JPS62234177A - Developing device - Google Patents

Abstract

PURPOSE:To obtain an excellent image free from uneven density from a developing device using a two-component developer by arranging a repulsive magnetic field in a developing sleeve and arranging a regulating means having a magnetic body on a position opposed to magnets. CONSTITUTION:When two magnets 7a, 7b having the same polarity are arranged in parallel in the developing sleeve to form a repulsive magnetic field, the magnetic developer carrier on the rotating developing sleeve 1 while being stick and held by magnetic force tries to stagnate on the upper part of the repulsive magnetic field. On the other hand, the line of magnetic force from a magnetic plate 2a of a blade 2 to be a regulating member is connected to a part of the line of magnetic force applied from the magnet 7a arranged on the upper side to stagnate the magnetic carrier. A non-magnetic plate 2b stick to the magnetic plate 2a has a function for turning the flows of the stagnated magnetic carrier and the developer upward. Consequently, the carrier in the developer is stagnated and efficiently removed and only toner is electrostatically stick to the rotating developing sleeve 1 and carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developing device suitable for a non-contact developing method, and in particular uses a two-component developer that has been improved to eliminate density unevenness during development. The present invention relates to a developing device.

[Conventional technology]

Conventional non-contact developing methods include (1) U.S. Patent No. 3
．． 893. = Publication No. 18, (2) JP-A-55-18
Publication No. 656-55-18G59, (3) JP-A-Sho GO-
A method disclosed in Japanese Patent No. 42767 is known.

In the development area, the toner is caused to fly by an alternating electric field while keeping the photosensitive layer and the toner layer in non-contact.
This is the developing method used.

In the methods described in (1) and (2) above, a -component developer is used, and after a 0 layer of charged toner is uniformly provided on the developing sleeve, which is a toner transport and support means, the developing sleeve The toner is made to fly by applying an alternating current bias voltage to the toner.

In the method described in (3) above, only the toner is passed through the two-component developer consisting of carrier and toner by the magnetic force and gravity created by the arrangement of magnetic poles in the developing sleeve.

The key to realizing a one-component non-contact development method is to form a thin layer of only charged toner. For this reason, the above (1)
In contrast to 2), in the method described in the publication, magnetic toner is used and a regulating member of one layer of toner having a magnetic material is used to prevent this. It has been realized and commercialized.

-) Secondary (:3) The method described in (3) is realized by using a developer consisting of a carrier and a toner and by devising the arrangement of magnets.

[Problem that the invention seeks to solve]

The method described in subsections (1) and (2) escapes from the constraints of using magnetic toner, and the magnetic substance contained in the toner... It has the disadvantage that it is not possible to obtain vivid color toner images. Further, although the method described in (3) above does not have the above drawbacks, it is limited by the shape of the developing device because it uses not only magnetic force but also gravity as a force to prevent the passage of carriers.
There is a drawback 3 that the carrier tends to pass through the toner regulating section as the developing sleeve rotates during high-speed development.

When non-magnetic component developers are used, white streaks as described below often occur.

FIG. 5 is an explanatory diagram showing a state in which white streaks occur. An elastic rubber blade 2, which is a toner thickness regulating member, is lightly pressed around the developing sleeve 1, which is a developer conveying member. On the other hand, -component developers tend to aggregate, particularly at high temperatures and high humidity.

This aggregated toner gets clogged in the gap between the developing sleeve 1 and the blade 2, and the thin supply of toner is cut off at the clogged area, resulting in white streaks. When developing with such toner on the circumferential surface of the developing tube IJ, it causes density unevenness on the image, and the amount of charge on the toner is generally insufficient. .

In order to solve this problem, a member 3 for cleaning the blade 2 is provided, and the toner aggregates. A method for preventing and destroying agglomerated toner, or a method disclosed in JP-A-Sho (additional number 127) described in (3) above.
(Although methods using carriers as described in Publication No. 57 have been proposed, they are still insufficient and are not definitive methods.

It is an object of the present invention to solve the above-mentioned difficulties in forming a thin layer of charged toner and to provide a developing device 1f that obtains a thin layer of toner in a good charged state and performs development.

〔problem? Means to solve]

The above object is to provide a developing device that uses a two-component developer consisting of a magnetic carrier and toner, in which a magnet is provided in the developing sleeve to form a repulsive magnetic field, and a regulating means having a magnetic material is arranged at a position facing the magnet. This is achieved by a developing device characterized by the following. As a specific structure for forming a single layer of toner, in a developing device using a two-component developer consisting of a magnetic layer and toner, a magnet arranged so that magnetic poles of the same polarity are lined up in a developing sleeve is used to form a single layer of toner. A magnetic field having a two-peak distribution of magnetic flux density is formed on the developer carrying surface of the sleeve, and a regulating means having a magnetic body 2 is disposed between the magnets where the magnetic flux density of the magnetic field is coarse, thereby controlling the development. The toner is allowed to pass between the sleeve and the regulating means, while the magnetic carrier is prevented from passing.

[Effect]

Next, the operation will be explained with reference to FIGS. 1 and 2.

In the present invention, a repulsive magnetic field is created by providing bipolar magnets as shown in FIG. 1 in close proximity to each other in a rotating non-magnetic developing sleeve l. Specifically, the magnetic flux distribution is made to have a two-peak distribution with two peaks of the same polarity, and the magnetic flux distribution, which is a regulating member, is placed near the coarse magnetic flux density between the peaks of the magnetic flux distribution, facing the developing sleeve l. It has two blades consisting of a body.

When magnets 7 a and 7 b of the same polarity are placed adjacent to each other as shown in FIG. 2, a two-peak distribution of magnetic force is obtained as shown in the figure. When the developing sleeve l is stopped, the magnetic developer has two peaks due to the force according to the magnetic field. A portion where no magnetic developer is present is created in the center.

When the Q sleeve 1 is working, the magnetic developer is distributed according to changes in the magnetic field strength, but in the center between the peaks of the magnetic field strength, the ears formed by the magnetic developer are The density is small near the developing sleeve,
” It is shaped like a nigga. This means that the magnetic developer tries to stay upstream of the moving developing sleeve 1, but due to the conveyance force based on the movement of the developing sleeve 1, some of it is repelled at the midpoint between the peaks of the magnetic field strength. This means that it exceeds the magnetic field area.

In addition to the developer retention effect caused by the repelling magnetic field thus formed, the present invention further improves the retention effect 3 by making at least a part of the regulating means facing the developing sleeve a magnetic material.
By adding it, it prevents the passage of the developer consisting of magnetic carrier and toner. Furthermore, the passage of the magnetic carrier in the developer is selectively carried out.

〔Example〕

Figure 11 is a sectional view of a main part showing a third embodiment of the present invention.

Two same polarity magnets 7a, 7b can be formed. The magnetic developer adhered and held by magnetic force on the developing sleeve l rotated by this magnetic field and conveyed tends to stay upstream of the repelling magnetic field.

- - The magnetic plate 2a of the blade 2, which is the above-mentioned regulating member, is lightly pressed against the developing sleeve l, or facing the developing sleeve, a slight four-ridge is formed near the center of the repulsive magnetic field and slightly upstream. It is set apart. This magnetic plate 2
The magnetic field generated by a further stabilizes the developer retention fan.

In FIG. 1, a magnetic plate 2 is placed on a non-magnetic plate 2b as a blade 2.
An example using a2 pasted together? It shows. Magnetic plate 2a provided slightly upstream from the center between homopolar magnets
The lines of magnetic force from the magnet 7a are connected to a part of the lines of magnetic force from the magnet 7a provided on the upstream side, and the magnetic carriers are retained therein. Furthermore, the non-magnetic plate 2b bonded to the magnetic plate 2a has a function of directing the flow of the retained magnetic carrier and developer upward.

In this way, what about the carrier in the developer? (I! Only the toner is electrostatically adhered to the rotating developing sleeve l, which is efficiently removed and transported, and then comes out.

FIG. 3 shows another embodiment of the present invention in which a cylindrical magnetic rod 4 is rotatably installed in the regulating section. The magnetic rod 4 is installed in the upstream side of the center of the repulsion magnetic field, and the lines of magnetic force from the magnetic rod 4 are connected to the magnet 7a installed on the first-stream side.
It is connected to a part of the magnetic field lines from the magnetic field, and retains the magnetic carriers. Moreover, since the magnetic body ti 1 is rotated, it has the effect of moving the retained carriers to the magnetic body rod 4 +JXJ and removing and carrying them out from the regulating part. Note that n is a blade for removing toner and magnetic carrier attached to the rotating magnetic body 4, and a sponge C is attached to the tip of the blade to remove toner and magnetic carrier attached to the rotating magnetic body 4.
Contacts one circumferential surface.

In this way, the carrier C in the developer is efficiently removed, and only the toner '2' electrostatically adheres to the rotating developing sleeve 1 and is conveyed out.

Note that in the magnetic flux distribution shown in FIG. 2, it is preferable that the six values for the two peak values be within the range of 20% to 95%. According to experiments, the best result 3 could be obtained at about 70%. In addition, as shown in FIGS. 3 and 4, the essence of the present invention is to install magnetic poles with the same symbol in close proximity to each other, and other than the case where two magnets 3 are installed as shown in FIG. This also includes, for example, a case in which a concave shape is removed from the center of the magnet and a single magnet is installed in which magnetic poles of the same sign are adjacent to each other.

The average particle diameter of the magnetic carrier particles used in the electrostatic image developing apparatus described above is 20 to 200 .mu.m, particularly preferably 30 to 100 .mu.m, and the average particle diameter of the toner particles is preferably m.mu.In or less.

In the conventional two-component magnetic brush development method, the toner 3 is charged by friction with the carrier, and the .ji?
The toner was sucked in by the coulomb with the mold part. Therefore, in order to have sufficient charge 3 for development with toner, developer particles -E? There was a limit to how detailed it could be.

However, in this embodiment, there is no apex as described above even in the case of toner particles.

In the embodiment of the present invention, since an oscillating electric field is used to develop the latent image, the toner particles vibrate between the developing sleeve (2) and the image carrier 3. Even if there is no sufficient contact between the toner and the image carrier 3, an "if" visual image is formed by the toner on the image carrier 3.

In order to prevent fogging, the developer layer Q formed in the developing area is preferably smaller than the distance between the image carrier and the sleeve. Further, the moving speed of the developer is preferably the same or faster as the developer moves in the same direction or in the opposite direction to the image carrier, but is not limited thereto.

Therefore, it has become possible to use fine toner particles that cannot be used in conventional magnetic brush development methods.

In the regulating section, the toner is attached to the developing sleeve and moves, while the carrier needs to be stopped by magnetic force, and the particle size of the carrier particles used in the present invention is 2.
If it is less than 0 μm, the magnetization will be too weak, and if it exceeds 200 μm, the toner layer formed on the developing sleeve will become uneven and the image will not be improved, and even if a small amount of carrier slips through the regulating part, breakage or discharge will occur. high voltage cannot be applied.

Practical - Preferred carrier particle size range is 30-100μ
It is m. If the magnetization of the carrier is 3Q emu/g or more, a sufficient magnetic east binding force can be generated. The magnetic field on the developing sleeve is preferably 400 to 1500 gauss. The strength of magnetization of the carrier explained above is the strength of magnetization of the carrier at the peak of the magnetic field on the sleeve in the regulating portion. On the other hand, the toner particle size is 0.5 μm
If the thickness is below 20 μm, it becomes difficult to peel off from the carrier even if vibration is applied. If it exceeds the limit, the image resolution will decrease. From this point of view, the toner particle diameter is preferably 0.5 to 20 μm, and more preferably 1 to 20 μm. Also, the average charging of the toner at this time is 3 to 300 μc/g.
is preferable, and especially G: 10-100 μc/g is preferable.

Incidentally, since a direct current voltage to prevent fogging and a vibrating electric field to vibrate the toner are applied between the image carrier 3 and the developing sleeve l, the spacing between them becomes a problem. If this distance is made too narrow, electric discharge will occur between the two, damaging the image carrier 2 and interfering with the transport of toner passing between the two. On the other hand, if the distance between the two is too wide, the opposing electrode effect will decrease.
Recording of sufficient development density is not recorded, and edge effect 1 becomes high. According to experiments, desirable results were obtained when the distance between the two was set to 2000 μm or less, particularly between several tens of μm and 1000 μm.

Another embodiment 3 is shown in FIG. 1B. l is a non-magnetic cylindrical sleeve that rotates in the direction of the arrow, and has an outer diameter of 20 mt.
xl and the rotational speed is 100 strokes. In this embodiment, the linear velocity of the outer circumference of the developing sleeve 1 is set to be the same as the circumferential velocity of the image bearing book 3. The image carrier 3 is made by vapor depositing Se on the outer periphery of the drum. The potential formed by image exposure is
The voltage on the black background is 800V, and the voltage on the white background is 50V.

Here, a blade 2 according to the present invention as shown in FIG. 1 is provided on the upstream side of the developing sleeve l to the developing area. rs n!L F't l→n riwm
t, = IQ. Further, a developing area A is formed by maintaining a distance of 1 ft 0.3 vx between the circumferential surface of the image carrier 3 and the circumferential surface of the developing device. It is preferable that the surface of the developing sleeve is uneven with an I depth of 5 to 20 μm.

Inside the developing sleeve 1 are two fixed permanent magnets, including a permanent magnet 6 for transporting the developer. Also blade 2
There are S-pole magnets 7a inside the developing sleeve l on both sides.
, 7b are arranged at a central angle θ=po.

The magnetic flux density on the circumferential surface of the developing sleeve 1 of the magnets 7a and 7b is designed to have a two-peak distribution.
00 gauss, and 400 gauss in the valley. The tip of the magnetic part of blade 2 is -5 close to the flowing mountain part.
It is located at a magnetic flux density of 0.00 gauss.

The developer used in this example and 1. 7 average particle diameter 8゜tt
An insulating carrier coated with resin-coated spherical ferrite particles of 517. The toner and the insulating toner having an average particle diameter of 10 μm were stocked in the developer container 5 at a ratio of 1:1 to 10:1, and development 3 was performed. The band surface W of the toner is -2(l ttc/cr
Met. The developer stored in the developer storage portion 5 passes over the magnet 7a'h7b disposed facing the blade 2 as the developing sleeve l rotates. Here, the passage of the carrier is regulated by the blade 2, and the carrier is conveyed to the development area A with only toner attached to the sleeve L, and the latent image on the image carrier 3 is developed. Here, the developing bias voltage applied to the developing sleeve 1 is C200V, A, C1.
An alternating current bias voltage of 000 V, 21 (1-1z) is applied in a superimposed manner to perform development. The toner consumed by the development is replenished in the developer storage section 5, and the rotation of the stirring plate 8 causes the carrier and toner to be mixed. Frictional electrification is performed based on uniform stirring and agitation.

In this embodiment, in order to continue to perform good development even when continuous copying is performed and to keep the toner formed on the developing sleeve 1 more stable, it is necessary to remove the toner remaining on the sleeve 1 after development. It is best to remove it once. If residual toner is left on the developing sleeve 1, the difference between the undeveloped area on the developing sleeve and the developed area where no toner remains will be the difference between the remaining toner and the developed area, even if toner is newly added to the developing sleeve. Even if it is supplied, it often appears as a density difference in the image. Furthermore, as the toner gradually accumulates on the developing sleeve, the quality of the developed image gradually deteriorates. For this reason, it is necessary to scrape off the residual toner. This scraping means can be a Mylar plate, a phosphor bronze plate, a brush, or a sponge roller, etc. at the position after the development is completed on the developing sleeve lI'7i! There is a way to make it come into contact with a surface.

In the embodiment shown in FIG. 4, the sponge roller 9yi:
While rotating in the direction of the arrow, the developing sleeve 1 is brought into contact with the developing sleeve 1 on the upstream side of the developer accommodating portion 5 to scrape off residual toner, thereby preventing the occurrence of the above-mentioned density unevenness.

In the present embodiment described above, the carrier and toner are separated by the blade 2, and transported to the development area A with only the toner attached to the circumferential surface of the developing sleeve 1. It was confirmed that good images could be continuously obtained after development.

Note that when an integrated GOO Gauss magnet was used instead of the magnets 7a and 7b in FIG. 4, the carrier easily passed through, and the same developer regulating effect e as described above could not be achieved. Further, as a bias voltage applied to the developing sleeve 1, the DC bias voltage for preventing fogging is usually kept at a higher potential than the non-image area.
A voltage of ~500 V is applied and the developer D7il- to vibrate at 100-10 K 1z, preferably 1
An alternating current with a frequency of ~5 t<t-tz is used. The DC voltage may be smaller than this if the toner has magnetism. Naturally, when performing reversal development, a DC voltage higher than this is applied. The voltage value of AC is
Although it depends on the frequency, the higher the frequency, the more the developer is vibrated, but on the other hand, fogging and discharge are more likely to occur. As the frequency increases, the amount of developer cannot follow this change, and there is a tendency for the development to 0 degrees and the sharpness to decrease, resulting in a decrease in image quality.

As the carrier particles in the present invention, carrier particles that are the same as conventional magnetic carrier particles can be used in terms of average particle size 3. fffJ, iron, chrome, leek'l"
/L/ , :l Metals such as Hult, or their compounds and alloys, ferromagnetic materials such as triiron tetroxide, γ-ferric oxide, chromium dioxide, manganese oxide, ferrite, manganese-copper alloy Or particles of paramagnetic material, or the surface of these particles 3 Styrene resin, vinyl resin, ethylene printing press, rosin modified abrasive resin, acrylic resin, polyamide printing press, epoxy resin, polyester resin, etc. Insulating particles coated with a resin or a fatty acid wax such as balditic acid or stearic acid can be used.

However, among these, insulating magnetic particles having a resistivity of 10' Ωm or more, particularly preferably IQ+3 Ωm or more are particularly preferred. If the resistivity is low, when a bias voltage is applied to the developer transport carrier, charge is injected into the carrier particles and C1
Problems arise such as easy leakage from the developing container, insufficient application of bias voltage, and breakdown of carriers that have passed through the regulating section in the developing area.

In addition, the resistivity is determined by placing the particles in a container with a cross section of 0.50 ci and pinging in the evening, then applying 1k on the packed particles.
Hang the front claw of g/c+yf, and place 1 between the front claw and the bottom electrode.
This value is obtained by reading the current value when a voltage that generates an electric field of 000 V/Crn is applied.

Further, the insulating particles are not limited to those in which a coating layer of resin or the like is provided on the surface of magnetic particles, but may be those in which magnetic particles are dispersed in resin.

The carrier particles as described above are produced in the same manner as conventional carrier particles, and are used in the present invention after being selected for the lower average particle size by a conventionally known average particle size selection means.

Even if the toner particles in the present invention are conventional non-magnetic or magnetic toner particles? Toner particles sorted by an average particle size sorting means can be used. and,
It is preferable that the toner particles are magnetic particles containing fine magnetic particles, and it is particularly preferable that the amount of fine magnetic particles does not exceed 30 wt%. When the toner particles contain magnetic particles, the toner particles are transferred to the developer transport carrier 2.
The shadow of the magnetic force of the magnet contained in g? Because you will receive it,
The ability to form a single layer of toner is further improved, fogging is prevented, and scattering of toner particles is also less likely to occur. However, if the amount of magnetic material contained is too large, the magnetic force between the carrier particles and the carrier particles becomes too strong, and the toner layer formed on the sleeve becomes thinner, making it impossible to obtain a sufficient developing density. In addition, fine magnetic particles appear on the surface of the toner particles, making it difficult to control triboelectric charging and making the toner particles more likely to be damaged.
They tend to aggregate with carrier particles.

The toner particles described above use fine particles made of resin as described for the carrier particles, and a coloring component such as carbon and, if necessary, a charge control agent, etc. 3 are added thereto.
It can be produced by a method similar to a conventionally known method for producing toner particles.

The developer in the present invention is a mixture of carrier particles and toner particles as described above in the same ratio as in conventional two-component developers, but if necessary, a fluid sliding mechanism of the particles is added. A fluidizing agent for cleaning the surface of the image carrier, a cleaning agent for cleaning the surface of the image carrier, and the like are mixed.

As the fluidizing agent, Coro・R Dull Silica, Silicon Face, Kinmishiki, or nonionic surfactant can be used.As the cleaning agent, surface active agent such as fatty acid metal salt, organic group-substituted silicon, or fluorine can be used. Agents, etc. can be used.

Further, it is preferable that the blade 2 and the magnetic rod 4 be at the same potential as the developing sleeve, or be floating.

Furthermore, the present invention is applicable not only to forming toner m3 on the developing sleeve, but also when forming a thin layer of a two-component developer using small particle diameter carrier 2, for example, in the case of forming a thin layer of a two-component developer using
It can also be used to form a thin layer of developer in the two-component non-contact development method shown in No.

〔Effect of the invention〕

When using the developing device described above, it is possible to use two-component development to form a uniform and stable thin layer of sufficiently charged toner on the developing sleeve, and moreover, it is possible to form a uniform and stable thin layer of only sufficiently charged toner on the developing sleeve. A good image with no white streaks or μ tones is obtained. This has the effect of resolving the difficulty of installation accuracy.Also, since a stable thin layer of toner can be obtained on the developing sleeve, a developing device capable of obtaining good images even by non-contact development has been provided.

[Brief explanation of drawings]

Is Fig. 1 an embodiment of the present invention? 2 is a diagram for explaining the repulsion magnetic field, FIG. 3 is a sectional view of the main part showing an embodiment of the pond of the present invention, and FIG. 4 is still another embodiment 3 of the present invention.
FIG. 5, which is a sectional view of the main part shown, is an explanatory diagram of the occurrence of white streaks. 1...Developing sleeve 2...Blade 3...Image carrier 4...Magnetic rod 5...Toner storage section 6... ... Permanent magnet 7 ... Same polarity magnet 8 ...
Stirring plate 9...Sponge roller 1()...
...Developer'!゛...Toner C...
...Career applicant Konishiroku Photo Industry Co., Ltd. Figure 1 7b74 Figure 2 7b 7 1 Figure 3 Figure 5

Claims (4)

[Claims] (1) In a developing device that uses a two-component developer consisting of a magnetic carrier and toner, a magnet that forms a repulsive magnetic field is provided in the developing sleeve, and a regulating means having a magnetic material is arranged at a position facing the magnet. A developing device characterized by: (2) The magnetic carrier has an average particle size of 20 to 200 μm
The developing device according to claim 1, characterized in that the developing device is located between. (3) The developing device according to claim 1 or 2, wherein the magnetic carrier has a density of 30 emu/g or more. (4) The developing device according to any one of claims 1 to 3, wherein the magnetic body located opposite to the magnet in the developing sleeve is installed upstream of the repulsive magnetic field. Device.