JPH0656523B2 - Development device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developing device for forming a thin layer of a developer on a developer holding member using a dry developer and using the developer for development.

BACKGROUND ART Conventionally, various devices have been proposed and put into practical use as dry type one-component developing devices. However, it is extremely difficult to form a thin layer of the dry one-component developer in any of the developing methods, and thus the developing device is configured by forming a relatively thick layer. However, at present, it is essential to develop a method for forming a thin layer of a dry type one-component developer and an apparatus therefor, which are required to improve the sharpness and resolution of a developed image.

As a conventionally known method for forming a thin layer of a dry one-component developer, JP-A-54-43037 has been proposed and put into practical use. However, this relates to the formation of a thin layer of magnetic developer. The magnetic developer must have a magnetic substance internally added in order to have magnetism, which is the fixing property and poorness when thermally fixing the developed image transferred to the transfer paper,
Since a magnetic substance (the magnetic substance is usually black) is internally added to the developer itself, there are problems such as poor coloration during color reproduction.

Therefore, as a method for forming a thin layer of a non-magnetic developer, a soft brush such as beaver's bristles is made into a cylindrical brush and the developer is adhered and applied to the brush, or the surface is made of fiber such as velvet. A method of applying to a 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 fiber brush, the amount of developer can be regulated, but uniform coating is not performed, and the fiber of the brush is simply rubbed by rubbing the fiber brush on the developing roller. Since the triboelectric charge is not imparted to the developer existing between them, there is a problem that fogging or the like is likely to occur.

Further, in such a developing method, the developer contacts the surface of the image bearing member regardless of the presence or absence of an electrostatic image, so that the developer adheres even in a non-image portion, that is, a portion having no electrostatic charge. The developer, which is not sufficiently imparted, tends to adhere to the non-image area, which causes fog to give a defective image.

OBJECT OF THE INVENTION The applicant of the present invention uses a non-magnetic developer and magnetic particles as a developing device which is completely different from the above-mentioned conventional method, provides a magnetic particle restraining member facing the developer holding member, and moves the holding member surface in the moving direction. With respect to the magnetic particle restraining member, 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 formed on the developer holding member. I have already proposed a device to do this.

However, immediately after the start of copying
The blurring of the lines was noticeable, and it became necessary to make these improvements.

The present invention improves the above-mentioned conventional developing device, guarantees good magnetic particle restraint and stability with a simple structure, and stably forms a thin layer of the developer on the surface of the developer holding member for a long period of time. An object of the present invention is to provide a developing device capable of obtaining a good copy image.

SUMMARY OF THE INVENTION The present invention provides a developer supply container having an opening, and an opening provided in the opening so as to face the electrostatic latent image carrier outside the container, and is capable of endless rotational movement inside and outside the container. A mixture of a non-magnetic developer holding member, a fixed magnetic field generating means provided inside the holding member, magnetic particles and a first non-magnetic developer, which is supplied into the container at the start of use. The first storage part for storing the mixture forming the base layer on the surface of the developer holding member facing the inside of the container until the start of use, and the second non-magnetic developer, which are started to be used. At this time, a second non-magnetic developer that is supplied to the inside of the container next to the mixture and forms an outer layer covering the base layer is stored in a state of being isolated from the mixture until the start of use. It is provided so as to face the storage section and the developer holding member. And a magnetic particle restraining member that restrains the magnetic particles inside the container so that the magnetic particles do not flow out to the outside, and when the developing device is in operation, the magnetic particles in the base layer are rotated by the rotation of the developer holding member. Along with this, a circulating motion is performed in which the second non-magnetic developer is moved upward in the vicinity of the surface of the holding member, then inverted and moved downward outside the upward moving portion. In a developing device which is taken in and dispersed in the base layer, the fluidity of the second non-magnetic developer is higher than that of the first non-magnetic developer. Therefore, it is possible to prevent the occurrence of an insufficient image immediately after the start of copying.

Embodiment 1 FIG. 1 is an explanatory view of an electrophotographic copying apparatus to which the developing device of the present invention can be applied, and shows a front sectional view of a copying machine main body of an electronic copying machine equipped with the developing device. In the copying machine of this example, a document is placed with the image surface to be copied facing downward at a predetermined position on the platen glass 19 of the reciprocating type document table 2 arranged on the upper plate of the exterior casing 1 of the machine. , And cover the document pressure plate 20 from above. Next, copy start button (not shown)
When the button is pressed, the photosensitive drum 3 is rotationally driven in the direction of the arrow, the original illumination lamp 4 is turned on, the original table 2 is moved, and other process devices are driven / energized to start copying. That is, the photosensitive drum 3 which has started to rotate is charged to a predetermined polarity by the corona discharger 5, and then the moving original table 2 is charged.
By sequentially subjecting the single-focus optical system element array 6 to slit exposure of the document image, electrostatic latent images of the document image are sequentially formed on the peripheral surface thereof. The latent image is then developed by the developing device 7.
Is developed as a toner image, and reaches the transfer corona discharger 8 parts.

On the other hand, one sheet of transfer paper P is fed from the paper feed cassette 9 by the paper feed roller 10, and the transfer paper P is transferred to the drum 3 along the guide member 12 in synchronization with the rotation of the drum 3 by the registration roller pair 11. It is fed between the corona discharger 8 and the discharger to sequentially transfer the developed image on the surface of the photosensitive drum 3. The transfer paper P is then separated from the surface of the drum 3, introduced into the fixing device 14 through the sheet path 13, receives the image fixing, and is discharged to the copy tray 16 outside the machine by the discharge roller pair 15. The surface of the photosensitive drum 3 after the image transfer is cleaned by the cleaning device 17, and is repeatedly used for image formation.

By the way, the applicant first puts magnetic particles into the developer supply container first, and the rotation range is such that the rotation range is on the inner surface of the developer holding member of the developer holding member that is rotationally driven. A magnetic particle layer (first layer) is adsorbed and held, and then a non-magnetic developer is charged and stored outside the magnetic particle layer (second layer) to form a thin layer of non-magnetic developer on the developer holding member surface. It has been proposed that a latent image is developed by forming a coating and applying a thin coating layer of the non-magnetic developer to the surface of the latent image carrier (Japanese Patent Application No. 58-151028).

FIG. 2 is a diagram showing the construction of the developing device of one embodiment of the present invention to which the above system is applied. In the figure, 21 is a developer supply container, and 22 is a developing sleeve as a developer holding member. The developing sleeve 22 is, for example, a non-magnetic sleeve made of aluminum or the like.
At the bottom of the left side wall of the horizontal opening formed in the longitudinal direction of the container,
The right semi-peripheral surface is projected into the container 21, the left semi-peripheral surface is exposed to the outside of the container, is rotatably supported by the bearing, and is laterally installed. Developer holding member 2
2 is not limited to the above cylindrical body (sleeve), and may be in the form of an endless belt that is rotationally driven. The conductive rubber roller may be used. As the conductive rubber roller, a non-magnetic sleeve made of aluminum or the like and a conductive rubber having carbon hardness of 25 to 70 ° added as a surface layer is used. The exposed surface of the developing sleeve 22 outside the container is in contact with or in contact with the surface of the latent image holding member 3 such as a photoconductor that is driven to move in the direction of the arrow a with a slight gap.

Reference numeral 23 is a fixed permanent magnet (magnet) as a fixed magnetic field generating means that is inserted into the developing sleeve 22 and positioned and held in the position and orientation shown in the figure. Even if the developing sleeve 22 is rotationally driven, this magnet 23 is shown in the figure. It is fixed and held as it is in the position and orientation. This magnet 23 has N pole 23a and S pole 2
The magnet 23 having 5 magnetic poles may be replaced with a permanent magnet and an electromagnet may be provided.

Reference numeral 24 designates a base portion fixed to the container side wall on the upper edge side of the developer supply container opening in which the developing sleeve 22 is arranged, and the tip end side is made to project inward of the container 21 rather than the opening upper edge position so that the opening upper edge becomes longer. A magnetic blade serving as a magnetic particle restraining member arranged along the magnetic blade is, for example, an iron plate bent into a V-shaped cross section.

FIG. 3 is a posture / angle relationship diagram of the magnetic blade 50 with respect to the developing sleeve 22. Reference numeral 25 is a point on the sleeve defined downstream of the magnetic pole 23a in the sleeve rotation direction and upstream of the upper edge position of the container opening in which the sleeve 22 is arranged in the sleeve rotation direction, and 1 is a center line of the magnetic blade 50. , N are normals to the sleeve 22 at the position of point 25. The magnetic blade 50 has its distal end located with respect to the sleeve 22 at a point 25 with a gap d between the surface of the sleeve 22 and the normal line n of the blade 22 to the normal line n of the sleeve 22 at the point 25. The angle δ is set so as to be inclined to the downstream side in the sleeve movement direction. θ
Is an angle formed by a normal line n passing through the rotation center O of the sleeve 12 and the normal line n, and q is the rotation center O of the sleeve 22 and the magnetic pole 2.
A line connecting the center of 3a and π is an angle formed by the line q and the vertical line m (positional angle of the magnetic pole 23a).

The gap d between the tip of the magnetic blade 50 and the surface of the developing sleeve 22 at the point 25 is 100 to 1000 μm.
And preferably 200 to 500 μm, and in this embodiment, 2
It is 50μ. If the distance d is less than 100 μ, magnetic particles, which will be described later, may be clogged and pushed out of the blade. On the other hand, if it is larger than 1000 μm, a large amount of a non-magnetic developer, which will be described later, leaks out due to vibration, and a thin layer cannot be formed.

In FIG. 2, reference numeral 26 is a magnetic particle circulation region limiting member whose lower surface is in contact with the upper surface side of the magnetic blade 50 and whose front end surface 26a is an undercut surface.

Denoted at 27 and 28 are magnetic particles and a non-magnetic developer, which are sequentially accommodated in the developer supply container 21.

The bottom plate of the developer supply container 21 is extended below the developing sleeve 22, which is a developer holding member, to prevent the developer from leaking to the outside. Further, in order to further surely prevent the developer from leaking to the outside, the extension bottom plate 21 thereof is provided.
A leakage developer collecting container portion 29 for receiving and restraining the leakage developer and a scattering prevention member 30 are arranged along the length of the tip edge of the extension bottom plate 21a on the upper surface of a. A voltage, which will be described later, is applied to this member 30.

The magnetic particles 27 have a particle size of 30 to 200 μ, preferably 70.
~ 150μ. Each magnetic particle may be composed of only a magnetic material, a combination of a magnetic material and a non-magnetic material, or a mixture of two or more kinds of magnetic particles. Then, the mixture of the magnetic particles 27 and the first non-magnetic developer is first charged into the developer supply container 21 from the first storage section 52 before the use of the developing device is started, so that the magnetic property The magnetic property as a magnetic particle restraining member from the magnetic member 31 for preventing leakage of magnetic particles or developer from the sleeve surface area where the particles 27 face the inside of the container 21, that is, the developer supply container 21 in which the sleeve 22 is disposed. A magnetic field generated by the magnet 23 in the sleeve 22 is adsorbed and held on each part of the sleeve surface area up to the tip of the blade 50, and the sleeve surface area is entirely covered as a magnetic particle layer. The second non-magnetic developer is isolated from the mixture of the magnetic particles and the first non-magnetic developer housed in the first storage part 52, and before the start of use of the developing device, the second storage part 53. It is housed in. Then, the second non-magnetic developer 28 is added to the second storage portion 52 from the first storage section 52,
By being put into the container 21 from the second storage portion 53, a large amount of the magnetic particles is stored as a second layer (outer layer) while covering the outside of the magnetic particle layer as the first layer (base layer) for the sleeve 22. Exists.

The configurations of the magnetic particle storage section 52 and the developing storage section 53 are described in Japanese Patent Application No. 58-204332 (Japanese Patent Application Laid-Open No. 60-955).
No. 61) can be used.

The magnetic particles 27 to be initially charged are originally mixed with about 2 to 70% (weight) of the first non-magnetic developer with respect to the magnetic particles. The reason for including the non-magnetic developer in the first layer composed of the magnetic particles is that even if the non-magnetic developer is added after forming the first layer and copying is started immediately, it is clear from the first sheet. This is to ensure that a good copy is obtained. When the first layer is composed of only magnetic particles, it takes time to sufficiently incorporate the non-magnetic developer from the second layer into the first layer. Therefore, after the start of copying, the first few images have low density images.

Further, once the magnetic particles 27 are adsorbed and held as a magnetic particle layer on the sleeve surface area, they do not substantially flow to one side even if the apparatus is vibrated or the apparatus is tilted to a large extent. The overall covered state is retained.

In the state where the magnetic particles 27 and the non-magnetic developer 28 are sequentially charged and accommodated in the container 21 as described above, the magnet 23
In the magnetic particle layer portion near the surface of the sleeve corresponding to the position of the magnetic pole 24, a magnetic brush 27a of magnetic particles is formed by the strong magnetic field of the magnetic pole 24.

The magnetic particle layer portion in the vicinity of the tip portion of the magnetic blade 50 serving as the magnetic particle restraining member is subjected to gravity, magnetic force and the magnetic blade 5 even if the sleeve 22 is rotationally driven in the direction of arrow b.
By the balance between the restraining force based on the effect of the existence of 0 and the conveying force in the moving direction of the sleeve 22, the stationary layer 27b which is restrained at the point 25 position on the surface of the sleeve 22 and which can move a little but is almost immovable is formed. .

When the sleeve 22 is rotated in the direction of arrow b, the magnetic pole 2
By appropriately selecting the arrangement position of the magnetic particles 27 and the fluidity and magnetic characteristics of the magnetic particles 27, the magnetic brush 27a can be set to the magnetic pole 2
4 circulates in the direction of mark c in the vicinity of 4 to form a circulator 27c. In the circulation layer 27c, the magnetic particles that are relatively close to the sleeve 22 are provided on the stationary layer 27b, which is located on the downstream side of the rotation of the sleeve from the vicinity of the magnetic pole 24 by the rotation of the sleeve 22.
Rise to the top. That is, it receives the force of pushing it up. The magnetic particles thus pushed up are absorbed by the magnetic blade 5
By the magnetic particle circulation region limiting member 26 provided on the upper part of 0,
Since the upper limit of the circulation region is determined, the magnetic blade 50 does not ride on the magnetic blade 50, falls by gravity, and returns to the vicinity of the magnetic pole 24 again. In this case, the magnetic particles having a small push-up force, which are received far away from the sleeve surface, may drop before reaching the magnetic particle circulation region limiting member 26. That is, in the circulation layer 27c, the magnetic brush 2 of magnetic particles is indicated by an arrow c due to the magnetic force and the frictional force due to gravity and magnetic poles and the fluidity (viscosity) of the magnetic particles.
7a is circulated, and during this circulation, the magnetic brush sequentially takes in the non-magnetic developer 28 from the developer layer above the magnetic particle layer and returns to the lower part inside the developer supply container 21, and the sleeve 22 This circulation is repeated with the rotation drive of the. The magnetic blade 50 does not directly participate in this circulation.

The non-magnetic developer that is sequentially taken into and mixed in the magnetic particle layer on the surface of the sleeve 22 is charged due to friction with the magnetic particles due to the flow of the magnetic particles and friction with the developing sleeve surface. in this case,
Preferably, the surface of the magnetic particles is subjected to an insulation treatment such as an oxide film or a resin which is electrostatically in the same level as the non-magnetic developer so as to reduce tribo application from the magnetic particles and receive necessary charging from the developing sleeve 22. By doing so, it is possible to prevent the influence of the deterioration of the magnetic particles and stabilize the application of the developer to the developing sleeve 22. Since this charged developer is non-magnetic, it is not constrained by the magnetic field of the magnetic pole 24, and the sleeve surface rotates and moves from the magnetic member 31 at the lower edge of the container opening where the sleeve 22 is disposed to the tip of the magnetic blade 50. In the meantime, the surface of the sleeve is evenly and thinly coated by the mirror image.

The magnetic particles in the magnetic particle stationary layer 27b in the vicinity of the tip of the magnetic blade 50 have a constraint force based on the effect of gravity and the magnetic force and the presence of the magnetic blade 50, as described above, even when the sleeve 22 rotates. The thin coating of non-magnetic developer formed on the surface of the sleeve 22 is constrained by the balance with the conveying force of the moving direction of 22 and does not pass through the gap 2 between the tip of the magnetic blade 50 and the sleeve 22. As the sleeve 22 rotates, only the layer passes through the gap d and is rotatively conveyed to the latent image holding member 3 side, and approaches and faces the latent image holding member surface. 28a is a developing sleeve 22
3 shows a thin coating of non-magnetic developer formed on a surface. The approaching facing portion between the developing sleeve 22 having a thin layer of the non-magnetic developer and the latent image carrier 11 is referred to as a developing portion 32.

In the developing section 32, the non-magnetic developer layer 28a on the side of the developing sleeve 22 is selectively transferred to and adheres to the surface of the latent image holding member 3 corresponding to the latent image pattern by the electric field of the bias power source 34 to develop the latent image. Are performed sequentially. The bias power supply 34 may be alternating current or direct current.

The developing sleeve surface which has passed through the developing section 32 and is consumed by being selectively used in the developing process returns to the inside of the developer supply container 21 again by the subsequent rotational driving of the sleeve, and contacts the magnetic particle layer again. The cycle of receiving the coating of the non-magnetic developer contained in the layer is repeated, and the development of the surface of the latent image holding member 3 is continuously executed. As described above, the magnetic particle circulation layer 27c is used to sequentially replenish the magnetic particle layer from the reservoir layer of the non-magnetic developer 28 existing on the outer side of the circulation layer 27c of the magnetic particles, thereby replenishing the developer naturally. In order to prevent so-called ghost image development of the developing sleeve, the developer layer that has not been used for development is once scraped off from the surface of the developing sleeve which has returned to the inside of the container 21 and rotated, and then scraped by a scraper stage (not shown). The developer layer may be scraped off so that the surface of the sleeve is brought into contact with the magnetic particle layer to coat the developer.

To the non-magnetic developer 28, silica particles for enhancing fluidity, or abrasive particles for externally polishing the surface of the photosensitive member, which is the latent image holding member 3 in the transfer type image forming method, are externally added. Good. Alternatively, the non-magnetic developer 28 containing a small amount of magnetic particles may be used.

Thus, in the developing device of the above example, the non-magnetic developer can be formed into a uniform thin layer having a sufficient amount of charge on each surface of the developer holding member, and can be stably coated for a long period of time. Therefore, this thin developer layer makes it possible to develop the latent image on the latent image holding surface clearly and with good resolution.

Further, since a magnetic developer having a vivid color can be obtained, it is possible to obtain a high-quality color copy having excellent color reproducibility (single color, multicolor, natural color).

In the case of the two-layer structure described above, the magnetic particle layer including the stationary layer and the circulation layer is formed near the outer surface of the developing and holding member 22 from the beginning, and the developer layer does not contain magnetic particles at all. Due to the small amount, the state of the magnetic particle layer is maintained substantially constant even if the operation is continued for a long time, does not change, and the magnetic particles are not consumed. In this sense, the magnetic particles in the magnetic particle layer can be regarded as a part of the developing device, not the developer or a part thereof.

By the way, in the developing device having the above-described structure, when the unused device is used for the first time, ground fog and line scattering may occur in the non-image area for several sheets to several tens of losses immediately after the opening of the copy. Alternatively, there may occur a problem that the copy image density is low even when a stable number of sheets are taken and a stable image should be obtained after the start of copying.

The present inventor analyzed the cause as follows.

Regarding the developer concentration in the first layer of the developing device having the above configuration,
There is a stable predetermined density value reached after the developing operation is continued for a certain period of time, and good development can be stably obtained at this density value.

As described above, the first layer takes in the non-magnetic developer in the second layer by circulating the magnetic particles therein, and the circulation speed depends on the concentration of the developer in the first layer. That is, when the developer concentration is low, the circulation speed is high, and a large amount of the non-magnetic developer in the second layer is taken in. Conversely, when the developer concentration is high, the circulation is low and the developer uptake is reduced. Moreover, immediately after a large amount of the developer is taken in, the circulation in the first layer does not immediately slow, but rather slows with a slight delay. This is only when the developer taken into the first layer is loosened by the magnetic particles in the first layer and dispersed almost uniformly,
This is because the circulation speed decreases.

Here, it is assumed that the initial concentration of the developer in the first layer is lower than the above predetermined concentration. In this case, as described above, the circulation in the first layer is rapid, and a large amount of the non-magnetic developer is taken in from the second layer, so that the excess developer is contained in the first layer. The triboelectric charge for the developer coated on the surface of the developer holding member 22 is insufficient. When such a developer and coating reach the developing portion, the developer adheres to the non-image portion of the photoconductor, causing background fog. Further, the developer attached to the image portion also has a small amount of electric charge, so that the adhesive force to the photoconductor is weak, and the developer easily scatters around the line image during image transfer. This is considered to be the cause of the inconvenience immediately after the start of copying.

To avoid this, from the above analysis, the developer concentration in the first layer may be increased and selected in advance so as to obtain a slow circulation. However, in this case, even after a certain amount of time immediately after the start of copying, the circulation remains slow even at the time when originally stable circulation should be obtained, and the density of the copy image is low. This is considered to be another cause of the above inconvenience.

Of course, if the initial amount of the developer contained in the first layer is matched with the stable predetermined concentration, these disadvantages do not occur.

As can be seen from the above, the amount of the initial developer in the first layer cannot be arbitrarily changed.

However, it is preferable to lower the initial concentration of the developer in the first layer. When the developer concentration is high, the volume of the first layer increases. When the mixture forming the first layer is charged into the developer range insulating member from the storage portion provided in the developer container, if the volume is large, it is necessary to increase the volume of the storage portion for that purpose. . Since this volume is a space that does not change after the first layer mixture is charged, it is desirable to make it as small as possible due to the structure of the developing device.

In the present invention, the first non-magnetic developer and the second layer in the first layer (base layer) are used in order to reduce the developer concentration in the first layer mixture as much as possible and prevent the above-mentioned inconvenience immediately after the start of copying. The fluidity of the two non-magnetic developers in the (outer layer) was made different. Specifically, the fluidity of the first non-magnetic developer was set lower than that of the second non-magnetic developer. As a method for achieving this, for example, the amount of colloidal silica externally added to the developer is made smaller in the first nonmagnetic developer than in the second nonmagnetic developer. Alternatively, the particle size of the first non-magnetic developer may be smaller than the particle size of the second non-magnetic developer. Further, external additives other than silica may be used for one or both of them to change the fluidity. Different kinds of silica may be used. Further, the resin or the internal additive constituting the developer may be changed. The fluidity can be measured by a generally used powder measuring method. That is, there is a method in which the inclination angle (repose angle) of the bottom surface of a mountain-shaped vertical section formed by gently dropping and depositing a measurement sample on a flat surface is used as a measure of fluidity. In addition, a predetermined mesh is arranged from the top to the bottom in a rough order, toner is put on the uppermost portion of the mesh, and a predetermined vibration is applied to obtain the toner remaining amount in each mesh. There is a method of multiplying this amount by a predetermined coefficient to obtain the cohesion degree of the toner. In the present invention, the fluidity of the toner is represented by the degree of aggregation according to the latter measuring method.

Now, a specific example using the developing device shown in FIG. 2 will be described below. In FIG. 2, φ2 is used as the developer holding member 22.
0 The surface of an aluminum sleeve is treated with an irregular type side plast with alundum abrasive grains, and the magnet 23 is magnetized with two poles so that the north pole and the south pole are the positions shown in FIG. Was used at π = 95 ° in FIG.

The magnet of FIG. 2 has a maximum surface magnetic flux density of about 500 gauss, but it is preferable to further increase the strength of the developer used, especially the developer having a slightly poor fluidity. Visual observation revealed that the magnet having a surface magnetic flux density of about 800 Gauss doubled the circulation in the direction of FIG. 2c.

The magnetic blade 50 is a 1.2 mm thick iron plate plated with chemical nickel. As the material of the iron plate, SPC steel plate, silicon steel plate, permalloy and the like which are commonly used industrially are desirable. Further, these magnetic bodies may be magnetized so as to strengthen the magnetic field in the tangential direction. In the apparatus of FIG. 2, θ = 30 °, δ =
The angle was 85 ° and the distance between the blade and the sleeve was 250 μ. δ = 9
The angle may be 0 °, that is, the tangential direction of the sleeve, but if the mechanical accuracy is poor, the magnetic blade may abut against the sleeve, and if δ> 90 °, this tendency becomes more remarkable.
This is not preferable in restraining the magnetic particles.

In this embodiment, the first layer developer has a particle size of 100-
Iron particles (maximum magnetization 190 emu / g) of 80μ (150/200 mesh), 100 parts of styrene / butadiene copolymer resin, and 5 parts of copper phthalocyanine pigment to 5 parts of copper phthalocyanine pigment are used. ．
A blue toner in which 1.0% of colloidal silica is externally added to the toner powder in the first layer developer as the second layer developer, which is used by mixing with 4% of the externally added blue toner in a ratio of 10: 1. Was used. As the fluidity evaluation of the toner by the measurement of the aggregation degree, 0.4% of the externally added toner has an aggregation degree of about 17%.
Approximately 9.6% of toner with 0% external addition and lower fluidity with 0.4% of externally added toner, and about 100 g was used as an input amount.
A good coating was obtained with a coating thickness on the sleeve of about 50-100 μm and a toner tribo charge on the sleeve of +10 μcoul / g as measured by the blow-off method.

The developing device of this embodiment was incorporated in a PC-10 type copying machine manufactured by Canon Inc., and a bias power source 34 having a frequency of 16 was used.
-3 to AC voltage of 00Hz, peak-to-peak value 1300V
Using a superposed DC voltage of 00V, sleeve 2
When the development was carried out with the distance between 2 and the OPC photosensitive member 3 set to 250 μm, no background fog or scattering immediately after the start of copying was generated, and a good blue image was obtained until the toner was consumed and disappeared.

Although a non-magnetic developer is used in this embodiment, a magnetic developer can be used as long as it has magnetic properties that are significantly weaker than magnetic particles and tribo-charging is possible. In addition, although the developer supply container has been described as an example of a single-use type developing device in which the developer supply container is integrated, a developer supply container has been described. The present invention can be applied to a replaceable supply cartridge. Also,
As the developing method, the non-contact developing method described in Japanese Patent Publication No. 58-32375 utilizing an alternating bias electric field is preferable, but the developing method is not limited to this and may be applied to the contact developing method.

The developing bias may be a DC electric field regardless of the periodic displacement electric field.

EFFECTS OF THE INVENTION According to the present invention, the fluidity of the second non-magnetic developer incorporated into the base layer from the outer layer by the circulating motion of the magnetic particles of the base layer is higher than that of the first non-magnetic developer. This second non-magnetic developer quickly and uniformly disperses in the base layer.
Therefore, the circulation speed of the magnetic particles can be quickly adapted to the amount of the non-magnetic developer in the base layer, and it is possible to prevent the non-magnetic developer from being excessively taken into the base layer, thus preventing fog in the developed image. In addition, the image quality of the line image can be improved.

Further, it has become possible to form a clear color image using a non-magnetic developer.

[Brief description of drawings]

FIG. 1 is a front sectional view of an electrophotographic copying and developing apparatus incorporating the developing apparatus of the present invention, FIG. 2 is a sectional view of the developing apparatus of the present invention, and FIG. 3 is an arrangement of a developing sleeve and a magnetic blade of the apparatus. It is explanatory drawing of a posture and an angle. Reference numeral: 3 ... Latent image holding member, 21 ... Developer supply container, 22 ...
... developer holding member, 23 ... fixed magnetic field generating means, 24 ...
... magnetic particle restraining member, 27 ... magnetic particle, 28 ... non-magnetic developer.

Claims (1)

[Claims] 1. A developer supply container having an opening, and a non-magnetic material provided in the opening so as to face the electrostatic latent image carrier outside the container and capable of endless rotation movement inside and outside the container. A developer holding member, a fixed magnetic field generating means provided inside the holding member, and a mixture of magnetic particles and a first non-magnetic developer, which are supplied into the container at the start of use. A first storage part for storing a mixture forming a base layer on the surface of the developer holding member facing the inside of the container until the start of use, and a second non-magnetic developer, A second storage unit that stores a second non-magnetic developer that is supplied to the inside of the container next to the mixture and forms an outer layer that covers the base layer, in a state of being isolated from the mixture until the start of use. And provided to face the developer holding member, A magnetic particle restraining member for restraining the magnetic particles inside the container so as not to flow out to the outside, and the magnetic particles in the base layer are rotated by the rotation of the developer holding member during the operation of the developing device. A circulation movement is performed in which the second non-magnetic developer is moved upward from the outer surface of the lever holding member and then inverted and moved downward outside the upward movement portion. In the developing device which is taken in and dispersed in the developing device, the fluidity of the second non-magnetic developer is higher than the fluidity of the first non-magnetic developer.