JPS62234175A - 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 making toner pass by cooperation based upon magnets arranged in a developing sleeve and a magnetic body to be rotated oppositely to the developing sleeve and blocking the passage of a magnetic carrier. CONSTITUTION:A sponge 2C is fitted to the tip of a blade 2 for blocking the passage of the developer on the magnetic body 4 and abutted against the periphery of the magnetic body 4. When the sleeve 1 for carrying the developer in a magnetic field formed by the magnets 7 and the magnetic body 4 is moved in the arrow (a) direction, toner T is separated from the carrier C in a regulating area and a toner layer is formed on the sleeve 1. When the magnetic body 4 is rotated as shown by the arrow (b), carrying force reversed from that of the sleeve 1 is applied to the developer and the passage of the carrier C in the developer can be surely blocked in corporation with restriction force based upon the magnetic field.

Description

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

[Conventional technology]

Conventional non-contact developing method and 1. (1) U.S. Patent No. 3.893.418, (2) Japanese Unexamined Patent Publication No. 1986-186
56-18659, (3) JP-A-60-4276
A method disclosed in Publication No. 7 is known.

These are development methods in which development is carried out by causing toner to fly using an alternating electric field while keeping the photosensitive layer and toner layer in non-contact in the development area.

-1- In the method described in (1) and (2),
- This is a method in which component developers are placed in three uniform layers of charged toner on a developing sleeve, which is a toner transport and support means, and then the toner is made to fly by applying an AC bias electric current to the developing sleeve. There are 1.

1: In the method described in item (J), 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. -Component The key to realizing the non-contact development method is to form an R layer of only charged toner. Therefore, in contrast to (1) above, in the method described in the publication (2), a magnetic toner is used as the toner, and a toner layer thickness regulating member containing a magnetic material is used to realize this and commercialize the toner.

In the method described in (3) above, a developer consisting of a carrier and a toner is mixed and the magnet arrangement is devised.

[Problem that the invention seeks to solve]

It is difficult for the methods described in (1) and (2) above to avoid the limitations of using magnetic toner, and because the magnetic material contained in the toner is generally black, vivid color images can be formed. have the disadvantage of not being able to
In addition, although the method described in (3) above does not have the above-mentioned drawbacks, it uses not only magnetic force but also claw force as a force for blocking the passage of carriers, and is therefore limited by the J-shape of the developing device. This has the disadvantage that the carrier tends to pass through the regulating portion as the developing sleeve rotates during development.

When a non-magnetic component developer is used, the white streaks described below often occur. FIG. 6 is an explanatory diagram showing the conditions in which white streaks occur. An elastic rubber blade 2, which is a toner m/thickness ff111 member, is lightly pressed around the circumference of a developing sleeve 1, which is a developer conveying member. On the other hand, -component developers tend to aggregate, especially at high temperatures and high humidity. water.

This aggregated toner gets clogged in the gap between the developing sleeve 1 and the blade 2, and at the clogged location, toner supply is cut off and a white streak L is generated, and the circumferential surface of the developing strip IJ-pu 1 is in such a state of toner. When developing with 1:, this causes density unevenness in the image ((G!, 1:), and the toner is generally insufficiently charged.

In order to solve this problem, a member for cleaning the blade 2 is provided, a method for preventing toner aggregation and destroying the agglomerated toner, or a method described in JP-A-60-4276 described in (3) above.
In Publication No. 7, a method using defeated carriers was proposed.
There are C methods, but they are still insufficient and not definitive methods.

The present invention is a charged toner! It is an object of the present invention to provide a developing device which eliminates the various drawbacks mentioned above in forming the i-layer, obtains an R layer of toner in a good charging state, and performs development.

[Means for solving problems]

The secondary purpose is to develop a developing device a using a two-component developer consisting of a magnetic carrier and a toner, in which a magnet a placed in a developing sleeve and a rotating magnetic body positioned opposite the developing sleeve are used. Owned by both vjJ11111 +
Toner by 1'7? This is achieved by a developing device characterized by having a toner presence forming means that blocks the passage of the magnetic carrier while allowing the toner to pass therethrough.

[Effect]

Next, the operation will be explained with reference to FIGS. 2 and 3. Second
As shown in the drawings and FIG. 3, when the blade 2 or the magnetic material 4, which is a regulating member made of a magnetic material, is placed opposite to the fixed magnet 7 in the developing sleeve l, the magnetic force distribution as shown in the drawings is obtained.

When the developing sleeve is stopped, the magnetic developer in a mixed state with the magnetic carrier and toner creates a part in the center where the magnetic developer stays due to the magnetic force caused by the magnetic field. When the developing sleeve 1 is moving in the direction indicated by arrow A, the magnetic developer tends to stay in the restricted product area, but some of the carriers end up exceeding this area due to the conveyance force.

What is shown in FIG. 3 is a toner layer forming apparatus according to the present invention that solves this problem. By moving the sleeve 1 that conveys the developer in the direction of arrow A within the magnetic field formed by the magnet 7 and the magnetic body 4 as shown in the figure, the toner '1' and the carrier C are separated in the regulation area, and the sleeve A toner layer is formed on l. and magnetic material 4
By rotating the sleeve as shown by the arrow, a conveying force is applied to the developer in the direction opposite to that of the sleeve 1, which, in combination with the restraining force caused by the magnetic field, ensures that the carrier C in the developer passes through the sleeve 1 in one direction. This is how it was done. Note that 2 is a blade that prevents the developer from passing through the magnetic body 4, and has a sponge 2C attached to its tip and comes into contact with the circumferential surface of the magnetic body 4.

〔Example〕

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention. Permanent magnets 6 and 7 are fixedly placed inside the cylindrical developing sleeve 1 made of a non-magnetic material. A magnetic field as shown in Figure 3 is formed. Due to this magnetic field, the magnetic developer that has been conveyed by magnetic force on the developing sleeve is retained in the regulating section. Moreover, since the magnetic body 4 rotates in the direction shown in the figure, the carrier C that is about to pass through the regulating section is 1f
lll +l-, and only toner T is on the developing sleeve! A toner layer is formed on the sleeve 11 by electrostatically adhering to the sleeve 11 and being conveyed. As a result of the rotation of the sleeve l and the image carrier 3 as shown by the arrows, they both move in the same direction in the developing area A. Then, in the development area A, due to the power source beauty,
As shown later, an alternating voltage having a DC component is applied. The magnet 6 is a magnet that exerts a force of 77 to convey the developer 10 toward the developer regulating section 4 .

In the conventional two-component magnetic brush development method, the toner is charged by friction with the carrier, and the toner is attracted by Coulomb force with the charged portion of the image carrier 1. Therefore, in order to have enough charge for development with toner,
There was a limit to how fine the developer particles could be.

However, in this embodiment, even if the toner is used as fine particles, the above-mentioned problems do not arise.

In the embodiment of the present invention, since an oscillating electric field is used to develop the latent image, the toner particles move in an EW manner between the speed I and the image carrier 3, unlike the conventional magnetic brush development method. Even if the developer and the image carrier 3 do not come into contact with each other, a visible image is formed on the image carrier 3 by the toner.

In order to prevent fogging, the thickness of the developer layer 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, the use of fine toner particles, which cannot be used in conventional magnetic brush development methods, has resulted in +TJ performance.

In the regulating section, the toner adheres 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 20.
If it is less than 200 μm, the magnetization will be too weak, and if it exceeds 200 μm, the toner layer formed on the developing sleeve will become non-uniform and the image will not be improved, and even if a small amount of carrier rubs against the regulating part, breakdown or discharge will occur. This happens easily and high voltage cannot be applied.

Practically preferred carrier particle size range is I to 100μ.
It is m. If the magnetization of the developer is north of 3Q emu/g, a sufficient magnetic binding force can be generated.

The magnetic field on the developing sleeve is 400-1500 gauss
is preferred. On the other hand, if the toner particle diameter is less than 0.5 μm, it will be difficult to peel off from the carrier or developing sleeve even if vibration is applied, and if it exceeds 20 μm, the resolution of the image 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 uniform charge of the toner at this time is 3 to 300 μc/
g is desirable, particularly 10 to 100 μC/g.

In order to prevent fogging, it is preferable to apply a DC voltage and an oscillating electric field for vibrating the toner between the image carrier 1 and the sleeve 2a using a power source. In this case, the distance between the two becomes a problem.

If this distance is made too narrow, electric discharge will occur between the two, damaging the image carrier and preventing the toner from being conveyed between the two.

On the other hand, if the distance between the two is too wide, the opposing electrode effect will be reduced, sufficient development density will not be recorded, and the edge effect will also increase. According to experiments, the distance between them is 2000 pm
In particular, desirable results were obtained when the thickness was between several to ihm and 10 μm.

The DC bias voltage to prevent fogging is usually kept at a higher potential than the non-image area, so the DC bias voltage is 50 to 5 (I
In order to apply a voltage of OV and cause the developer to vibrate, the voltage is 100 to 10 +<r-iz, preferably 1 to 5IG.
An alternating current with a frequency of 1z is used. Direct current type [r may be smaller than this if the toner has magnetism. When performing reversal development, it is natural that a higher direct current [E] is applied. The higher the AC voltage value is, depending on the frequency, the more it vibrates the developer, but on the other hand, fogging and discharge are more likely to occur. As the frequency increases, the developer layer cannot keep up with this change, and there is a tendency for the developed density and sharpness to decrease and the image quality to deteriorate.

As the carrier particles in the present invention, particles that are the same as conventional magnetic carrier particles can be used, except for the average particle size. In other words, metals such as iron, chromium, nickel, and cobalt, or their compounds and alloys, such as triiron tetroxide, γ-ferric oxide, chromium dioxide, manganese oxide, ferrite, and manganese-copper thread alloy, etc. Particles of magnetic or paramagnetic material, or the surface P of these particles
Insulating particles coated with resins such as styrene resin, vinyl resin, ethylene resin, rosin modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, or fatty acid wax such as balditic acid or stearic acid. can be used.

However, among these, insulating magnetic particles with a resistivity of 108 Ωm or more, particularly preferably +(1" Ωm or more) are particularly preferred. If the resistivity is low, when a bias voltage is applied to the developer transport carrier, the carrier particles A charge is injected into
Problems arise in that the carrier tends to leak from the developing container, that a sufficient bias voltage is not applied, and that carriers that have passed through the regulating portion cause breakdown in the developing area.

The resistivity is determined by placing the particles in a container with a cross-sectional area of 0.50 d, tapping them, and then tapping them on the packed particles for 1 h.
/ Apply a load of CnI, and place 1 between the load and the bottom electrode.
This value is obtained by reading the current value when applying a voltage that generates an electric field of 000 v/crIT.

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 manufactured in the same manner as conventional carrier particles, and the average particle size is selected by a conventionally known average particle size selection means before being used in the present invention.

As for the toner particles in the present invention, toner particles obtained by sorting conventional non-magnetic or magnetic toner particles by an average particle size sorting means can be used. And are the toner particles magnetic particles? It is preferable that the magnetic particles contain 3Q, and particularly preferable that the content of the magnetic fine particles does not exceed 3Q wt%. When the toner particles contain magnetic particles, the toner particles are influenced by the magnetic force of the magnet included in the developer transport carrier 2, so that the uniform formation of the toner layer is further improved. The occurrence of fogging is prevented, and furthermore, the scattering of toner particles becomes 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 large, and the toner layer formed on the sleeve becomes thin, making it impossible to obtain a developing density of 1 minute. In addition, fine magnetic particles may 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.
The toner particles described above use fine particles made of the resin described for the carrier particles, and are coated with a coloring component such as carbon and a charge control agent if necessary. etc.,
Conventionally known toner particles-'! It can be made by a method similar to the JJ making method.

The developer of the present invention is a mixture of carrier particles and toner particles as described above in the same proportions as in conventional two-component developers, but if necessary, fluidization and slipping of the particles may be prevented. 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.

Superplasticizer and 1. In this case, colloidal silica, silicone varnish, gold soap, nonionic surfactants, etc. can be used, and as cleaning agents, fatty acid metal salts, organic group 1a-substituted silicones, fluorine, etc. can be used as surfactants. .

FIG. 4 shows yet another embodiment. 1 is a non-magnetic sleeve that rotates in the direction of the arrow. The diameter is 20 In fl and the rotation speed is 1 (10 rpm.FfJ
, li miss linear velocity was set to be the same as the linear velocity of the image carrier. 3 is an image carrier on which 3e is deposited. The potential formed by image exposure is 800cm for the black background area and 50cm for the white background area.
It is V. As a developer, an insulating carrier in which spherical ferrite particles with an average particle size of 80 μm are coated with a resin and an insulating toner with an average particle size of 10 μm are stored in the developer container 5 at a ratio of 1O:1, and consumed by development. It is designed to replenish the toner that has been removed. The toner charger is -I
μc/g.

The gap between the magnetic body 11 made of iron that regulates the development opening and the circumferential surface of the sleeve 1 is maintained at 0.3 inches, and the sleeve rotates at 50 rpm in the direction of the arrow. Further, a developing area AX'r is formed by being held at a gap of 0.3 Hl between the circumferential surface of the image carrier 3 and the circumferential surface of the developing sleeve 1. Further, the sleeve surface is preferably blasted to form irregularities of 5 to 20 μm.

As the sleeve 1 rotates, the magnetic developer in the developer accommodating portion 5 passes over the magnet 7 disposed opposite the magnetic body 4 . At this time, the passage of the carrier C is regulated by the regulating section, and the sleeve 1 is conveyed to the development area A with only the toner 1' attached thereto, and the latent image on the image carrier 3 is developed.

The developing bias voltage that increases by applying the power is C200V and A, C1000V, 2, which is applied to sleeve 1.
An oscillating voltage of r<oz is applied.

In addition, when the magnetic body 4 in FIG. 1 is fixed without rotating, the carrier C easily passes through the regulating portion, and the developer regulating effect 3 as shown in the "quadratic" cannot be obtained.

FIG. 1 is an explanatory diagram of main parts showing another embodiment of the present invention. Two magnets 7a of different polarity are fixed in the sleeve l,
7b are lined up and a closed magnetic field is formed between them and the rotating magnet bar 11.

By doing so, even if the carrier passes through the upstream regulating section, it can be prevented from passing through the downstream regulating section.

FIG. 5 shows another embodiment of the present invention, that is, a developing device a? having the toner layer forming device shown in FIG. FIG. In order to keep the toner layer formed on the developing sleeve 1 stable at all times, it is desirable to once remove the toner remaining on the circumferential surface of the sleeve 1 after development.

If residual toner is left on the developing sleeve l, the undeveloped areas on the developing sleeve and the slag on the developed areas where no toner remains will be replaced by new toner supplied onto the developing sleeve. However, 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. Therefore, it is necessary to scrape off the residual toner. As a scraping method, Mylar board, Rin I
There is a method in which a copper plate, a brush, a sponge roller, or the like is brought into contact with the circumferential surface of the developing sleeve at a position after the development is completed.

In the embodiment shown in FIG. 5, the sponge roller 9 is rotated in the same direction as the magnetic rod and brought into contact with the developing sleeve l on the upstream side of the developer replenishing section 11 to scrape off residual toner. Further, a stirring plate 8 for rotating and stirring 3 is provided in the developer accommodating portion to uniformize the developer and to perform sufficient frictional charging between the carrier and the toner. Also,
It is preferable that the magnetic rod 1 has the same potential as the developing sleeve or is floating.

〔Effect of the invention〕

When using the developing device described below, two-component development is carried out to produce a uniform and stable image of only sufficiently charged toner.
, a thin layer can be formed on the developing sleeve, and unevenness in the toner layer such as white streaks caused by agglomerated toner at the blade can be eliminated, resulting in a good image with no density unevenness. This allows the maintenance cycle to be extended by 3.

It also has the effect of resolving the difficulty in installing the blades with precision. Since a stable thin layer of toner can be obtained on the developing sleeve, a developing device has been provided that can produce good images even through non-contact development.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main part showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the magnetic field of the regulating part, Fig. 3 is an explanatory diagram when the regulating member is rotated, and Fig. 71 is an illustration of the magnet 2. Fig. 5 is a sectional view of a main part showing still another embodiment of the present invention, Fig. 5 is an explanatory drawing of the occurrence of white streaks. 1... ... Sleeve 2 ... Blade 3 ... Image carrier 4 ... Magnetic body (rod) 5 ... Toner storage section 6 ...
・Permanent magnet 7...Magnet 8...
... Stirring plate 9 ... Sponge roller 10 ...
...Developer'r...Toner C...
Group/Career Applicant Konishi Rokusada Kogyo Co., Ltd. Figure 1 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A developing device using a two-component developer consisting of a magnetic carrier and a toner, which has a magnet disposed within a developing sleeve and a rotating magnetic body positioned opposite to the developing sleeve, and both 1. A developing device comprising a toner layer forming means that allows toner to pass through while blocking magnetic carrier from passing through by a cooperative action of the above. (2) The developing device according to claim 1, wherein the magnets arranged in the developing sleeve are arranged in a row of magnets having different polarities. (3) The magnetic carrier has an average particle size of 20 to 200 μm
The developing device according to claim 1 or 2, characterized in that the developing device is located between.