JPH0220111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating method for developing an electrostatic latent image with a non-magnetic developer.

Conventionally, various devices have been proposed and put into practical use as dry one-component developing devices. However, in any of the development methods, it is extremely difficult to form a thin layer of dry one-component developer, and for this reason, a developing device has been constructed by forming a relatively thick layer. However, as improvements in the clarity, resolution, etc. of developed images are currently being sought, it is essential to develop a method for forming a thin layer of a dry one-component developer and an apparatus therefor.

As a method of forming a thin layer of a conventionally known dry type one-component developer, Japanese Patent Laid-Open No. 54-43037 has been proposed and has been put into practical use. However, this concerned the formation of a thin layer of magnetic developer. Magnetic developers must have a magnetic material added to them in order to have magnetism, which causes poor fixing properties when heat fixing the developed image transferred to transfer paper, and adding magnetic material to the developer itself. There are problems such as poor color reproduction during color reproduction.

For this reason, as a method for forming a thin layer of non-magnetic developer,
Proposed methods include using a cylindrical brush made of soft beaver hair to apply the developer, and applying the developer to a developing roller with a surface made of fibers such as velvet using a doctor blade. has been done. However, if an elastic blade is used as a doctor blade for the above fiber brush,
Although it is possible to regulate the amount of developer, uniform application is not achieved, and the fiber brush on the developing roller is simply rubbed, and no triboelectric charge is imparted to the developer existing between the fibers of the brush. Therefore, there was a problem that ghosts and the like were likely to occur. Furthermore, since the device includes a non-magnetic developer, it is difficult to prevent the developer from leaking from the device.

The present invention eliminates the problems of the conventional method described above, forms the developer as a uniform thin layer on the surface of the developer holding member, provides sufficient triboelectric charging, and maintains stable and uniform development even during continuous development. The object of the present invention is to provide a novel coating method that forms a thin layer of developer. A further object of the present invention is to make it possible to prevent the non-magnetic developer from leaking out of the developing device.

That is, the present invention provides a container for storing a non-magnetic developer containing non-magnetic toner and magnetic particles, a developer holding member for rotationally conveying the non-magnetic developer to a latent image carrier, and a non-magnetic material of the container. Located on the developer supply outlet side.
A regulating member disposed with a gap formed on the surface of the developer holding member, and a regulating member disposed on the opposite side of the regulating member across the developer holding member and located on the developer outlet side of the container. A fixed magnet having at least one magnetic pole for forming a magnetic brush made of magnetic particles and for restraining is arranged on the upstream side, and by rotating the developer holding member, a non-magnetic developer is placed on the developer holding member. In the coating method for forming a thin layer, magnetic particles are coated with a resin and the triboelectric charging characteristics of the non-magnetic toner with respect to the developer holding member and the triboelectric charging characteristics of the magnetic particles with respect to the developer holding member are of the same polarity. The present invention relates to a coating method characterized in that a thin layer of the non-magnetic developer is formed on a developer holding member by passing the non-magnetic developer through the formed magnetic brush.

With the method according to the present invention, the developing method is as follows:
In addition to those that take advantage of the so-called one-component jumping development as shown in No. 54-43037, even non-magnetic developers can be applied neatly onto the developer carrier.

In addition, in the method of the present invention, the adhesion and releasability of the non-magnetic developer and magnetic particles, and the triboelectricity and fluidity of the non-magnetic developer greatly affect coating and development.
By using magnetic particles coated with a resin having triboelectric charging properties of the same polarity as the non-magnetic developer, it is possible to adjust the physical properties of the developer and achieve a good coating state.

The latent image carrier of the present invention is a drum-shaped or belt-shaped member having a photoreceptor or an insulating layer, and the magnetic pole is a magnetic roller with magnetic poles of the same polarity or different polarity magnetized in the axial direction. Alternatively, a plurality of rod-shaped magnets bonded onto a fixed support member may be used. Furthermore, as the rotating developer holding member, it is possible to use a sleeve made of non-magnetic metal such as aluminum, copper, stainless steel, brass, etc. or a synthetic resin material, or an endless belt made of resin or metal, whose circumferential surface is used to convey the toner. In order to improve the electrostatic properties and charging characteristics, the surface may be roughened or provided with an uneven pattern, if necessary. In addition, as a regulating member, magnetic materials such as iron, aluminum,
A blade plate or wall made of non-magnetic material such as copper or resin may be used.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a sectional view of a developing device for explaining the developing principle to which the coating method of the present invention is applied.

In the figure, reference numeral 1 denotes an electrophotographic photosensitive drum, which holds a latent image formed by a latent image forming means (not shown), and rotates in the direction of arrow a to pass through a developing position shown in the drawing. A non-magnetic sleeve 2, which is a developer holding member that holds developer, faces the photosensitive drum 1 with a predetermined gap maintained therebetween, and this sleeve 2 rotates in the direction of arrow b. A container 3 made of a non-magnetic material such as resin or aluminum is located above the sleeve 2 and stores a mixture of a non-magnetic developer 4 and covered magnetic particles 5.
A magnetic blade 6 is screwed to the downstream side of the sleeve in the rotating direction.

On the other hand, the sleeve 2 for this magnetic blade 6
A magnet 7 is provided on the opposite side. The installation position of this magnet is determined by the position of the magnetic pole and the magnetic blade 6.
In fact, the effect of the magnetic field created by providing a magnetic pole slightly upstream of the position of the magnetic blade 2 is even better in terms of preventing magnetic particles from flowing out and uniformly applying the developer. get good results.

In the above configuration, the covered magnetic particles 5 in the container 3 form a magnetic brush 8 due to the magnetic field generated between the S pole of the magnet 7 and the magnetic blade 6. Then, as the sleeve 2 rotates, the covered magnetic particles and the non-magnetic developer are stirred and mixed while the magnetic brush 8 is held. In this state, on the magnetic blade side of the container 3, due to the presence of the blade 6, the mixture of developer and magnetic particles is prevented from moving by the blade, rises, and circulates in the direction of arrow c.

As a result, the non-magnetic developer is triboelectrically charged by the sleeve 2 or the covered magnetic particles by mixing with the covered magnetic particles. The charged developer is
A magnetic brush 8 formed near the magnetic blade 6 applies a thin, uniform coating onto the surface of the sleeve 2 due to mirroring force, and reaches a position facing the photoreceptor drum.

By the way, the covered magnetic particles 5 constituting the magnetic brush 8 do not flow onto the sleeve 2 by setting the restraining force due to the magnetic field of the magnet 7 to be larger than the conveying force caused by the frictional force. If there is a non-magnetic developer within the area of the magnetic brush 8, the ratio of the magnetic particles covered by the magnetic brush 8 to this developer is determined by the electrostatic charge due to the same polarity between the magnetic particles covered and the non-magnetic developer. It maintains a substantially constant value due to the repulsion force and the rotation of the sleeve 2. Thereby, even if the developer on the sleeve is consumed during development, the developer is automatically supplied to the area of the magnetic brush 8. Therefore, it is possible to always supply and apply a constant amount of developer onto the sleeve 2.

In addition, in the above explanation of the principle, a magnetic blade is used as the regulating member, but the non-magnetic blade or the wall of non-magnetic material such as resin or aluminum that constitutes the container can be
It can also be used as this regulating member. However, in this case, in order to prevent the covered magnetic particles from flowing out, it is necessary to make the gap between the sleeve and the regulating member even smaller than when using a magnetic blade. Further, when a magnetic blade is used, it is preferable because a magnetic brush can be stably formed at the developer outlet by the magnetic field between the blade and the magnetic pole.

By the way, in the developing device shown in FIG. 1 above,
Since the developer is a non-magnetic developer, there may arise a problem that it tends to leak from the region d on the side where the sleeve 2 enters the container 3. In order to prevent the developer from leaking from the area d, a magnetic brush may be formed between the sleeve and the container on the side where the sleeve enters the container.

The coated magnetic particles used in the present invention include, for example, surface oxidized or unoxidized iron nickel,
Metals such as cobalt, manganese, chromium, rare earths,
and those coated with magnetic particles such as alloys or oxides thereof can be used. The shape of these magnetic particles may be spherical, flat, acicular, porous, or any other shape.

A method of coating the magnetic particle surface so that it has the same polarity as the toner is, for example, by dissolving and dispersing a coating resin, or a coating resin and a charge control agent in a solvent (toluene, xylene, MEK), etc., and dispersing this dispersion. Examples include a method in which fine magnetic particles are mixed with the magnetic particles, coated on the magnetic particles by a spray dryer method, fluidized bed method, etc., dried, granulated, sieved, and the passed through is used as coated magnetic particles.

When used for positively charged toner,
As the coating resin, positively charged resins such as resins formed from dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, or copolymers of these and styrene compounds are used, and as positive charge control agents, nigrosine and copper are used. Phthalocyanine, quinophthalone, various dyes and pigments showing positive chargeability, etc. can be used.

When used for negatively chargeable toner, the coating resin may include polyvinyl chloride, polyethylene, polypropylene, α-chlorostyrene,
Negatively chargeable resin such as polyester can be used. Further, as the negative charge control agent, chromium chelate of tert-butylsalicylic acid and various dyes and pigments exhibiting negative chargeability can be used.

As the binder resin of the non-magnetic developer used in the present invention, monopolymers of styrene and its substituted products such as polystyrene, polyP-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, styrene- Propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-acrylic-aminoacrylic copolymer, styrene-amino Acrylic copolymer, styrene-alpha chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl ether copolymer,
Styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, etc. Styrenic copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin terpene resin, Phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

In the non-magnetic developer of the present invention, any suitable pigment or dye can be used as a colorant. For example, there are known dyes and pigments such as carbon black, iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

In addition, as charge control agents, amino compounds, quaternary ammonium compounds, organic dyes, especially basic dyes and their salts, benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, safranin γ and crystals are used. Violet, metal-containing dyes, salicylic acid metal-containing compounds, etc. may be added.

The structure of the non-magnetic developer described above may be used for a developer by the commonly used mixing and pulverizing method, or may be used for the wall material and/or the core material of a microcapsule developer.

[Example 1] An example of the present invention will be described with reference to FIG. In the figure, the same members as in FIG. 1 are given the same reference numerals. In the embodiment device, the photoreceptor drum 1 is indicated by arrow a.
Rotates in the direction at a peripheral speed of 60mm/sec. 2 is arrow b
It is a stainless steel (SUS304) sleeve with an outer diameter of 32 mm and a thickness of 0.8 mm that rotates at a circumferential speed of 66 mm/sec in the circumferential direction. The surface roughness was set to 0.8 μm (R _Z =).

On the other hand, a ferrite sintered type magnet 7c is fixedly disposed inside the rotating sleeve 2, and the first
The north pole of the magnetic pole is set at an angle of 30 degrees (θ in the drawing) with respect to the magnetic blade 6 from a line connecting the center 0 of the sleeve 2 and the tip of the blade. S of one second magnetic pole
The pole is located opposite to an iron piece 10, which is a magnetic member, provided on the sleeve inlet side of the container. The magnetic flux density on the sleeve surface of the second magnetic pole had a peak value of 650 Gauss in the presence of the iron piece 10, and 400 Gauss with the iron piece 10 removed.
Regarding the positional relationship between the magnetic poles and the iron piece 10, the width of the iron piece in the sleeve rotation direction was set to 0.5 mm, and the distance between the sleeve 2 and the iron piece was set to 1.0 mm.

The magnetic blade 6 is made of iron and has a nickel plated surface to prevent rust. The distance between the blade 6 and the surface of the sleeve 2 was set to 200 μm.

As the non-magnetic developer 4, per 100 parts of styrene-maleic acid copolymer, 10 parts of perylene red pigment,
Average particle size with 5 parts of negative charge control agent (alkyl salicylate metal complex) added internally and 0.5% silica externally added.
200 g of red powder charged with negative (-) polarity was prepared for a 10.6 μm sleeve.

On the other hand, the particle size of the covered magnetic particles is 70~
100g of spherical ferrite of 100μ, maximum 60emu/g,
20 g of polyester resin and 2 g of alkyl salicylic acid metal complex were dissolved in 200 ml of toluene, which was added to a solution, stirred for 60 minutes, dried, and sieved to prepare negatively charged magnetic particles for the covered sleeve.

After thoroughly mixing the non-magnetic developer and the covered magnetic particles, they are placed in the container 3. The mixture of the non-magnetic developer and the covered magnetic particles in the container 3 has a circular movement in which the covered magnetic particles are conveyed by the sleeve under a magnetic field.
It was observed that the developer was running low.

In the developing device configured as described above, as the sleeve rotates, the surface of the sleeve 2 has approximately
A thin layer of 110 μm thick made only of non-magnetic developer could be formed. When the charging potential of this developer layer was measured by a blow-off method, it was confirmed that the developer layer was uniformly charged with a potential of -9.8 μc/g.

On the surface of the photoreceptor drum 1 facing the sleeve 2, an electrostatic latent image is formed with a dark area of +600V and a bright area of +150V.
to form a charge pattern and increase the distance from the sleeve surface.
It was set to 300μm. Then, the frequency of 800Hz and the peak-to-peak value was set to the above sleeve by power source E.
When we applied a voltage of 1.4KV with a center value of +300V, we were able to obtain high-quality developed images with no uneven development, ghost images, or fog.

Further, regarding the mixture in container 3, the magnetic particles covered therein were hardly consumed, and only the non-magnetic developer was consumed for development. Further, the developing function remained unchanged until almost all of the developer was consumed. After the developer was consumed, the developing device was removed from the main body and the lower part of the sleeve 2 was looked at, and it was found that not only were there no magnetic particles, but there was almost no developer leakage there.

[Example 2] As a non-magnetic developer, 100 parts of styrene-acrylic copolymer and 15 parts of copper-phthalocyanine pigment were internally added and 0.5ωt% of silica was externally added.
11.0μm positively charged red powder
I prepared 200g.

The covered magnetic particles were prepared by adding 100 g of the ferrite used in Example 1 to a solution of 20 g of dimethylaminoethyl methacrylate resin in 200 ml of DMF.

After mixing both, put it in container 3 and continue to use it for 10 minutes.
Although the sleeve 2 was idled for several hours, a thin layer of about 140 .mu.m thick of non-magnetic developer was formed on the surface of the sleeve 2. When the charging potential of this developer layer was measured by a blow-off method, it was confirmed that the developer layer was uniformly charged with a potential of +11.6 μc/g.

On the surface of the photoreceptor drum 1 facing this sleeve 2, an electrostatic latent image is formed with a dark area of -600V and a bright area of -150V.
to form a charge pattern and increase the distance from the sleeve surface.
It was set to 300μm. Then, the frequency of 800Hz and the peak-to-peak value was set to the above sleeve by power source E.
When we applied a voltage of 1.4 KV with a center value of -300 V, we were able to obtain a high-quality, clear red developed image with no uneven development, ghost images, or fog.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a developing device for explaining the principle of the present invention. FIG. 2 is a sectional view of a developing device used in an embodiment of the present invention. In the figure, 2 is a sleeve which is a developer holding member, 3 is a container, 4 is a non-magnetic developer, 5 is a magnetic particle, 6 is a magnetic blade which is a regulating member, 7 is a magnet, and 10 is an iron piece which is a magnetic member. show.

Claims (1)

[Scope of Claims] 1. A container for storing a non-magnetic developer containing non-magnetic toner and magnetic particles, a developer holding member for rotationally conveying the non-magnetic developer to a latent image carrier, and a non-magnetic developer of the container. Located on the magnetic developer supply outlet side.
A regulating member disposed with a gap formed on the surface of the developer holding member, and a regulating member disposed on the opposite side of the regulating member across the developer holding member and located on the developer outlet side of the container. A fixed magnet having at least one magnetic pole for forming a magnetic brush made of magnetic particles and for restraining is arranged on the upstream side, and by rotating the developer holding member, a non-magnetic developer is placed on the developer holding member. In the coating method for forming a thin layer, magnetic particles are coated with a resin and the triboelectric charging characteristics of the non-magnetic toner with respect to the developer holding member and the triboelectric charging characteristics of the magnetic particles with respect to the developer holding member are of the same polarity. A coating method comprising forming a thin layer of the non-magnetic developer on the developer holding member by passing the non-magnetic developer through the formed magnetic brush.