JPS63225269A - Developing device - Google Patents

Abstract

PURPOSE:To decrease the pressure in the development section in a developing container on the upper stream of a nonmagnetic blade and to permit application of sufficient triboelectricity to toner particles by inclining the blade to the down stream side with respect to the moving direction of a developing sleeve. CONSTITUTION:The nonmagnetic blade 24 which is a member for controlling the coating amt. of a developer is inclined by phi deg. to the down stream side in the moving direction of the developing sleeve 22 and is fixed to the developing container 36. The developer consisting of magnetic particles 27 and toner particles 37 is attracted onto the sleeve 22 by the magnetic attraction force and electrostatic attraction force possessed by the developer. The developer conveyed near to the tip of the blade 24, therefore, passes a gap d2 between the tip of the blade 24 and the sleeve 22 and flows out to the development section or stagnates in the container 36 and rises successively along the front face 41 of the blade 24. Selection and electric charge improvement of the toner are thereby executed and the supply of the toner sufficiently applied with the triboelectricity to the development is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a two-component development type developing device that performs development using magnetic carrier particles and toner particles.

The present invention is a developing device that can be applied to various types of display devices for forming image records, printers, and facsimile electrophotographic devices.

(Background Art) The applicant of the present application previously explained that the conventional two-component development method is m f,
1 sun 9 inside the Φ rift
The present invention provides an apparatus that performs development by supplying only the fine toner.

In this method, magnetic particles are first introduced into the developer supply container, and the magnetic particles are adsorbed and retained as a magnetic particle layer (first layer) on the inner surface of the developer supply container of the rotating developing sleeve. was introduced and stored outside the magnetic particle layer (second layer) to perform development. (Unexamined Japanese Patent Publication No. 59
-204866, Japanese Unexamined Patent Publication No. 59-204867).

These devices bind magnetic particles in a developing container, and as the developing sleeve rotates, some of the trapped magnetic particles circulate on the sleeve. Through this circulation, replenishment toner is absorbed into the magnetic particles, and a thin layer of toner is formed on the sleeve. It formed a single layer. This is extremely important as it also discloses the basic structure of mixing and stirring magnetic particles and toner on a sleeve, and its effects were far superior to devices that did not adopt this basic structure. In particular, it was unparalleled in terms of equipment integration and miniaturization. However, even if a uniform thin layer of toner can be formed on the sleeve through this circulating action, if development is carried out over a long period of time or if some kind of impact is applied when the developing device is made removable from the main body of the image recording apparatus, It has been confirmed that this circulation effect becomes unstable, causing problems such as image deterioration. However, these inconveniences were minor in light of the unique features and advantages mentioned above.

Through numerous experiments, the applicant was able to resolve these disadvantages and actively supply magnetic carrier particles to the developing section2.
A developing device which produces great effects in a component developing device has been proposed in Japanese Patent Application No. 1988-204065 (filed on September 17, 1985).

According to these proposals, the developer forms a substantial backing state in the developer application amount regulating section. By stabilizing this backing state, it is possible to remove the toner lacking tribo and improve the charging of the toner, so that only toner that has been sufficiently tribo-charged can be conveyed to the developing section.

The developer in this bucking state is rearranged along the lines of magnetic force by a magnetic field provided slightly upstream of the regulating portion, thereby avoiding excessive pressure concentration.

[Problems to be Solved by the Invention] As described above, the developer in the regulating portion is always under constant pressure and is in a bucking state. Usually, in such a configuration, no deterioration of the developer is observed, especially as a result of the backing condition.

However, relatively soft toner such as light pressure fixing toner (
Toner that is sensitive to pressure may deteriorate slightly and may be fused to the drum. In addition, as the diameter of developing sleeves has recently become smaller, the surface area of the sleeve and the amount of magnetic particles in the regulating section (in other words, the surface area of magnetic particles that come into contact with toner) have decreased, so in order to apply effective triboelectricity to toner particles, According to the present invention, magnetic particles and toner particles In a developing device that develops a latent image using a developer in a developing section,
A developer container containing a developer having toner particles and magnetic particles, and a developing section facing a latent image carrier carrying a latent image and supplying toner particles to the latent image carrier; a developer carrying member that carries and transports the developer from the container to the developing section; a magnetic field generating means provided on the opposite side of the developer carrying member surface of the developer carrying member; a member for regulating the amount of magnetic particles and toner particles applied to the developer, the tip of the developer application amount regulating member being positioned in the developer on the upstream side in the direction of movement of the developer carrier; By arranging the regulating member so as to be inclined toward the downstream side in the movement direction, the load of the developer on the regulating portion is reduced.

FIG. 1 is a sectional view of a developing device according to an embodiment of the present invention.

The latent image carrier 1 is an insulated drum for electrostatic recording or a-8e.
, Cd s, ZnO,, OPC.

It is a photosensitive drum or photosensitive belt having a layer of photoconductive insulating material such as α-3i. The latent image carrier 1 is rotated in the direction of arrow a by a drive device (not shown). A developing sleeve 22 is in close proximity to or in contact with the latent image carrier 1, and is made of a non-magnetic material such as aluminum or 5OS316. The developing sleeve 22 has a right half-circumferential surface extending into the container 36 through a horizontally elongated opening formed in the lower left wall of the developing container 36 in the longitudinal direction of the container, and a left substantially half-circumferential surface exposed outside the container so as to be rotatably supported on a bearing. It is installed horizontally and is driven to rotate in the direction of the arrow.

Reference numeral 23 designates a fixed permanent magnet (magnet) as a fixed magnetic field generating means that is inserted into the developing sleeve 22 and positioned and maintained at the position and orientation shown in the figure. It remains fixed in its position.

This magnet 23 has an N-pole magnetic pole 23a, an S-pole magnetic pole 23b,
It has four magnetic poles: an N-pole magnetic pole 23c and an S-pole magnetic pole 23d. The magnet 23 may be an electromagnet instead of a permanent magnet.

Reference numeral 24 has a base fixed to the side wall of the container on the upper edge side of the opening of the developer supply device in which the developing sleeve 2 is disposed, and the tip side is made to protrude to the outside of the container 36 beyond the position of the upper edge of the opening, and extends along the longitudinal direction of the upper edge of the opening. The blade is a non-magnetic blade which serves as a developer regulating member and is made by bending, for example, 5uS316 into a dogleg shape in cross section.

27 is a magnetic particle with a particle size of 30 to 100 μm, preferably 40 to 80 μm, and a resistance value of 107 Ωcm or more, preferably 108 Ωcm or more, and ferrite particles (maximum magnetization 6
0 e mu / g) may be used.

37 is a non-magnetic developer toner.

Reference numeral 31 denotes a developing sleeve 22 on the inner surface of the lower part of the developing container in order to prevent leakage of magnetic particles 27 or non-magnetic toner particles 37 from the lower part of the developing container 36 in which the developing sleeve 22 is disposed.
A magnetic material placed opposite to the magnetic material, such as a plated iron plate. Magnetic body 31 and S polarity magnetic pole 23
A sealing effect that achieves collection of the magnetic particles 27 and prevention of leakage can be obtained by the magnetic field between the magnetic particles 27 and d.

Reference numeral 39 denotes a toner supplying member that supplies toner to a brush portion of magnetic particles formed by the fixed magnetic pole 23 in the developing sleeve 22. A rubber sheet is attached to a rotatably bearing plate, and the toner is swept over the lower surface of the developing container. transport. The toner supply member 39 is supplied with toner by a toner conveying member in a toner storage container 38 (not shown).

38 and 35 are a toner storage container and a magnetic particle storage container, respectively.

Reference numeral 40 denotes a sealing member for sealing the toner accumulated in the lower portion of the developer container 36, which is elastic and curved in the direction of rotation of the sleeve 22, and elastically presses the surface side of the sleeve 22. This sealing member tlO has an end on the downstream side in the rotational direction of the sleeve in a contact area with the sleeve so as to allow the developer to enter the inside of the container.

30 applies a voltage of the same polarity as the developer to the floating developer generated in the developing process to make it adhere to the photoreceptor side to prevent flying 1141.
It is a scattering prevention + M pole grip ~ Also, the S magnetic pole 23d is
It is a magnetic field generating means for magnetic sealing for forming a magnetic field from one side to the other between the magnetic member 31, and a portion thereof faces the magnetic member 31. The magnetic member 31 is located below the developing device at the substantial end of the developer accommodating portion of the developer container, and around the inside of the container, the collected magnetic carrier particles move to cause the developer on the sleeve surface to The toner particles located at the lower part of the container are taken in. Therefore, stable collection of magnetic particles has the effect of stabilizing the developing ability.

The magnetic member 31 has a "<" or rLJ shape, and can be made of a magnetic material that is not permanently magnetized, such as iron, or a non-magnetic material that is made weakly magnetic by deforming it. In addition, when using a magnet as the magnetic member 31, the flat surface 6
6 must have an N polarity that is different from the magnetism S of the magnet S.

In other words, the magnetic member 31 restrains the magnetic particles, prevents the loss of the magnetic particles, and facilitates collection of the magnetic particles, so that the toner particles in the developer container can be prevented from leaking from inside the container.

Furthermore, by arranging the magnetic pole 23d as described above, another favorable effect can be obtained in relation to the magnetic pole 23a. That is, due to the above-mentioned relationship between the bottom of the container 36 and the magnetic pole 23d, the magnetic brush inside the container 36 is Since the toner particles are not formed in a coarse state (compared to simply stagnant state), the amount of toner particles incorporated into the magnetic particles does not become excessive. cause the occurrence.

Note that this configuration is also effective when magnetic particles and non-magnetic or weakly magnetic toner are mixed in the developer container.

According to experiments, the distance between the developing sleeve and the magnetic member 31 is 2.
．． At 5 mm, the magnetic carrier particles were completely recovered, no leakage of toner particles was observed, and stable development was achieved. The presence of the surface 66 in this region means that the surface 66 can appropriately disperse the magnetic force of the magnetic pole 23d and can substantially increase the magnetic force in this region, thereby increasing the magnetic field sealing effect. Conceivable.

The distance d2 between the end of the non-magnetic blade 24 and the surface of the developing sleeve 22 is 50 to 800 μm, preferably 150 to 5 μm.
00 μm. If this distance is smaller than 50 μm, magnetic particles, which will be described later, will tend to clog between the gaps, causing unevenness in the developer layer, and it will not be possible to apply the developer necessary for good development, resulting in a developed image with a thin and uneven density. There are drawbacks that can only be obtained. If it is larger than 800 μm, the amount of developer applied onto the developing sleeve 22 increases, making it impossible to regulate the thickness of the developer layer to a predetermined value, and increasing the adhesion of magnetic particles to the latent image carrier (as well as increasing the amount of developer applied as described below). The drawback is that regulations are weakened, and toner triboelectricity is insufficient, making fogging more likely.

Even when the sleeve 22 is rotated in the direction indicated by the arrow, the magnetic particle layer prevents the sleeve 22 from absorbing the magnetic force and the binding force based on gravity.
Due to the balance with the conveyance force in the direction of movement, the movement slows down as it moves away from the sleeve surface (the magnetic particles can move a little at the top of the magnetic particle layer, but forms a stationary layer that is mostly immobile.Of course, the magnetic particles fall due to the influence of gravity) There is also.

Therefore, by appropriately selecting the arrangement positions of the magnetic poles 23a and 23d and the fluidity and magnetic properties of the magnetic particles 27, the closer the magnetic particle layer is to the sleeve, the more the magnetic particle layer is transported in the direction of the magnetic pole 23a, forming a moving layer. Due to the movement of the magnetic particles, the magnetic particle layer (first layer) takes in the toner from the toner layer (second layer), and the toner receives frictional electrification due to the sliding friction with the magnetic particles or the sleeve. It is transported to a developing area and subjected to development.

The movement of the magnetic particle layer is determined by the fluidity and magnetic force of the developer. When the toner content in the magnetic particles is low, the stationary layer becomes small and most of the magnetic particle layer moves quickly, and the toner from the toner layer becomes smaller. Incorporate. When the toner content is high, the static layer becomes large and the moving layer of magnetic particles cannot contact the layer of toner covered by this static layer and hardly takes up toner.

Therefore, some toner content is naturally maintained.

Next, the magnetic particle layer near and in the vicinity of the non-magnetic blade 24, which is a developer application amount regulating member, will be described. As described above, the non-magnetic blade 24 is fixed to the developer container 36 with an angle of φ0 toward the downstream side in the moving direction of the developer sleeve 22. The developer consisting of the magnetic particles 27 and toner particles 37 is attracted onto the developing sleeve 22 by the magnetic attraction force and electrostatic attraction force of the developer. As the developing sleeve 22 rotates in the direction of the arrow, the developer also moves in the same direction as the rotating direction of the developing sleeve. The developer that has been conveyed to the vicinity of the tip of the non-magnetic blade 24 passes through the gap d2 between the tip of the non-magnetic blade 24 and the developing sleeve 22 and flows out to the developing section (sometimes it remains in the developing container 36, There are two types of particles that rise along the upper surface 41 of the non-magnetic blade 24. Near the tip of the non-magnetic blade 24, as described above, the developer is dynamically exchanged, so the magnetic particles are separated from each other. They collide with each other and create a disturbed state.For this reason, triboelectricity is applied to the toner from the top of the magnetic particles or sleeve, and small triboelectricity is attached to the magnetic particles or sleeve with a weak force and is transported. The toner is separated from the magnetic particles or the sleeve.In other words, the toner is sorted and its charging is improved.

Therefore, toner to which sufficient triboelectricity is applied can be used for development.

Due to the above-mentioned regulation area, a stable amount of magnetic particles and sufficiently charged toner particles can be formed as a thin layer of developer on the surface of the developing sleeve. Therefore, the development effect in the development area 102 becomes stable. Then, an alternating electric field is formed in the developing section to transfer at least the L-ner particles carried on the surface of the developer carrying member to the electrostatic latent image carrying member. forming means, in the developing section, the magnetic particles of the developer conveyed to the developing section are larger than the volume of the space defined by the electrostatic latent image carrier and the developer carrying member. It has been confirmed that this has a great effect on developing methods and devices in which the volume ratio is 1.5% to 30%.

Next, the non-magnetic blade 24 remains in the developer container 36.
The developer moving along the upper surface 4.1 will be described. The developer that has climbed onto the upper surface 41 of the non-magnetic blade 24 is pushed upward by the developer that is sequentially conveyed as the developing sleeve 22 rotates. A steady state is reached when a certain amount of developer is on top of the upper surface 41 of the non-magnetic blade 24. That is, the pushing force of the developer and the gravity of the developer are in balance. Among the developer lumps on the top surface 41 of the non-magnetic blade that have reached a steady state, some of the developer particles located at a distance from the developing sleeve 22 fall again to the lower bottom of the developer container 36 due to their own weight. These developer lumps are not so-called strongly backed aggregates, but are arranged along the magnetic field formed by the north pole 23a and south pole 23b of the magnet in the developing sleeve 22, and are gradually pushed up from below. . therefore,
This mass of developer is subjected to only a certain amount of pressure while the developer particles are still movable with each other, and no excessive pressure is applied to the toner particles.

Returning to the regulating section at the tip of the non-magnetic blade 24, in this regulating section, a moderate pressure or bucking state is formed due to the presence of the above-mentioned softly backed mass of developer at the top. . This is because, if excessive pressure is applied to this regulating portion, the above-mentioned developer lump will be pushed upwards and this pressure can be released. In this way, the regulating section adjusts the pressure and stably maintains it at an appropriate pressure, making it possible to impart sufficient triboelectricity to the toner particles.

Now, the inclination angle φ of the non-magnetic blade 24 in the downstream direction is
The appropriate value varies depending on the contact angle α of the non-magnetic blade 24, but generally when α is positive, φ is 30°≦φ≦90°
(In the figure, the vertical line is 0 and the clockwise direction is positive.

) Desirably, 45°≦φ≦90° is good because the pressure applied to the toner particles is strong (and it is possible to provide sufficient triboelectric force).On the other hand, when α is negative, 300≦φ ≦60° is suitable for providing sufficient triboelectricity to the toner particles.

hl: -Jl- The angle θ formed by the peak position of the blade 24 and the peak position of the magnetic pole 23a of the magnet in the sleeve will be described. In order to make the magnetic particles stick to the upper surface 41 of the non-magnetic blade 24 and form a stable magnetic particle layer, the angle is preferably 5°≦θ≦20°. In addition, the magnetic pole 23a
The peak position is between the end of the non-magnetic blade 24 and the magnetic seal 3.
1 and the developing sleeve 22 from the center of the opening formed by
It is preferable to place it on the downstream side in the rotational direction. This is because when the peak position is set on the upstream side, there is a tendency that the magnetic particle layer is not stably formed on the upper part 41 of the non-magnetic blade 24.

The magnetic flux density of the magnetic pole 23a is preferably 600G or more, preferably 700G or more. This is because the applied state of the developer tends to be stable when the magnetic flux density of the cut magnetic pole is high in response to changes in the toner content of the magnetic particle layer. In particular, in the developing device of the present invention which does not have an automatic toner replenishing device to maintain toner content, it is preferable that the magnetic flux density be 800 G or more.

In FIG. 1, the magnetic pole 23c is a developing magnetic pole, and this developing magnetic pole is located in the developing area, and preferably has a magnetic flux density of 800 G or more in order to prevent magnetic particles from adhering to the latent image. .

It goes without saying that the present invention includes any combination of the above-mentioned configurations.

In any case, the present invention can provide high image quality that could not be obtained with conventional developing methods and devices, and has the excellent effect of making the developing device small and disposable.

The toner supply member 39 is located within the developer container 36 and is driven to rotate in the direction of arrow d in the vicinity of or in contact with the magnetic particle layer to supply toner 37 to the magnetic particle layer.

A toner storage container 38 for storing toner is arranged approximately horizontally adjacent to the developer container 36, and a toner transporting member (
(not shown) is provided.

The S magnetic pole 23b is a transport magnetic pole provided to prevent the developer layer uniformly applied by the non-magnetic blade 24 from being disturbed due to the large distance between the cut magnetic pole 23a and the developing magnetic pole 23c. The strength of the S magnetic pole 23b is preferably approximately equal to or slightly lower than that of the developing magnetic pole 23c so as not to disturb the developer layer. When a 20φ developing sleeve is used, if the distance between the cut magnetic pole and the developing magnetic pole is within 100° at the center angle of the sleeve, the developer layer on the sleeve will not be disturbed, but if it exceeds 100°, the developer The disorder of the layer is large (it is preferable to provide a transport pole in the middle).

The S magnetic pole 23d is a collection magnetic pole that collects the developer after development, and is arranged upstream of the tip of the magnetic seal 31 in the moving direction of the developing sleeve 22. The magnetic pole 23d is the magnetic seal 31
If it is placed downstream from the tip, a spike of magnetic particles is generated by the magnetic pole 23d near the toner intake port at the bottom of the developer container 36, and the toner is extremely easily taken in (as a result, frictional electrification is not sufficiently performed, resulting in fogging, etc.). This is likely to be the cause.

Here, the volume ratio of magnetic particles in the developing section will be explained. The "developing section" refers to the area from the sleeve 22 to the photosensitive drum 1.
This is the part to which toner is transferred or supplied. The "volume ratio" is the percentage of the volume occupied by the magnetic particles present in the developing area relative to the volume of the developing area. In the above-mentioned developing device, this volume ratio has an important influence, and it is highly preferred that it be between 1.5 and 30%, particularly between 2.6 and 26%.

If it is less than 1.5%, a decrease in the density of the developed image will be observed, a sleeve ghost will occur, a noticeable difference in density will occur between the area where the ears 51 are present and the area where the ears 51 are not present, and the concentration on the surface of the sleeve 22 will be reduced. This is undesirable in that the thickness of the developer layer formed is non-uniform throughout.

If it exceeds 30%, the degree of closure of the sleeve surface increases, which is undesirable because fogging may occur.

In particular, for the present invention, the above conditions listed as a preferable developing method are such that the image quality does not monotonically deteriorate or increase as the volume ratio increases or decreases;
Sufficient image density can be obtained within the range of 1.5%, and 3.
This is based on the fact that even if it exceeds 0%, the image quality deteriorates, and neither sleeve ghost nor fogging occurs within the range of the above-mentioned numerical value where the image quality is sufficient. The deterioration in image quality in the former case is thought to be due to negative characteristics, and in the latter case, the amount of magnetic particles present increases and the surface of the sleeve 22 is not released (
This is thought to occur because the amount of toner supplied from the surface of the sleeve 22 is significantly reduced.

On the other hand, if it is less than 1.5%, the reproducibility of line images is poor and the image quality and density are significantly lowered. On the other hand, if it exceeds 30%, there will be problems with the magnetic particles damaging the photosensitive drum surface and problems with transfer and fixing caused by the magnetic particles adhering as part of the image.

When the presence of magnetic particles is close to 1.5%, when reproducing a large-area uniform high-density image (solid black),
Since there are cases where partial development unevenness called ``developing unevenness'' occurs (under special circumstances, etc.), it is preferable to set a volume ratio that makes it difficult for these to occur.

This value indicates that the volume ratio of magnetic particles to the developing area is 2.6.
% or more, this range becomes a more preferable range. Also, if the presence of magnetic particles is close to 30%, there may be a delay in toner replenishment from the sleeve surface around the area where the ears of magnetic particles come into contact (at high development speeds, etc.), and scales may appear when solid black is reproduced. This may result in uneven density. As a reliable range for preventing this, it is more preferable that the volume ratio of the magnetic particles is 26% or less.

If the volume ratio is in the range of 1.5 to 30% (set to 4% in the example), the ears 51 are formed on the surface of the sleeve 22 in a preferable sparse state as shown in FIG.
Both the toner on the sleeve 22 and the tank are transferred to the photosensitive drum 1.
Since the toner 100 on the sleeve is also transferred by flight due to the alternating electric field, almost all the toner is in a state where it can be consumed for development, resulting in high development efficiency (
The proportion of toner present in the development section that can be consumed for development) and high image density can be obtained. Preferably,
A slight but strong vibration of the spike is caused, thereby causing magnetic particles and the toner 10 attached to the sleeve 22.
0 is loosened.

In any case, it is possible to prevent uneven sweeping and ghost images that occur in the case of magnetic brushes. Furthermore, the vibration of the ears activates the frictional contact between the magnetic particles 27 and the toner 28, thereby improving the frictional charging of the toner 28 and preventing the occurrence of fogging. Note that a high developing efficiency is suitable for downsizing the developing device. The magnetic pole in FIG. 2 is the first S pole 23b.
Although the developing pole 23c is shown in the figure, either one may be used in this example.

The volume ratio of the magnetic particles 27 existing in the developing section is (M/
b) It can be determined by X (1/ρ)X C (C/(T+C)). Here, M is the application amount (g/cr
rr), h is the height of the developing section space (cm), ρ is the true density of the magnetic particles g/c, and C/(T10) is the weight ratio of the magnetic particles in the developer on the sleeve.

Note that in the developing section defined above, the ratio of toner to magnetic particles is preferably 4 to 40% by weight. When the alternating electric field is strong (the rate of change is large or Vpp is large) as in the above embodiment, the ears separate from the sleeve 22 or from its base, and the separated magnetic particles 27 are placed between the sleeve 22 and the photosensitive drum 1. make a reciprocating motion in the space of Since the energy of this reciprocating motion is large, the effect of the vibration described above is further promoted.

The above behavior was observed using a high-speed camera (newly manufactured by Hitachi) with an accuracy of 8000.
This was confirmed by taking pictures at frames per second.

Even if the gap between the surface of the photosensitive drum 1 and the surface of the sleeve 22 is reduced to increase the contact pressure between the photosensitive drum 1 and the ears and to reduce vibration, the gaps are large at the entrance and exit sides of the developing section, so A vibration occurs, and the above-mentioned effects are reversed.

Conversely, it is preferable to make the gap between the photosensitive drum 1 and the sleeve 22 large (so that the ears do not contact the photosensitive drum 1 when no magnetic field is applied, but do come into contact when a magnetic field is applied).

In FIG. 2, the sleeve 22 is an aluminum sleeve with a diameter of 20 mm, the surface of which has been subjected to amorphous sandblasting using Alundum abrasive grains. I used something like the one shown in . The maximum value of the surface magnetic flux density due to the magnet 23 is approximately 9
00 Gauss.

The blade 24 was made of nonmagnetic stainless steel with a thickness of 1.2 mm, and the angle θ was 15°.

Further, α in FIG. 1 was 300, φ was 60°, and the length of the upper surface 41 of the nonmagnetic blade 24 was 15 mm.

As the magnetic particles, ferrite (maximum magnetization 60 emu/g) with a particle size of 70 to 50 μm (250/300 mesh) whose surface was coated with silicone resin was used.

The non-magnetic toner is a toner powder with an average particle size of 10μ consisting of 100 parts of styrene/butadiene copolymer resin and 5 parts of copper phthalocyanine pigment, and 0.6 parts of colloidal silica.
When using blue toner with external addition of %, sleeve 2
A toner coating layer with a thickness of 20 to 30 .mu.m was obtained on the surface of No. 2, and a magnetic particle layer of 200 to 300 .mu.m was further formed as an upper layer thereon. The toner is attached to the surface of each magnetic particle.

At this time, the total weight of the magnetic particles and all the toner on the sleeve 22 was about 2.43×10 −2 g/ctrr.

At this time, the weight ratio of the toner attached to the magnetic particles and the toner attached to the sleeve was about 2:1.

The magnetic particles are raised by the magnetic field generated by the magnetic pole 23b in the sleeve 22 in the developing area and its vicinity, resulting in maximum summary 1.
It formed a standing brush about 2 mm in diameter.

When the amount of charge was measured using the blow-off method, the amount of triboelectric charge of the toner on the sleeve and on the magnetic particles was +12 μC/g.
Met.

This developing device was installed in a PC-10 copying machine manufactured by Canon Inc., and the distance between the photosensitive drum 3 (made of an organic photosensitive material) and the surface of the sleeve 22 was set to 350 μm. When the volume ratio was determined under these conditions, it was approximately 10%. (h=350μ
mSM=2.43x10-”g/crd, ρ=5.
5g/l:rr? , T/ (T+C)=20.4%
). When developing was carried out using a bias power supply 4 with a frequency of 1600 Hz and a peak-to-peak value of 1300 V AC voltage and -300 V DC voltage superimposed,
A good blue image was obtained.

Further, when a solid black image was developed and the sleeve surface after development was observed, it was found that most of the toner attached to the magnetic particles and the toner on the sleeve were consumed, and development was performed with nearly 100% development efficiency.

As for development characteristics, there was no fog, and good development characteristics could be obtained.

Furthermore, when images were produced under the above development conditions using a non-magnetic toner (red) for light pressure fixing with an average particle size of 12 μm (toner for Canon PC-30), it was found that the image density was high and there was no fogging. No good images were obtained. Using the above-mentioned toner, a durability test of 0 images on approximately 5,000 sheets was conducted, and no drum fusion occurred.

As explained above, according to this embodiment, high image density,
It is possible to perform development with high development efficiency without fogging, ghost images, uneven sweeping, or negative characteristics. In addition, toner for light pressure fixing can also be used.

As the material of the sleeve 22, in addition to aluminum, conductive materials such as brass and stainless steel, paper tubes, and synthetic resin cylinders can be used. Furthermore, if the surfaces of these cylinders are subjected to conductive treatment or made of a conductive material, they can function as developing electrodes. Furthermore, a core roll may be used and a conductive elastic body, for example, a conductive sponge, may be wound around the circumferential surface of the core roll.

Regarding the magnetic pole 23b of the developing section, although the magnetic pole is arranged at the center of the developing section in the embodiment, it may be placed at a position shifted from the center, or the developing section may be arranged between the magnetic poles.

Silica particles may be externally added to the toner to improve fluidity, and abrasive particles may be added to the toner to polish the surface of the photosensitive drum 3, which is a latent image holding member in a transfer image forming method, for example. A toner containing a small amount of magnetic particles may also be used. That is, magnetic toner can also be used as long as it has significantly weaker magnetism than magnetic particles and can be tribocharged.

Further, in the embodiment of the present invention, a configuration is shown in which one magnetic pole is provided at the opening in the developer container, but a plurality of magnetic poles may be provided as transport poles.

In order to prevent the ghost image phenomenon, the surface of the sleeve 22 that has returned to the container 36 and has been rotated is removed without being subjected to development.
The developer layer remaining on the magnetic particle layer 2 may be once scraped off by a scraper means (not shown), and the scraped sleeve surface may be brought into contact with the magnetic particle layer to recoat the developer.

Further, in the present invention, an example in which the material of the blade is made non-magnetic is used, but it may be made magnetic. When a magnetic blade is used, it is possible to form a thick magnetic particle layer on the upper surface of the blade.

A mechanism may be provided that detects the concentration of magnetic particles and toner and automatically replenishes toner according to this output.

The developing device of the present invention can be used as a disposable type developing device that integrates a container 21, a sleeve 22, a blade 24, etc., or as a normal developing device fixed to an image forming apparatus.

[Example 2] Another example is shown in FIG. In FIG. 3, the blade is provided with a toner particle uptake control member 42 in the shape of a collar to cover the magnetic particle layer formed on the upper part of the non-magnetic blade 24. In FIG. This toner particle uptake control member 4
No. 2 does not apply any pressure to the magnetic particle layer on the upper part of the blade, and functions to prevent toner from entering from the outside, thereby promoting stabilization of toner rotation.

[Embodiment 4] FIG. 4 shows another embodiment. In FIG. 4, the above-mentioned magnetic blade is attached in parallel to the upper part of the non-magnetic blade 24 as an auxiliary means. This is to prevent the fact that when a magnetic plate is used as a regulating blade, the spikes of the developer applied thereon tend to become rough.

[Embodiment 5] FIG. 5 is an enlarged view of the vicinity of the tip of the non-magnetic blade 24 in FIG. 1. The difference from the embodiment shown in Fig. 1 is as follows.
This is the shape of the tip of the non-magnetic blade 24. The tip is a knife, so that magnetic particles can easily get onto the upper surface 41 of the blade 24.

By forming the tip of the blade 24 into a knife shape, it is possible to reduce the slight local pressure applied to the developer at the tip.

〔Effect of the invention〕

As explained above, by tilting the non-magnetic blade 24 toward the downstream side with respect to the direction of movement of the developing sleeve, it is possible to reduce the pressure in the regulating section in the developing container upstream of the blade, and toner particles can be reduced. It is possible to provide sufficient tripo.

As a result, it has become possible to realize a developing device with good image quality and no developer deterioration even for toners that are sensitive to pressure, such as toners for light pressure fixing such as capsule toners. In addition, in a simple two-component developing device that mixes toner and magnetic particles on a sleeve, it is possible to increase the amount of magnetic particles that hold magnetic force on the sleeve, making it possible to stabilize tripod attachment to the toner. Become. This is particularly effective when the outer dimensions of the sleeve are small, about 6 to 25 mm, because the amount of magnetic particles retained on the sleeve is small. Moreover, it is highly effective not only for pressure fixing toners but also for fine particle toners.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a developing device implementing the present invention, FIG. 2 is a schematic sectional view showing the state of developer in the developing section, and FIGS. 3 and 4 are other embodiments of the present invention, respectively. FIG. 5 is an enlarged sectional view of the vicinity of the tip of the blade. 1 is a latent image carrier, 22 is a developing sleeve, 23 is a magnet, 24 is a non-magnetic blade 27 is a magnetic particle, 37 is a toner particle, 39 is a toner supply member, 40 is a sealing member, 30 is a scattering prevention electrode, 36 is 41 is the upper surface of the non-magnetic blade; 42 is a toner intake regulating member; and 43 is an auxiliary magnetic plate.

Claims (2)

[Claims] (1) A developing device that develops a latent image using a developer having magnetic particles and toner particles in a developing section, comprising: a developer container containing a developer having toner particles and magnetic particles; and a developer container carrying a latent image. a developer carrying member that faces the latent image carrier and forms a developing section that supplies toner particles to the latent image carrier, and carries and conveys developer from the container to the developing section; a magnetic field generating means provided on the side opposite to the developer carrying surface of the carrying member; and a member regulating the amount of magnetic particles and toner particles applied on the developer carrying member surface; A developing device characterized in that a tip of a developer coating amount regulating member is positioned in the developer on an upstream side in the direction of movement of the developer carrier, and the regulating member is tilted toward the downstream side in the direction of movement. (2) The angle φ between the normal to the surface of the developer carrier and the developer coating amount regulating member at the position where the distance between the developer coating amount regulating member and the developer carrier is the shortest is 30°≦
2. The developing device according to claim 1, wherein the developer application amount regulating member is tilted downstream in the moving direction of the developer carrier so that φ≦90°.