin layer forming apparatus according to another embodiment of the present invention. 1) Photoreceptor 2: Container 3 Nisleeve 4: Rii stone 5: Magnetic pole 6: Elastic blade Applicant's agent Yama 1) Takashi Kuro', ``Rido 1 and de'' 1st cause Figure 2 Figure 4 m Figure 5 Cause 6 Figure 7

Claims (1)

[Scope of Claims] A developer supply container having an opening and containing a developer and a small amount of magnetic particles, and a non-magnetic cylindrical container provided in the opening and capable of endlessly moving inside and outside the container. A developer holding member, a magnetic field generating means provided inside the developer holding member, and a magnetic pole of the magnetic field generating means attached so as to come into contact with the developer holding member at a downstream position in the direction of rotation of the developer holding member. a blade having a biased end, inclined downstream from the end in the rotational direction, and elastically abutting the developer holding member; Among the four quadrants formed by a vertical line and a horizontal line passing through the center of the carrier, only one magnetic pole is located in the quadrant where the blade end is located, and the developer holding member is moved endlessly in the holding member moving direction. A developer thin layer forming device, characterized in that a developer thin layer is formed on a developer holding member downstream of the blade.