JP2556506C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a two-component developing method for developing using magnetic carrier particles and toner particles.
The present invention relates to a developing device of the type. The present invention relates to a display device for image recording and forming, a printer, and a facsimile electrophotographic apparatus.
This is a developing device that can be applied to various devices. [Background Art] Applicants form a thin layer of developer on a developer carrier, and contact the thin layer of developer with a latent image.
And a developing device that applies an alternating electric field to the approaching portion to perform development.
Nos. 58-32375 and 58-32377). This device has a development efficiency (toner that can be consumed for development among toners existing in the development section).
Is very useful in terms of miniaturization, etc.
Since the developer used is a one-component magnetic toner, the toner must contain a magnetic material.
Is indispensable, so that the fixability of the developed image is poor,
It has disadvantages such as bad things. As a device to compensate for this drawback, the applicant uses non-magnetic toner and uses non-magnetic toner.
Developed a method and apparatus for forming a thin thin layer on a developer carrying member, and developed a non-magnetic toner
A developing method of developing by applying an alternating electric field with a thin layer of only
A device has been proposed (JP-A-58-143360 and JP-A-59-101680).
). This maintains the advantages of the developing device using the magnetic toner described above,
This is useful because the disadvantages caused by the inclusion of the material have been eliminated, but the density of the developed image is relatively low.
Relatively low and the negative characteristics described below (image density decreases with increasing latent image potential)
Defects) in developing characteristics, such as the case where Further, what is known as a so-called two-component magnetic brush developing method (for example,
No. 53-93841), a non-magnetic developer can be used,
Because the ratio of consumable toner in the magnetic brush is small, brushes with low development efficiency
Traces of rubbing are generated on the developed image like sweeping. Particularly, in the developing section, the moving direction of the developer carrier is the same as the moving direction of the electrostatic latent image carrier.
Is reversed, the magnetic brush strongly rubs the electrostatic latent image surface.
There is a disadvantage that the layer sweep pattern is strongly generated on the image. [Object of the Invention] The present invention has a high developing efficiency and can form a developed image having a high image density.
It is an object of the present invention to provide a developing device that does not generate a sweep pattern and has no negative characteristics. SUMMARY OF THE INVENTION In the present invention, the moving direction of a developer and the moving direction of an electrostatic image carrier in a developing section are reversed.
A large amount of magnetic particles are developed as in the conventional two-component magnetic brush development.
Magnetic particles constrained by the fixed magnetic field in the developing section instead of being supplied to the developing section.
By supplying a small amount of magnetic particles that open the surface of the imaging agent carrier,
An excellent high-quality developed image can be obtained. Moreover, the magnetic particles are generated by the alternating electric field.
The toner particles on the surface and the surface of the developer carrier can be effectively used, and the present invention is effective for both contact development and non-contact development. Embodiment FIG. 1 is a cross-sectional view of a developing device according to an embodiment of the present invention having the above-described system.
. The latent image carrier 1 is made of an insulating drum for electrostatic recording or α-Se, Cds, ZnO _Two ,
OPC, photosensitive drum or photosensitive belt having photoconductive insulating material layer such as α-Si
It is. The latent image carrier 1 is rotated in the direction of arrow a by a driving device (not shown).
Reference numeral 22 denotes a developing sleeve which is close to or in contact with the latent image carrier 1, for example,
It is made of a non-magnetic material such as aluminum and SUS316. Developing sleeve 2
Reference numeral 2 denotes a left substantially half circumferential surface formed in a horizontally long opening formed in the longitudinal direction of the container on the lower right wall of the developing container 36.
It is made to protrude into the container 36, and a substantially right half peripheral surface is exposed to the outside of the container to be rotatably supported.
And is driven to rotate in the direction of arrow b. Reference numeral 23 denotes a fixed magnet inserted into the developing sleeve 22 and positioned and held in the illustrated position and orientation.
This is a fixed permanent magnet (magnet) as a field generating means. Even if the developing sleeve 22 is driven to rotate, the magnet 23 is fixed at the position and posture shown in the drawing.
Will be retained. The magnet 23 has N magnetic poles 23a, S magnetic poles 23b, and N magnetic poles.
It has four magnetic poles 23c and 23d S-poles. Magnet 23 is electromagnetic instead of permanent magnet
Stones may be provided. Reference numeral 24 denotes an upper edge side of the developer supply opening where the developing sleeve 2 is disposed,
It is fixed to the wall, and the front end side is protruded outside the
A non-magnetic blade as a developer regulating member disposed along the length, for example, SuS
316 is bent into a cross-section path. Reference numeral 26 designates the upper surface of the non-magnetic blade 24 in contact with the lower surface, and the front end surface thereof
61 is a magnetic particle limiting member. 27 is a magnetic particle having a particle size of 20 to 100 μm, preferably 30 to 80 μm.
Apparent density of about 2.4 to 2.8 g / cc ferrite particles (maximum magnetization 60 to 70 emu)
/ G) can be used. If it is smaller than 20μ, the ears on the developing sleeve are poor, and
Tend to be. If it is larger than 100μ, the ability to apply tribo to the toner will decrease.
Also, the photosensitive plate is easily damaged. 37 is a non-magnetic developer toner. Numeral 31 denotes no magnetic particles 27 from the lower part of the developing container 36 in which the developing sleeve 22 is disposed.
In order to prevent leakage of the non-magnetic toner particles 37, the developing sleeve
A magnetic material disposed opposite the probe 22, for example, a plated iron plate
It is. Recovery of the magnetic particles 27 by the magnetic field between the magnetic body 31 and the magnetic pole 23d of S polarity
A sealing effect that achieves leakage prevention is obtained. Reference numerals 38 and 35 denote a toner storage container and a magnetic particle storage container, respectively. Reference numeral 40 denotes a sealing member which seals the toner accumulated in the lower portion of the developing container 36 and has elasticity.
The sleeve 22 is bent in the rotation direction, and the surface side of the sleeve 22 is elastically
Pressing. The seal member 40 permits the developer to enter the inside of the container.
Thus, the end portion is provided on the downstream side in the sleeve rotation direction in the contact area with the sleeve. FIG. 2 is a view showing a main part near the limiting member 26 on the downstream side of the magnetic material 31 shown in FIG.
It is clear that the operation can be stabilized by combination with the magnetic member 31.
. L _Four Is the horizontal plane passing through the center Os of the developing sleeve, and Q is the center Os of the developing sleeve.
It is a vertical plane that passes through the first quadrant 100, the second quadrant 101, the third quadrant 102, and the fourth quadrant.
Limit 103. In the drawing, reference numeral 241 denotes a regulating end of the regulating member 24, and
The closest distance d to the facing part 242 on the surface of the probe 22 _Two Fixed with
Have been. The developer guide diagram 261 shows how the sleeve rotates toward the regulating member side end 263.
A slope is formed from the upstream end 262 with respect to the direction b, and gradually forms a slope with the surface of the sleeve 22.
It faces the regulating member 24 while decreasing the distance. Guide surface end 263, close to regulating member
Here, the developer is regulated by the end 241 of the regulating member 24. end
263 is a distance (d ₁ + D _Two ) Located through. d ₁ Is end 2
63 is the distance between the end 241 and d ₁ > 0. Here, the facing part 242 on the sleeve
A plane P ′ that is parallel to the tangent plane P and passes through the end 263 is defined. Guide surface 261
The angle ρ with respect to the plane P ′ assumes the developer guiding effect of the guide surface and the movement of the developer.
Important as a parameter. L ₁ Is a portion that gives the maximum magnetic flux density of the magnetic pole 23a.
A straight line passing through the center Os of the sleeve, L _Two Represents the regulating agent end 241 and the center Os of the sleeve.
The angle β is a straight line L ₁ And the straight line L _Two And the angle between them. This angle β is also developed
It is an important parameter in the drug control area. L _Three Is the end 262 of the guide surface 261
Is a straight line passing through the center Os of the sleeve, and a straight line L ₁ Form an angle β (> 0) between
I do. Note that the vertical plane Q and the straight line L _Two Is δ. In the following example, the regulating member
24 is a non-magnetic blade, non-magnetic toner particles for toner, and ferrite for carrier
With resin coated 10 ⁷ Magnetic particles of Ω · cm or more were used. The end 241 of the non-magnetic blade 24 and the surface of the developing sleeve 22 at the point 241
The distance d _Two Is 50 to 600 μm, preferably 150 to 500 μm. This distance d _Two Is 50
If it is smaller than μm, magnetic particles to be described later are clogged during this, and the developer layer tends to be uneven.
Low density due to the inability to apply the developer necessary for good development
There is a disadvantage that only a developed image having many irregularities can be obtained. If it is larger than 600 μm,
The amount of the developer applied on the image sleeve 22 is increased, and a predetermined developer layer thickness can be regulated.
The magnetic particles adhere to the latent image carrier, and the
The development restriction by the agent limiting member 26 is weakened, and the toner tribo is insufficient and fogging is likely to occur.
Disadvantages. Distance d between non-magnetic blade end 242 and guide surface end 263 ₁ Is 0.5-5.0m
m, preferably 1.5 to 4.0 mm. This distance d ₁ Is smaller than 0.5 mm
In this case, the pressing force of the developer on the developing sleeve by the developer limiting member 26 increases.
The triboelectric potential of the developer abnormally rises and the desired development characteristics cannot be obtained.
When a toner or the like is used, the toner may be fused to the developing sleeve 22. This distance d ₁ Is larger than 5.0 mm, the developer on the developing sleeve 22
The pressing pressure of the toner is too weak to give a sufficient tribo to the toner. of course
It has an automatic toner supply mechanism like a general two-component developing device,
In the case where sufficient frictional electrification is performed between ₁ 5.0 mm
It is possible to set above. Also, (d ₁ + D _Two ) Is 5.6mm or less, preferred
It is better to be 5 mm or less. The angle ρ is 0 <ρ ≦ 45 when the upward direction from the plane P ′ is a plus direction, preferably
Is 0 <ρ ≦ 30. When ρ <0 °, the developing sleeve 22 and the non-magnetic blade 2
4 has a sharp wedge-shaped space formed by the end 241 and the guide surface 261 and is filled with developer.
In rare cases, the pressure may increase, and the frictional charging potential may be abnormally increased, and the toner may be fused. ρ>
In the case of 45 °, the developer is pressed against the developing sleeve 22 by the developer limiting member 26.
As a result, the effective force of the developer limiting member 26 is lost. Is between 0 and 35 degrees, preferably between 5 and 25 degrees. When θ <0, the development formed by the magnetic force, mirror image force, cohesive force, etc. acting on the developer
The thin agent layer becomes sparse and uneven, and when θ> 35 ° is exceeded, a non-magnetic blade
In this case, the amount of the applied developer increases, and it is difficult to obtain a predetermined amount of the applied developer. The setting angle δ of the non-magnetic blade 24 is determined from the vertical line Q due to the relation of the moving state of the developer.
When added in a counterclockwise direction, it is preferable that -60 ° <δ <120 °. Here, when FIG. 2 is viewed as the first to fourth quadrants, the developer limiting member 26 is
Horizontal plane L passing through the rotation center of the developer carrying member 22 during image formation _Four Located above,
With respect to the vertical plane Q passing through the rotation center Os, the developer guide surface 261 is on the left side (second
It exists over both the quadrant 101) and the right side (the first quadrant 100). this is
In addition to the operation of the guide surface 261 that the developer can be stably supplied to the developer regulating region.
In addition, the developer can be further supplied to the restricted area by gravity. The developer regulating member 24 has a horizontal plane L passing through the rotation center of the developer carrying member. _Four Is located in the first quadrant 100 defined by
The regulating end 241 is separated from the surface of the developer carrying member 22. this is
Since the regulating end is on the downstream side in the rotation direction b with respect to the vertical plane Q, the regulating end
241 is densely packed in the container space near, and forms a stable magnetic particle occupation state
This is a preferred configuration for A first quadrant 100 to a fourth quadrant 103 as a development area in FIG. 1 and a seal area
And a third quadrant 102 as ₁ = 1.5mm, d _Two = 250 μm, θ = 1
When 8 °, δ = 15 ° and ρ = 20 ° are set, a magnetic particle layer is formed on the sleeve surface.
Then, a toner particle layer was formed on the magnetic particle layer, and development was performed. Even if the sleeve 22 is rotationally driven in the direction of the arrow b, the magnetic particle layer has a magnetic force and a gravitational force.
Of the sleeve 22 by the balance between the constraint force based on
Moves slowly as you move away from the surface and can move slightly above the magnetic particle layer
Form an almost immobile stationary layer. Of course, some fall under the influence of gravity. Therefore, the arrangement positions of the magnetic poles 23a and 23b and the fluidity and magnetic characteristics of the magnetic particles 27
By appropriately selecting the magnetic particle layer, the magnetic particle layer is conveyed and moved in the direction of the magnetic pole 23a closer to the sleeve.
A moving layer is formed. Due to the movement of the magnetic particles, the magnetic particle layer (first layer) becomes a toner layer (first layer).
The toner is taken in from the second layer), and the toner is rubbed with the magnetic particles or the sleeve.
Is transferred to the developing area with the rotation of the sleeve 22 due to the triboelectric charge and is supplied to the developing area.
Is done. The movement of the magnetic particle layer is determined by the fluidity and magnetic force of the developer and
When the toner content is low, the stationary layer becomes smaller, and most of the magnetic particle layers become faster.
Move to take in toner from the toner layer. Also, if the toner content is high,
The stationary layer becomes larger, and the moving layer of the magnetic particle layer is separated from the toner layer covered by the stationary layer.
Contact cannot be made, and almost no toner is taken in. Therefore nature
A certain amount of toner content is maintained. Next, the vicinity of the non-magnetic blade 24, which is a developer application amount regulating member, and the limiting member 26
Will be described. The limiting member is a toner supply to the developer regulating section.
It is not just mechanically preventing unwanted entry. As described above, the member 26 is
In the regulation area surrounded by the sleeve, the magnetic pole N ₁ With the rotation of the sleeve by the pole
The conveyed magnetic particles are packed along the guide surface 261 of the limiting member 26 and
It becomes tedious. In this area, the magnetic particles and blades
The magnetic particles that are flowing out of the container are dynamically replaced by magnetic particles.
Although they are in a state of collision due to collision with each other, in a substantial packing state
Has become. For this reason, tribo-impartation of the toner from the magnetic particles or the sleeve
Is carried out, and the trie which has been conveyed with weak force on magnetic particles or sleeves
The toner with a small amount of toner is separated from the magnetic particles or the sleeve. In other words, Tona
Sorting and charging improvement. Therefore, the toner sufficiently given the tribo-application can be used for development. Also, when transporting magnetic particles
The non-uniform state is also leveled in the space, and the uniformization and stabilization of the coating of the magnetic particle layer is also achieved.
Achieved. Accordingly, the guide surface 261 is indispensable for the limiting member 26, and the slope
And the volume of the space greatly affect the packing state of the magnetic particles in the space
. On the other hand, the magnetic pole 23a fixed to this region is
The magnetic particles in the solid state are rearranged along the lines of magnetic force. The packing condition in the space
There are some points of instability with respect to ribotherapy, and a certain amount of
Requires a locking state. It has been transported almost tangentially over the sleeve
Stirring of magnetic particles to form a magnetic brush with a force perpendicular to the direction
Not only the effect but also the loosening effect works, giving the toner a tribo and magnetic
Uniform and stable application of the particle layer is further promoted. At this time, depending on the surrounding configuration,
If the concentrated developer is subjected to a large amount of pressure, the developer may be clogged too much.
By opposing each other, excessive pressure concentration in the regulation area is prevented, and developer
It is considered that the concentration and the stable high-density ratio of the magnetic particles can be maintained. Follow
The magnetic pole 23a is provided under the condition that magnetic particles are easily packed in the space, for example, as shown in FIG.
In the case of δ <0 shown, it works particularly effectively. Due to the above restriction area, a stable amount of magnetic particles and
The minutely charged toner particles can be formed as a developer thin layer. Therefore, the development area 10
The developing effect at 0 to 103 becomes stable. Then, it is transported to the developing section described above.
The toner particles carried on at least the surface of the developer carrying member of the developer are electrostatically charged.
An alternating electric field forming means for forming an alternating electric field for transferring to the latent image carrier in the developing section;
In the developing section, the electrostatic latent image carrier is defined by the developer carrier.
The volume occupied by the magnetic particles of the developer conveyed to the developing unit with respect to the volume of the space
It was confirmed that a great effect was obtained for the developing method and the apparatus in which the ratio was 1.5% to 30%. FIG. 3 shows a case where the magnetic body 50 is installed on the non-magnetic blade side of the developer limiting member 26.
Is shown. In this case, it is preferable to provide the magnetic body 50 at a position facing the magnetic pole 23a.
Not good. This is because a strong concentrated magnetic field is generated between the magnetic pole 23a and the magnetic pole 23a.
And the effect of stirring and loosening the magnetic particles by the magnetic pole 23a is reduced.
It is. However, a magnetic material is provided in the regulating portion and the magnetic particles
Implementing magnetic regulation increases the tolerance of the gap between the regulating member and the sleeve, and is effective.
It is. Also, when comparing the magnetic particles or toner adhering to the sleeve,
The amount of charge of the toner attached to the magnetic particles is smaller than that of the toner attached to the magnetic particles.
The reason for this is that magnetic particles are also transported along with the movement of the sleeve, so the toner on the sleeve is
This is because the chance of the particles being rubbed by the magnetic particles is reduced. This pickpocket
To raise the toner on the sleeve to a predetermined value, collect the toner on the sleeve.
It is necessary to rub extremely. That is, in the vicinity of the sleeve surface,
The presence of magnetic particles that cause a shift in speed is required. However, simply reducing the transportability of magnetic particles is due to the aforementioned
It is not possible considering the use. In addition, as described above, the regulating portion
A magnetic material is placed opposite to generate a concentrated magnetic field, and the magnetic particles slide on the sleeve.
As described above, it is possible to improve the magnetic pole in the space created by the developer circulation regulating member 26.
The effect of arranging the large magnetic force generating portion is reduced. Therefore, in this embodiment, the downstream side of the magnetic pole 23a with respect to the sleeve rotation direction.
The magnetic body 50 is provided on the surface of the sleeve, and the magnetic field lines on the blade side of the magnetic pole 23a are substantially on the sleeve surface.
It was configured to concentrate in the tangential direction. As a result, magnetic particles only near the sleeve surface
Forms a magnetic brush along the sleeve surface, rubs the toner on the sleeve,
The tribo application of the toner on the sleeve could be increased. When the length between the end 263 and the end 262 is a straight line (flat surface), the guide surface 261 preferably has a length of 5 mm or more and 15 mm or less with respect to the rotation direction.
Good. If it is less than 5 mm, the developer guiding effect is halved and the magnetic particles
It is not preferable because it may rise above the
This is not preferable from the viewpoint of miniaturization. In addition, the straight line L ₁ , L _Three Angle β
Preferably, the angle is 5 ° or more. This is because the magnetic pole 23a as the magnetic field generating means has an angle (θ
+ Β), the effect of the magnetic field on the regulation region defined by the regulation member 24 or the member 261 (
(Including the one containing the magnetic substance 50) and stably exerts it in satisfying the working relationship.
Important for. The magnetic flux density of the magnetic pole 23a is preferably 600G or more, more preferably 700G or more.
No. This is because the application state of the developer is not affected by the change in the toner content of the magnetic particle layer.
This is because the higher the magnetic flux density of the magnetic pole, the more stable the magnetic pole. Especially toner content
In the developing device of the present invention which does not have an automatic toner replenishing device for maintaining
Preferably, the magnetic flux density is 0 G or more. In FIG. 1, the magnetic pole 23c is a developing magnetic pole.
And a magnetic flux density of 800 G or more to prevent the magnetic particles from adhering to the latent image.
Good. It goes without saying that the present invention includes any combination of the above-described configurations. In any case, the present invention provides high image quality that cannot be obtained by conventional developing methods and apparatuses.
It is an advantage that the developing device can be made a compact disposable type.
It has an excellent effect. The toner 37 is magnetized by rotating in the direction of arrow d in close proximity to or in contact with the magnetic particle layer.
Supply to the particle layer. A toner storage container that stores toner adjacent to the developing container 36 in a substantially horizontal direction.
The toner storage container is provided with a toner carrier 38 for feeding toner into the developing container 36.
A feeding member (10) is provided. The S magnetic pole 23b acts on the developer in the developing container 36 by the action of the magnetic field with the cut magnetic pole 23a.
27 is controlled, and the magnetic seal draws the magnetic field by the action of the magnetic field with the N magnetic pole 23d.
A brush is formed to prevent the developer from leaking. The N magnetic pole 23d is a collecting magnetic pole for collecting the developer after development, and is a magnetic seal tip.
It is arranged on the upstream side in the developing sleeve moving direction. Here, the volume ratio of the magnetic particles in the developing section will be described. What is the "development section"
This is where toner is transferred or supplied from the sleeve 22 to the photosensitive drum 1.
. "Volume ratio" is the ratio of the magnetic particles present in the volume of the developing section to the volume of the developing section.
Volume percentage. This volume ratio has an important effect in the above developing device.
And 1.5% to 40% (more preferably 30%), especially 2.6%
It is very preferable to set it to 26%. At less than 1.5%, a decrease in the density of the developed image is observed,
A significant concentration difference occurs between the portion where the ears 51 exist and the portion where the ears 51 do not exist.
That is, the thickness of the developer image formed on the surface of the sleeve 22 is generally non-uniform.
It is not preferable in terms of becoming. Up to 40%, the sleeve surface can be slightly opened, but if it exceeds 30%, the magnetic particles covering the sleeve surface increase, so the latent image carrier
The surface is strongly rubbed, and uneven sweeping is likely to occur. In addition, magnetic particles close the sleeve surface
The toner applied on the sleeve may fly due to the
Can be prevented, reducing the effect of smoothing out the unevenness created by the magnetic particles
. In particular, for the present invention, the above-mentioned conditions listed as preferable development methods increase the volume ratio.
Rather than monotonically deteriorating or increasing the image quality according to the addition or reduction,
Sufficient image density can be obtained in the range of 5 to 30%.
If the image quality is deteriorated, and the image quality is within the above range, the sleeve go
It is based on the fact that neither strike nor sweeping or fogging occurs. The former painting
The quality degradation is thought to be due to negative properties, the latter being due to the increased abundance of magnetic particles.
The surface of the sleeve 22 cannot be opened, and the amount of toner supplied from the surface of the sleeve 22 is large.
It is thought to result from a reduction in width. If it is less than 1.5%, the reproducibility of the line image is inferior and the image quality density is remarkably reduced.
On the other hand, if it exceeds 30%, the magnetic particles damage not only the developed image but also the surface of the photosensitive drum.
And the problem of transfer and fixation caused by adhering as part of the image. When the presence of magnetic particles is close to 1.5%, a large area uniform high-density image
When partial development unevenness called "arabi" occurs when reproducing black
Under different circumstances), it is preferable to use a volume ratio in which these are unlikely to occur.
. This value is based on the fact that the volume ratio of the magnetic particles to the developing part is 2.6% or more.
Is a more preferable range, and when the presence of the magnetic particles is close to 30%,
When the toner supply from the sleeve surface is delayed around the area where the magnetic particles
(When the development speed is high, etc.), which may cause scale-like density unevenness when solid black is reproduced.
There is. As a certain range for preventing this, the above volume ratio of the magnetic particles is 26%.
The following are more preferred. If the volume ratio is in the range of 1.5 to 30% (set to 4% in the embodiment), the spike 51 is placed on the surface of the sleeve 22 as shown in FIG.
Since it is formed in a sparse state to a desirable extent, there is no need to strongly rub the latent image carrier.
The toner on both the sleeve 22 and the ears is sufficiently released to the photosensitive drum 1
And the toner 100 on the sleeve also flies in an alternating electric field, so that almost all
High development efficiency with no sweeping unevenness because all toner can be consumed for development
Ratio (the ratio of toner that can be consumed for development among the toner present in the developing section) and high
The image density is obtained. Preferably produce small but intense spikes of vibration,
Magnetic particles and the toner 100 attached to the sleeve 22 are loosened
. In any case, it prevents the occurrence of uneven sweep and ghost images as in the case of a magnetic brush.
Can be stopped. Further, due to the vibration of the ears, the frictional contact between the magnetic particles 27 and the toner 28 is reduced.
Since the toner becomes active, the frictional charging of the toner 28 can be improved and fogging can be prevented.
A high developing efficiency is suitable for downsizing of the developing device. The magnetic pole in FIG.
Although b is changed to the developing pole 23c in FIG. 6, either one may be used in this example. The volume ratio of the magnetic particles 27 present in the developing section is (M / h) × (1 / ρ) × [
(C / (T + C)], where M is per unit area of the sleeve.
(G / cm) ^Two ), H is the height of the developing space
(Cm), ρ is the true density of the magnetic particles g / cm ^Three , C / (T + C) is the current on the sleeve
It is a weight ratio of the magnetic particles in the imaging agent. In the developing section defined above, the ratio of the toner to the magnetic particles is 4 to 40 times.
% Is preferred. As in the above embodiment, the alternating electric field is strong (change rate is large or
(Vpp is large), the ear separates from the sleeve 22 or its base and separates.
The removed magnetic particles 27 reciprocate in the space between the sleeve 22 and the photosensitive drum 1.
. Since the energy of this reciprocating motion is large, the effect of the above-mentioned vibration is further promoted.
Is done. The above behavior was confirmed by photographing at 8,000 frames / sec with a high-speed camera (manufactured by Hitachi, Ltd.). Surface of photosensitive drum 1 and sleeve 22
By reducing the gap between the surface and the surface, the contact pressure between the photosensitive drum 1 and the spike is increased, and vibration is reduced.
Even in the case where the pressure is reduced, the gap is large at the entrance and exit of the developing
Movement occurs, and the above-described effect is achieved. Conversely, the gap between the photosensitive drum 1 and the sleeve 22 is increased so that no magnetic field is applied.
In this state, the ear does not contact the photosensitive drum 1, but when applied, the distance
Is preferred. In FIG. 1, the surface of an aluminum sleeve having a diameter of 20 mm is
, Using an irregular sandblasting process with Alundum abrasive,
Then, a four-pole magnetized N pole and S pole were used alternately. Table with magnet 23
The maximum value of the surface magnetic flux density was about 900 gauss. The blade 24 is made of non-magnetic stainless steel having a thickness of 1.2 mm,
15 °. As the magnetic particles, a particle diameter of 70 to 5 whose surface is coated with a silicone resin
0 μ (250/350 mesh) ferrite (maximum magnetization 60 emu / g) was used. The above angles φ and θ _Two Was about 120 ° and 20-30 °. Also the above distance
L and l were 4 to 5 mm and 1.5 to 3 mm. As a non-magnetic toner, copper styrene / butadiene copolymer resin 100 parts is used.
Colloidal silicide is added to a toner powder having an average particle size of 10 μm comprising 5 parts of a talocyanine pigment.
When blue toner with 0.6% externally added was used,
A toner coating layer having a thickness of about 10 to 30 μm was obtained.
A magnetic particle layer of ~ 200μ was obtained. The toner adheres to the surface of each magnetic particle
I have. At this time, the total weight of the magnetic particles on the sleeve 22 and all the toners is about 2.43 ×
10 ^-2 g / cm ^Two Met. At this time, the weight ratio between the toner attached to the magnetic particles and the toner attached to the sleeve is about 2: 1.
Was. As described above, according to the present embodiment, high image density, high development efficiency, and fog
, Development with no ghost image, uneven sweep, and negative characteristics. The material of the sleeve 22 is not only aluminum but also brass and stainless steel.
Conductors, paper cylinders and synthetic resin cylinders can be used. Also, the surface of these cylinders
If it is subjected to conductive treatment or made of a conductor, it can function as a developing electrode.
Further, a conductive elastic body, for example, a conductive sponge is applied to the peripheral surface using a core roll.
It may be configured by winding. As for the magnetic pole 23b of the developing unit, the magnetic pole is arranged at the center of the developing unit in the embodiment.
May be offset from the center, and the developing section should be placed between the magnetic poles.
You may. In order to enhance fluidity, toner includes silica particles, for example, a transfer type image forming method.
Abrasive particles for polishing the surface of the photosensitive drum 3, which is a latent image holding member,
It may be added externally. A toner obtained by adding a small amount of magnetic particles to a toner may be used. sand
In other words, the magnetic particles are significantly weaker than the magnetic particles.
Can also be used. In order to prevent the ghost image phenomenon, the surface remaining on the sleeve 22 without being subjected to the development from the surface of the sleeve 22 that has turned back into the container 21 and rotated.
The image agent layer is scraped off once with a scraper means (not shown), and the scraped
Contact the magnetic layer with the magnetic layer to re-coat the developer.
Is also good. Detects the concentration of magnetic particles and toner and automatically compensates for toner according to this output.
A supply mechanism may be provided. The developing device of the present invention integrates the container 21, the sleeve 22, the blade 24 and the like.
Used developing device is the same as a normal developing device fixed to the image forming apparatus.
It can also be used. The developing device of the present invention is an electrostatic latent image carrier. Center O of photosensitive drum 1 _D Water passing through
Particularly suitable for arrangement in the second quadrant B or the third quadrant C with respect to the plane X and the vertical plane Y
ing. As described above, in the developing device of the present invention, the magnetic particle layer is formed by the movement of the magnetic particles.
Toner from the magnetic layer and rubs against the magnetic particles or the sleeve, the toner is subjected to triboelectric charging, and further, the toner content of the magnetic particle layer is automatically
However, it is maintained at a predetermined value. Generally, in a two-component developing device, the toner
Circulation of magnetic particles is very important for the charge application and maintenance of toner content
Although it is a factor, in order for the magnetic particle layer to circulate smoothly, the developer
The excess developer regulated by the material 24 has the starting point of magnetic particle circulation due to the action of gravity.
It is necessary to take a configuration to return naturally to the vicinity of the magnetic seal 31 which is
If it is necessary to arrange the developing devices in the second quadrant B and the third quadrant C due to the configuration,
The moving direction of the holding body 22 is opposite to the photosensitive drum 1, and
Due to inconvenience, sweeping unevenness tends to occur. However, by adopting the configuration of the present invention, it is prevented and a high-quality image is obtained.
It becomes possible. [Effect of the Invention] With the configuration of the present invention, the developing unit develops the image in the moving direction of the electrostatic latent image carrier.
Even in a configuration in which the agent rubs in the opposite direction, it is possible to provide a developing device having high density and high developing efficiency without uneven sweeping.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a first embodiment of the present invention, FIG. 2 is an explanatory view of a developer coating structure of the embodiment of FIG. 1, and FIG. 3 is a view of a second embodiment of the present invention. FIG. 4 is an explanatory view of the developing section of the present invention. 1 is an electrostatic latent image carrier (rotation direction of a), 22 is a developer carrier (rotation direction of b)
, 23c and 23b are magnetic poles for forming a magnetic field for fixing the developing section, 34 is an alternate electric field applying means, 27
Is magnetic particles, and 37 is toner particles.

Claims (1)

Claims: (1) A developer carrying member that forms a developing section with an electrostatic latent image carrier and carries and transports toner particles and magnetic particles is provided. In a developing device which performs development by moving the developer carrying member in the opposite direction to the electrostatic latent image carrier while contacting the ears, the volume ratio occupied by magnetic particles in the developing section is 1.5 to 30%, The toner particles are carried not only on the magnetic particles but also on the surface of the developer carrying member, and development is performed with both the toner particles carried on the magnetic particles and the toner particles carried on the developer carrying member. A developing device for forming an alternating electric field in the developing section.