JPS62182775A - Developing method for electrostatic latent image - Google Patents

Abstract

PURPOSE:To form a visible image of high definition which has a sufficient image density and is superior in resolving power and gradation reproducibility, by specifying the particle size and the quantity of a fluidizer added to a toner. CONSTITUTION:A developer layer is made thin, and the toner is used which includes 0.1-1.0pt.wt. fluidizer, which has 7-20mum average particle size by the BET method, per 100pts.wt. toner, and the weight average particle size of the toner is set to 6-20mum. The fluidizer reduces properly the sticking strength between carrier particles and toner particles to make it easy to fly the toner and raises the image density to reduce the photographic fog. If the average particle size of the fluidizer is <7mum, it is hidden in the toner surface and its effect does not appear; and if it is >20mum, it is difficult that the fluidizer is stuck to the toner surface, and the fluidizing function is not fulfilled. If <0.1pt.wt. fluidizer is added to 100pts.wt. toner, the effect is not remarkable; and if >1.0pt.wt. fluidizer is added there, the toner is scattered to cause the photographic fog, and the resolving power is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method of developing an electrostatic latent image, for example, to a method of developing an electrostatic latent image to visualize an electrostatic latent image in electrophotography. .

BACKGROUND ART Conventionally, as a method for developing a latent image on an image carrier in an electrophotographic copying device, etc., there are two methods: a method using a one-component developer that imparts magnetism to the toner itself and eliminates the need for a carrier; There is a method using a two-component developer consisting of a magnetic or slightly magnetic toner and a magnetic carrier. The latter method is widely adopted because it has the advantages of easy control of triboelectrification of the toner, excellent developability, and the ability to impart any color to the toner. In two-component developers, attempts have been made to reduce the particle sizes of carrier and toner in order to improve the resolution, gradation reproducibility, and other overall image quality of the resulting images.

For example, Japanese Patent Application Laid-Open No. 59-18136, which was previously proposed by the present applicant.
No. 2, No. 59-222847, No. 59-222851
No. 59-222852, No. 59-222853, No. 59-223467, each publication has a
A technique of developing by touch instead of using a carrier having a large particle size of m is described.

However, when the toner in the developer is made to have a small particle size, the binding force between the developer transport carrier and the toner becomes weaker, and the gallia and toner scatter during the handling of the developer and the process of image formation, causing damage to the image forming device. There have been problems such as contamination of the inside, adhesion to the image surface and blurring, and the inability to obtain a clear image.

In order to prevent fogging, it is sufficient to increase the gap between the image carrier and the developer 1 transfer carrier, but this weakens the developing electrode effect and makes it difficult to perform sufficient development. Generating a large oscillating electric field between the image bearing member and the developer transporting carrier improves the developing performance, but it also increases fogging and carrier scattering due to toner adhesion to non-image areas, and also causes problems in the developing device. Electrical isolation becomes a major design hurdle.

C.1 Purpose of the Invention As a result of extensive research, the present inventor found that the particle size and amount of fluidizing agent added to toner have a significant effect on developability and fogging. The present invention has been made based on the above findings.

That is, the object of the present invention is that, even though the image is developed using a developer composed of toner and a carrier having a small particle size, 7η in the image forming apparatus due to scattering of the carrier and toner.
Scattered carriers may adhere to the dyed or image surface, or l may appear on the non-image area.
・Good development is achieved without causing problems such as dusting due to toner adhesion, and appropriate frictional charging is applied between the carrier and toner, resulting in a sufficient image. The object of the present invention is to provide a developing method that enables the formation of clear visible images with excellent temperature, resolution, and gradation reproducibility.

When developing with the rear and toner-containing developer layer, an oscillating electric field is generated in the developing area, and the average particle diameter due to image bearing is 7 to 20 mμm and 0% to 100 parts by weight of toner.
．． The present invention relates to a method for developing an electrostatic latent image, using a toner containing 1 to 1.0 parts by weight of a fluidizing agent and having a weight average particle size of 6 to 20 μm.

The fluidizing agent has the function of appropriately lowering the adhesive force between carrier particles and toner particles, making it easier for toner to fly during development, increasing image density, and reducing fog.

When the average particle size of the fluidizing agent increases by 7 mpm according to the BET method,
It becomes difficult to adhere to the toner surface and the fluidizing function cannot be achieved.

The amount of fluidizing agent added is 0.00 parts by weight per 100 parts by weight of toner.
If the amount is less than 1 part by weight, the above effect is not noticeable, and if it exceeds 1.0 part by weight per 100 parts by weight of toner,
The adhesion force between the toner and the carrier is reduced, and the toner scatters, contaminating the inside of the developing device, causing image fogging, and reducing resolution.

If the weight average particle diameter of the toner is less than 6 μm, toner scattering becomes severe and fogging tends to occur, and if it exceeds 20 μm, the resolution decreases.

E. Examples First, particularly preferred embodiments of the present invention will be described.

In the present invention, when a two-component developer is used and no developing bias is applied, the image bearing member and the developer layer on the developer transport carrier are kept in a state of not contacting each other, and under the oscillating electric field caused by the alternating current bias component. Particularly preferred is a non-contact development method in which the toner is caused to fly and selectively adhere to the latent image portion of the image carrier.

In the developing method of the present invention, preferably the developer is configured as described below, the developing area (an image bearing member and a developer transporting carrier face each other, and the transported toner is electrostatically applied to the image bearing member). The thickness is 200 mm
0 μm or less, preferably 1000 μm or less, more preferably 10 to 500 μm 1 More preferably 10 to 400 μm
Even in non-contact development, the developer layer, which is unprecedentedly thin in μm, allows development to be performed with a small gap between the image carrier and the developer transport carrier. Even if the bonding force between the carrier and toner of the developer used here or the bonding force between the carrier and the developer transport carrier is weak, since the developer layer is extremely thin, the developer The developer is sufficiently fixed to a transport carrier (hereinafter referred to as a sleeve as the developer transport carrier is almost always in the form of a sleeve),
No scattering.

In this case, even if the toner in the thin layer on the sleeve is lost during development, the developability will not be affected as long as sufficient toner is immediately supplied to the thin layer. For this purpose, it is preferable to rotate a magnet (magnetic roll) built into the sleeve at high speed.

Next, in order to develop the small amount of developer transported to the developing area with maximum efficiency, (1) high speed rotation of the magnetic roll (2) application of AC bias to the sleeve (3) connection between the image forming body and the sleeve. It is preferable to take measures such as reducing the gap.

In the non-contact development method, by making the developer layer thinner, the gap between the image forming body and the sleeve can be reduced, and the developing bias voltage required to form the oscillating electric field required to fly the toner can be lowered. . Therefore, in addition to reducing toner scattering from this point of view, when developing bias is applied from the sleeve surface, the electric field strength formed in the developing area due to the latent image increases, resulting in subtle changes in gradation. It becomes possible to develop even kana patterns.

A thinner layer generally results in less toner being transported to the development zone, resulting in a smaller amount of development. When the linear velocity ratio with the conveyor becomes 1:10, the developing toner force <? The velocity component parallel to the image plane increases, causing directionality in development and deteriorating image quality.

From this, the lower limit of the thin layer is set as follows: when the toner is deposited on the sleeve surface at a density of at least Q, 04 mg/ct, and the amount of toner in the thin layer on the sleeve is m. need to be met.

In consideration of development efficiency, it is preferable to use .

At this time, the ratio of toner to carrier in the developer is such that the ratio of the total surface area of toner to carrier in a unit volume is 0.5 to
It is preferable that it be 2.

By setting the above conditions, the toner in the thin layer can be efficiently developed, the developability is stable, and good image quality can be obtained.

As a means for forming the thin developer layer, for example,
Conventionally known layer thickness regulating members, such as a regulating plate, preferably made of a magnetic material, disposed at a certain distance from the sleeve, and a magnetic roll disposed close to the sleeve, regulating the developer layer thickness by a rotating magnetic field. Both are used. In particular, in order to eliminate impurities such as dust, fibers, paper powder, or aggregates of toner or carrier contained in the developer, a thin layer forming member consisting of a pressing plate that is elastically and lightly pressed against the sleeve is used. Preferably used.

This thin layer forming member is an elastic plate that is pressed against the sleeve so that its tip faces upstream of rotation of the sleeve, and forms a thin layer by letting the developer slip between the sleeve and the elastic plate.

FIG. 3 shows the relationship between the gap (=opening area) between the tip of the elastic plate and the sleeve and the amount of developer adhering to the sleeve.

It can be seen from the figure that when the gap exceeds a certain value, the amount of developer on the sleeve is stable against these changes.

In this stable state, the toner necessary for the above-mentioned development can be sufficiently transported. From other experiments, it has been shown that the layer thickness hardly changes and other parameters are stable at 4JG.
It has become clear that there is no sign of aging.

Therefore, if the gap at the tip is set to 0.08 mm or more,
It is possible to stably transport a certain amount of toner regardless of the accuracy or mechanical accuracy of the installation. Further, it is preferable to set the gap at the tip to 0.1 mm or more because stability will be increased.

Of course, it is not desirable to make the gap at the tip so large, and it has been observed that when the gap is increased to 5 mm or more, the uniformity of the developer layer is disrupted.

The carrier used in the present invention has magnetization M (unit: em
u /cnt) (provided that the applied magnetic field for measurement is 1000 oersted) and the particle size R (unit: μm) satisfy the following relational expression, and a carrier having a resin coating layer on the surface is preferably used.

30≦M≦−〇, 8 R+150 (However, 10≦R≦150, preferably 20≦R≦60
) As mentioned above, in the non-contact development method that applies an alternating electric field, the shorter the distance between the photoreceptor and the developing sleeve, the better the developing performance and the higher the resolution of the image. (That is, the development gap) is desirably set to 1 mm or less, preferably in the range of 0.3 to 0.7 mm.

However, it is impossible to maintain the developer in a non-contact state with the photoreceptor under these conditions using a developer using a carrier having the particle size and magnetization used in the two-component development method of the normal contact method. It has been found. However, according to the present invention, it has been found that extremely satisfactory results can be obtained by using a carrier that satisfies the above relational expression and has an insulating coating layer on its surface.

That is, in the above, it has been found that when M and R satisfy the above relational expression, the height of the magnetic brush on the developing sleeve is sufficiently low and suitable for non-contact development. Conversely, if M is less than 30, the magnetization is too weak to form the desired magnetic brush, and (-0,8R+150
), the magnetization is too large and unsuitable for non-contact development.Also, the particle size (R) of the carrier is also important, and when R is between 10 and 11'!J, the magnetic binding force of the carrier is weak. If R is larger than 150, the magnetic brush will become sparse, making it difficult to obtain a good image even after development, or the magnetic brush will become weak due to the It becomes impossible to form stably.

Here, the above particle size (R) means the average particle size of the carrier, and is generally preferably 20 to 60 μm.

At the same time, the magnetization (M) is 40-10100e/cn!
It is preferable that

FIG. 1 shows a sectional view of a developing device suitable for carrying out the developing method of the present invention. In the figure, 20 is an image carrier, 2 is a housing, 3 is a sleeve, 4 is a magnetic roll having N and S8 poles, 5 is a layer forming member, and 6 is a fixing member for this member.
7 is a first stirring member, and 8 is a second P#, a pushing member. 9 and 10 are rotating shafts of the stirring members 7 and 8, 11 is a replenishment toner container, 12 is a toner replenishment roller, I3 is a developer reservoir, 14 is a developing bias power source, 15 is a developing area, T is a toner, and D is a developing area. represents an agent. In this developing device, the developer pool in the developer reservoir 13 is sufficiently agitated and mixed by the first stirring member 7 rotating in the direction of the arrow and the second stirring member 8 rotating in the opposite direction so as to overlap with each other. , the sleeve 3 rotates in the direction of the arrow and the magnetic roll 4 rotates in the opposite direction.

A thin layer forming member 5 held by a fixing member 6 extending from the housing 2 is pressed into contact with the surface of the sleeve 3 at a surface near the end, and the layer thickness of the developer transported as described above is controlled. to regulate. This developer layer is in the development area 15.
The latent image on the image carrier 20 rotating in the direction of the arrow is developed in a non-contact manner across a gap to form a toner image. During development, a developing bias containing an alternating current component is applied to the sleeve 3 from the power source 14, and as a result, only the toner in the developer on the sleeve 3 selectively moves and adheres to the surface of the latent image. Note that the layer thickness of the developer can be measured, for example, as follows. That is, using a Nikon profile projector manufactured by Nippon Kogaku Co., Ltd., the layer thickness is determined by comparing the positions of the projected image of the screen on the sleeve and the projected image of the thin layer formed on the sleeve.

The thin layer forming member (elastic plate) 5 is made of, for example, a magnetic or non-magnetic metal, metal compound, plastic, rubber, etc., and is extremely uniformly molded, and has one end fixed by a fixing member 6 to give elasticity. The thickness is 50mm.
~500 μm.

As described above, the sleeve 3 is elastically pressed with the surface near the other end of the thin layer forming member having one end fixed.
The amount of conveyance is regulated by preferably passing the carriers one by one at the contact position between the thin plate and the thin plate. Impurities in the developer, carrier or toner aggregates, etc. cannot pass through the regulation position. Therefore, the developer layer reaching the development area 15 can always be kept thin and uniform and stable.

Note that the conveyance amount of the developer to reach the development area 15 is the above-mentioned gJW.
It is controlled by changing the pressing force and contact angle of the J-forming member 5 against the sleeve 3.

It is said that it is advantageous for the carrier and toner constituting the developer to have small particle diameters from the viewpoint of image resolution and gradation reproducibility. For example, even when the toner particle size in the developer layer is 13 μm or less, and the carrier particle size is as small as 50 μm or less, or even 40 μm or less, by using means such as the thin layer forming member 5 described above, A uniform layer can be formed by automatically removing impurities and agglomerates. Further, even when the carrier has a particle size as small as that of the toner, contamination with impurities is similarly eliminated and a uniform thin layer can be formed.

On the other hand, in order to prevent carrier adhesion to the image bearing member, it is preferable that the carrier particle size is large because it receives a strong magnetic force. For example, even if the carrier particle size is about 20 to 50 μm, a uniform thin layer can be formed by the above method. In addition,
As the carrier particle size increases, the height of the carrier in the thin layer increases, the layer becomes rougher, and developability deteriorates. From this point, the carrier particle size is such that the magnetization is, for example, 20 to 30e.
In the case of about mu/g, it is desirable to set it to 50 μm or less.

A perspective view and a front view showing the specific structure of the stirring members 7 and 8 incorporated in the developing device are shown in FIGS.
is shown. In the figure, 7a, 7b, and 7c are the stirring blades of the first stirring member, and 8a, 9b, and 8c are the stirring blades of the second stirring member, and there are various types such as square plate blades, disc blades, and elliptical plate blades. They are fixed to rotating shafts 9 and 10 at different angles and/or positions. The two stirring members 7 and 8 are configured so that the stirring areas overlap without the stirring blades colliding with each other, so that sufficient stirring in the left and right direction (Fig. 1) is performed, and the stirring plate is Because of the inclination (Fig. 2), agitation in the front-rear direction (Fig. 1) is also sufficiently performed.

Further, the toner T supplied from the hopper 11 via the supply roller 12 is also uniformly mixed into the developer in a short time.

The developer O, which has been sufficiently stirred and imparted with a desired frictional charge as described above, is regulated by the g1 layer forming member 5 during the process of being deposited and conveyed onto the sleeve 3, forming an extremely thin and uniform developer layer. be done.

This developer layer is conveyed in one direction by the rotation of the sleeve 3, and is also subjected to a magnetic bias having a vibration component by the rotation of the magnetic roll 4 in the opposite direction, and is subjected to complicated movements such as rolling on the sleeve 3. Therefore, when the toner reaches the developing area 15 and develops the latent image on the image carrier 20 in a non-contact manner, the toner is effectively supplied toward the latent image surface. As mentioned above, since the oscillating electric field can be made extremely thin at 500 μm to 10 μm, non-contact development can be achieved even if the gap between the image carrier 20 and the sleeve 3, that is, the development gap is narrowed to, for example, 500 μm. is fully possible. When the developing gear 7 is narrowed in this way, the electric field in the developing area 15 increases, so even if the developing bias applied to the sleeve 3 is small, sufficient development can be achieved.
There is an advantage that leakage discharge of developing bias and the like can be reduced.

Furthermore, since the contrast of the latent image is increased, the resolution and quality of the image obtained by development are generally improved.

Another effect of the present invention is that the developing method is non-contact development, and only the toner is selectively flown toward the latent image surface for development, so that carrier adhesion to the latent image surface is prevented. . In addition, since the latent image surface is not rubbed, there is no damage to the surface of the image forming body or formation of brush marks.
°, power and gradation reproducibility are good, and a sufficient amount of toner can be attached to the latent image surface. Furthermore, it is suitable for image development in which a toner image is formed.

In addition, as stable development conditions in the development method of the present invention, the developer layer has a thickness of 10 to 500 μm, more preferably 40 μm.
0 μm or less, development gap 2008 m to 700 μm
It is preferable that the relationship between the rotational speed of the sleeve 3, the rotational speed of the image carrier 20, and the amount of toner adhering to the sleeve satisfies the above-mentioned equation.

The toner having the following structure is preferably used.

■ Thermoplastic resin (binder) 80-90wt% Examples: polystyrene, styrene acrylic polymer, polyester, polyvinyl butyral, epoxy resin, polyamide resin,
Polyethylene, ethylene-vinyl acetate copolymer, etc., or a mixture of the above■ Pigment (coloring agent) 0-15-t% Example: Black: Carbon Brasov yellow: Benzidine derivative Magenta: Rhodamine B lake, Carmine 6B, etc. Cyan: Phthalocyanine, Sulfonamide dyes, etc.■ Charge control agent 0-5wt% Positive donor: Nigrosine-based electron-donating dye, alkoxylated amine, alkylamide, gylate, pigment, 4
Negative toners such as grade ammonium salts: Electron-accepting organic 2HH bodies, chlorinated paraffins, chlorinated polyesters, polyesters with excess acid groups, chlorinated copper phthalocyanines, etc. ■ Flowing agent 0.1
~1.0 parts by weight The amount of fluidizing agent added also varies depending on the particle size of the toner. The appropriate range also changes depending on the average particle size of the fluidizing agent. The present inventor has determined that the average particle size of the toner is 6 to 20 μm,
In particular, when the average particle size is 8 to 15 μm, adding 0.1 to 1.0 parts by weight, especially 0.2 to 0.8 parts by weight of a fluidizing agent with an average particle size of 7 to 20 mμm can provide good image quality without fog. I found out what I can get.

The toner containing the fluidizing agent has a small adhesion force with the carrier and is easily separated in an oscillating electric field and moves individually. For this reason,
Toner flies easily and is easily developed. Furthermore, since the toner exists uniformly in a cloud-like manner in the developing space, image quality with high resolution can be obtained, unlike ordinary magnetic brush development.

There are two methods for incorporating a fluidizing agent into the toner, including internal addition and external addition, but it is preferable to use an external addition method in which all of the fluidizing agent contributes to improving fluidization.

The fluidizing agent also prevents direct contact between the toner and the carrier, thereby preventing spent toner. Furthermore, the surface of the transport carrier is polished to increase the friction coefficient between the carrier and the carrier, thereby ensuring a constant transport amount at all times. These ensure that the 7i is always stable.
Contributes to iI layer formation.

When the fluidizing agent is uniformly distributed on the toner surface, the counterforce is uniform and the toner particles are uniformly distributed. Therefore, in overlapping development, a uniform solid image with little color difference can be obtained.

As described above, in this developing method, the fluidizing agent acts effectively.

Examples of fluidizing agents include fine particles of metal oxides such as silica, alumina, titania, calcium oxide, magnesium oxide, barium oxide, beryllium oxide, and cerium oxide, as well as those obtained by hydrophobizing these fine particles. can be mentioned. In particular, when using a toner that has been hydrophobized, the fluidizing agent adheres firmly to the toner,
This had the effect of lowering the cohesive force between toners. Furthermore, the moisture resistance of the fluidizing agent is improved, and therefore a stable fluidizing effect can be obtained even in a high humidity atmosphere. Such hydrophobization treatment is carried out by using, for example, the above fluidizing agent fine particles and a silane coupling agent such as dialkyldihalogenated silane, trialkylhalogenated silane, alkyltrihalogenated silane, hexaalkyldisilazane, dimethyl silicone oil, etc. This can be done by reacting a hydrophobizing agent such as silicone oil at high temperature.

Among the above-mentioned fluidizing agents, silica, alumina, and titania are preferred, and those treated with hydrophobization are preferably used in the present invention.

Specific examples of such fluidizing agents include the following.

rR-972j (hydrophobic amorphous silica, average particle size (BE
'r' method) 16 μm, Nippon Aerosil Co., Ltd.) rR
-974j (hydrophobic amorphous silica, average particle size (BE
T method) 12 μm, manufactured by Nippon Aerosil Co., Ltd.) r'R-
976J (hydrophobic amorphous silica, average particle size (BET
method) 7 μm, manufactured by Nippon Aerosil Co., Ltd.) rR-805
j (hydrophobic amorphous silica, average particle size (by BET method)
12 μm, manufactured by Nippon Aerosil Co., Ltd.) rR-812” (hydrophobic amorphous silica, average particle size (by BET method) 7 μm
, manufactured by Nippon Aerosil Co., Ltd.) rR-811J (hydrophobic amorphous silica, average particle size (by BET method) 12 μm1 manufactured by Nippon Aerosil Co., Ltd.) rRA・200Hj (hydrophobic amorphous silica, average particle size (by BET method) 12 μm, Japan Manufactured by Aerosil) rr? X-C4 (hydrophobic alumina, average particle size: 20 μm (manufactured by Nippon Aerosil Co., Ltd.). Also, the surface can be treated with hydrophobization, especially with a silane coupling agent or silicone oil to obtain Sin.

adhered firmly to the toner, and had the effect of lowering the cohesive force between toners.

Surface treatment agent Silane coupling agent Dimethyldichlorosilane Hexamethyldisilazane Silicone oil Dimethylsilicone oil It has also been found that when a friction reducing substance is further added to the toner containing the fluidizing agent, more favorable results can be obtained.

Suitable friction-reducing substances include zinc stearate, lithium stearate, magnesium stearate, barium stearate, and other solid lubricants (for example, molybdenum disulfide, tungsten disulfide), which have good interfold properties.

If the amount of the friction reducing substance added is too large, it will inhibit the toner's charging and tend to cause a decrease in image density and fog, so add 0.0 to 100 parts by weight of the toner.
The amount is preferably 1 to 1.0 parts by weight.

A particularly preferred range is 0.01 parts by weight per 100 parts by weight of toner.
~0.8 parts by weight.

The friction-reducing substance reduces the friction between particles constituting the developer to prevent toner agglomeration and firm adhesion of a thin layer of toner material to the carrier and/or image bearing member.

Further, the toner collides with a large force and adheres to the thin layer forming plate for forming the thin layer. The adhered toner gradually becomes larger and obstructs the conveyance of the developer, appearing as streaks on the image or disturbing the image quality.

By adding a friction-reducing substance to the toner, the impact force of the toner on the thin layer forming plate is weakened (preventing adhesion and growth, ensuring stable conveyance of the developer, and ensuring good image quality over a long period of time). It will be done.

■ Cleaning agent (prevents toner filming on the photoreceptor) Examples: fatty acid metal salts, silicon oxides with organic groups on the surface,
Fluorine surfactants, etc. ■ Fillers (improves image surface gloss, lowers raw material costs: 0
1i) Examples: Calcium carbonate, clay, talc, pigments, etc. In addition to these materials, a small amount of magnetic powder may be included to prevent fogging on the image surface and toner scattering.

As such magnetic powder, triiron tetroxide, γ-ferric oxide, chromium dioxide, nickel ferrite, iron alloy powder, etc. with a particle size of 0.1 to 1 mm are used, and the content is 0.1 to 5 wt%. . Further, the content of the magnetic powder is desirably 1 wt % or less in order to make the color tone of the toner clear, especially the color tone of the color toner.

Suitable resins for pressure fixing toners that are plastically deformed and fixed to paper with a force of about 20 kg/cm include waxes, polyolefins, ethylene-vinyl acetate copolymers, polyurethanes, and adhesive resins such as rubber. used.

A toner can be made using the above-mentioned materials by a conventionally known manufacturing method.

In this apparatus, in order to obtain a more preferable image, the toner particle size (weight average) is less than about 13 μm, especially 10 to 10 μm.
A range of 12 μm is desirable.

When the thickness exceeds 9 μm'cg, high resolution and excellent gradation reproducibility can be obtained, but when the thickness exceeds 13 μm, the resolution of fine characters decreases. If the thickness is less than 1 μm, fogging and toner scattering occur, making it impossible to obtain a clear image.

The structure of the carrier is as follows, and basically the materials listed as the constituent materials of the toner are used.

The carrier particles are mainly composed of magnetic particles and resin, and in order to improve resolution and gradation reproducibility, they are preferably spherical and have a weight average particle diameter of 50 μm, particularly 20 μm.
It is preferable to have a diameter of .mu.m or more and 40 .mu.m or less. If the carrier particle diameter exceeds 40 μm, particularly 50 μm, thinning of the developer layer is inhibited, developability deteriorates, and image quality deteriorates. If it is less than 20 μm, the developability, triboelectric chargeability, fluidity, etc. of the developer will be poor, and carrier scattering will likely occur.

In order to prevent the charge from disappearing, the carrier should have an insulating resistivity of 108 Ωcm or more, preferably 10'3 Ωcm or more, and more preferably 10'+Ωcan or more.

Such a carrier is made by coating the surface of a magnetic material with a resin, or by dispersing magnetic particles in a resin, and selecting the resulting particles using a known particle size selection means.

Further, to make the carrier spherical, proceed as follows.

■Resin-coated carrier: Select spherical magnetic particles.

■Magnetic powder dispersion carrier: After forming the dispersed resin, spherical treatment is performed using hot air or hot water, or spherical molecules tJ1. Form a resin.

It is preferable to mix the toner and carrier described above in such a ratio that the total surface area of each toner is equal.

For example, when the average particle size of the toner is 10 μm and the average particle size of the carrier is 20 μm, the toner concentration (weight ratio of toner to developer) is 5 to 40 wt%, preferably 8 to 2
It is appropriate to set it to 54%.

That is, in the developer of the present invention, unlike a conventional developer in which a large number of small particle size toners adhere to the outer periphery of a large particle size carrier, the particle size of the carrier is small and close to the particle size of the toner. Therefore, it is preferable that the mixing ratio is such that the total surface area of both is approximately equal.

Specific examples will be described below.

The irradiated original image is irradiated onto the image carrier 20 via the mirror 22 and the lens 23. In this way, an electrostatic latent image is formed. This electrostatic latent image is developed by a developing device H.

The thus obtained toner image is easily transferred by being neutralized by the exposure lamp 28 and then transferred to the recording paper P by the transfer pole 29. The recording paper P is transferred to the image carrier 2 by the separation pole 30. The image is separated from the image and fixed by the fixing device 31.

On the other hand, the image carrier 20 includes a removing electrode 32 and a cleaning device 3.
Cleaned by 3.

The cleaning device 33 is a row that collects cleaning blades.

In the image forming process in the copying apparatus shown in FIG. 4, development is performed using a developer having the following formulation, and image formation is performed under the image forming conditions shown in Table 1 below.

Table 1 Development conditions (regular development) Image carrier Se photoreceptor (100φ drum) Linear speed LOOmm/s Surface potential +800 V (dark area) ~
OV (bright part) Sleeve diameter 25mm Sleeve linear speed 25On+m/s (forward direction) Number of magnetic roll poles 8 poles Magnetic roll rotation speed 120Or, p, m.

Development gap 500 μm Developer layer thickness
400μm (maximum value) Developer toner concentration 12wt% Toner charge amount -1
5μc/g (average) Toner adhesion amount on sleeve 0
．． 3mg/cotDC bias 0~+1
00■AC bias 0.5~2KV,.

(2kllz) Parts by weight are shown in parts by weight, and particle sizes are shown as values determined by the BET method. In addition, the toner includes 1 part of 4 parts of mold release agent and 1 part of colorant (100 parts by weight of polyester resin).
10 parts by weight of carbon blank) was added. The carrier used had a core material of ferrite particles and was coated with a resin made by mixing methyl methacrylate and styrene at a weight ratio of 4:6, and had a magnetization of 27 emu/g, a specific resistance of 101 ffΩcm or more, and a specific gravity of 5. 2. Weight average particle size 30
It is μm. The above resistivity was determined by placing the particles in a container with a cross-sectional area of 0.50 cnl and tapping, then applying a load of l kg/ctA on the packed particles, f11
1000 V/between the electrode that also serves as a weight and the bottom in electrode.
This value is obtained by reading the current value when a voltage that generates an electric field of cm is applied. Moreover, the above-mentioned weight average particle diameter is a value measured with a Coulter Counter (manufactured by Coulter Inc.).

The condition of the image formed on the recording paper is shown in the third section below.
As shown in the table. In the same table, ◎ indicates extremely excellent, ○ indicates excellent, Δ indicates poor, and × indicates extremely poor.

As can be seen from Table 3, in all of the Examples, images with sufficient image density and resolution were obtained compared to the Comparative Examples, and were free of fog and carrier adhesion. Good results were obtained in all cases when the developing bias was within the range shown in Table 1. Further, even when the toner was operated for a long period of time while replenishing toner, the developability remained stable without major changes. Furthermore, there was very little contamination due to developer scattering inside the machine.

The above example is an example of regular development, but next, an example of reversal development will be described.

Same image forming device and developer image carrier as in the previous example Organic photoreceptor (140φ drum) Linear speed 60 mm/s Surface potential +700 V (non-exposed area)
, -50V (Exposed part) Sleeve diameter 20mm Sleeve linear speed 250mm/s (Forward direction) Number of magnetic roll poles 8 poles Magnetic roll rotation speed 1000r, p, m.

Development gap 500 μm Developer layer thickness
400μm (maximum value) Developer toner concentration 12wt% Toner charge amount -1
5μc/g (average) Toner adhesion amount on sleeve 0
．． 4n+g/cnl DC bias -50
0~-600■AC bias 0.5~2
．． 5 KV, -.

(2 kHz) The condition of the image formed on the recording paper was generally the same as in the case of regular development (see Table 3), and was of extremely high quality.

Next, an example using a developer to which a friction-reducing substance is added will be described.

Regular development was carried out under the conditions shown in Table 1 above using a developer having the composition shown in Table 5 below.

The conditions of the images formed on the margin recording paper are as shown in Table 6 below. The ◎ and ○ marks in the table are the same as those in Table 3 above.

The recorded images obtained were of excellent image quality, similar to the examples shown in Table 3 in which the developer was used without the addition of a friction-reducing substance.

Incidentally, when development was performed 50,000 times using the developer shown in Table 5, virtually no change in image density or resolution was observed. On the other hand, when the friction-reducing substance was not added and a developer having the same composition as in Example 11 was used,
A decrease in image density and resolution was observed after 500 times of development, and when 0.009 parts by weight of zinc stearate was added as a friction-reducing substance and a developer with the same composition as in Example 11 was used, the difference was observed after 2000 times of development. A decrease in image density and resolution was observed during development.

Further, when reversal development was carried out using the developer shown in Table 5 under the conditions shown in Table 4, almost the same results as those shown in Table 6 were obtained.

Regarding color image formation -jul Figure 5 (al indicates the structure of a multicolor image forming device, and a multicolor image is formed as follows. Note that the same components as in Figure 4 are The surface of the image carrier 20 is uniformly charged by a scorotron charger 27.The reading device IN then charges the original 25.
The CCD 24 built into the reading device IN detects an image of the blue color of the document, and this image information is converted into a signal suitable for recording by the image data processing section TR.

This signal is sent to the laser optical system 26 shown in FIG.
irradiated on top. In this way, an electrostatic latent image is formed. This electrostatic latent image is developed by a developing device H containing yellow toner. The image carrier 20 on which the toner image has been formed is uniformly charged again by the scorotron charging electrode 27 and subjected to green image exposure in the same manner as described above. The formed electrostatic latent image is developed by a developing device 1 containing magenta toner. As a result, a two-color toner image of yellow toner and magenta toner is formed on the image carrier 20. Thereafter, cyan toner and black toner are developed in a similar manner, and a four-color toner image is formed on the image carrier 20. The four-color toner image is charged by the charging electrode 28 and transferred to the recording paper P at the transfer pole 29. The recording paper P is separated from the image carrier 20 by the separation pole 30 and transferred to the fixing device 3.
It is fixed at 1. On the other hand, the image carrier 20 is cleaned by the removing electrode 32 and the cleaning device 33.

The cleaning device 33 has a cleaning blade 34 and a fur brush 35. These are kept out of contact with the image carrier 20 during image formation, and when a multicolor image is formed on the image carrier 20, they come into contact with the image carrier 20 and scrape off residual toner after transfer. Thereafter, the cleaning blade 34 is separated from the image carrier 20, and the fur brush 35 is separated from the image carrier 20 with a slight delay. The fur brush 35 functions to remove toner remaining on the image carrier 20 when the cleaning blade 34 leaves the image carrier 20.

In this multicolor image forming apparatus, one color is developed each time the image carrier 20 rotates, but each image exposure must start from the same position on the image carrier 20.

Further, during image formation, the developing device, each electrode other than the charging electrode 27, the paper feed, paper conveyance, and cleaning device 33, which are not used, do not act on the image carrier 20.

The laser optical system 26 is shown in FIG.
is a semiconductor laser oscillator, 3rd is a rotating polygon mirror, 39 is f
-θ lens.

The principle of this multicolor image forming apparatus will be explained with reference to the flowchart shown in FIG. FIG. 6 shows changes in the surface potential of the image carrier (photoreceptor), taking as an example the case where the charging polarity is positive. PH indicates the exposed area of the photoconductor, DA indicates the unexposed area of the photoconductor, and DUP indicates the increase in potential caused by the adhesion of the positively charged toner T to the pH of the exposed area during the first development.

The photoreceptor is uniformly charged by a scorotron charger and has a constant positive surface potential E as shown in (al).

Next, first image exposure is applied using a laser, cathode ray tube, LED, or the like as an exposure source, and as shown in FIG. 3(b), the potential of the exposed portion PH decreases in accordance with the amount of light. The electrostatic latent image thus formed is developed by a developing device to which a positive bias approximately equal to the surface potential E of the unexposed area is applied. As a result, as shown in (C), the positively charged toner T adheres to the exposed area PH, which has a relatively low potential, and the first toner image T1
is formed. In the area where this toner image T is formed, the potential is increased by DUP due to the adhesion of the positively charged toner T, but the potential does not become the same as that of the unexposed area DA. Next, the surface of the photoreceptor on which the first toner image has been formed is charged a second time by a charger, and as a result, the surface potential E becomes uniform regardless of the presence or absence of toner T. This is shown in (dl). A second image exposure is performed on the surface of this photoreceptor to form an electrostatic latent image ((e)), and as in (C1), the toner T is positively charged with a different color. The toner image T2 is developed and a second toner image is obtained. This is shown in (f). By repeating the above process, a multicolor toner image is obtained on the photoreceptor. This is transferred to recording paper. A multicolor recorded image is obtained by transferring and fixing this by heating or applying pressure.In this case, the photoreceptor is cleaned of residual toner and charges on the surface and used for the next multicolor image formation. .

On the other hand, apart from this, there is also a method of fixing a toner image on a photoreceptor.

In the method illustrated in FIG. 6, it is desirable that at least the developing step (f) be performed in such a way that the developer layer does not come into contact with the surface of the image carrier.

Note that in the multicolor image forming method, the second and subsequent charging steps can be omitted. If such charging is not omitted and charging is repeated each time, a static elimination step may be performed before charging. Furthermore, the exposure sources used for each image exposure may be the same or different.

In the multicolor image forming method, toners of four colors, for example, yellow, magenta, cyan, and black, are often superimposed on an image carrier for the following reason. According to the principle of the subtractive color method, a black image should be obtained by superimposing the three primary colors of yellow, magenta, and cyan, but the toners for the three primary colors in practical use do not have ideal absorption wavelengths. Moreover, due to misalignment of the toner images of the three primary colors, it is not only difficult to reproduce the clear black required for characters and lines using only these three primary color toners, but also the density is insufficient even in color images. I tend to do it. Therefore, as described above, a multicolor image is formed using four colors, which are the three primary colors plus black.

A time chart showing the driving relationship over time of each component constituting the multicolor image forming apparatus of FIG. 5 is as shown in FIG. 7.

Using such a multicolor image forming apparatus, multicolor images were formed under the image forming conditions shown in Tables 7, 8, and 9 below.

All developers have a weight average particle size of 30 μm and a coating layer thickness of 1 pr.
Contains a C, -Z, -based ferrite carrier with a saturation magnetization of 30 emu/g, and the toner colorants include Hengejin SA 6 bodies for the yellow toner, Rhodamine B lake for the magenta toner, Phthalocyanine derivatives are used for cyan toner. The rest of the developer was the same as the developer used in the monochromatic image formation example.

Note that the transfer is performed by a corona discharge method, and the fixing is performed by a heat roll method.

Table 8 The multicolor image formed as described above had uniform image quality with no color difference in the solid image area.

Note that the order of toner image formation is not limited to the above, and may be, for example, the order of black, yellow, magenta, and cyan.

FIG. 8 shows a multicolor image forming apparatus in which a multicolor image is formed during one rotation of an image carrier. The difference from the device in Fig. 5 is (11 charging electrodes between each developing device, 27C127D
and image exposure system (semiconductor laser -) 26B, 26G, 26
Provision of D (2) The cleaning device is only for transporting the grade 34 and toner (3) paper.

For example, when forming a four-color image, the linear velocity is the same as in the previous example.
, image formation is completed approximately four times faster than the apparatus shown in FIG.

Other than the above, there is no difference from the process using the apparatus shown in FIG.

Using the multicolor image forming apparatus shown in FIG. 8, multicolor images were formed under the conditions shown in Table 10 below. Other conditions are as stated in Section 5 above.
There is no difference from the embodiment using the device shown in the figure.

The obtained polychromatic image was of extremely high quality as in the example using the apparatus shown in FIG. 5 above.

The present invention can also be preferably applied to an apparatus capable of forming a multicolor image on a photoreceptor by performing image exposure once. The apparatus performs multicolor image formation as described below using a photoreceptor preferably provided with an electrically conductive member, a photoconductive layer, and an insulating layer including a filter layer consisting of a plurality of different types of filters.

That is, by applying electrical charge and imagewise exposure to the surface of the photoreceptor, an image is formed based on the charge density at the interface between the insulating layer and the photoconductive layer, and by exposing the entire surface of the image forming surface to specific light, the image of the photoreceptor is A potential pattern is formed on the filter portion, and the potential pattern is developed by a developing device containing toner of a specific color to form a monochrome toner image. Next, after the potential pattern is smoothed by charging, a potential pattern is formed by full-surface exposure different from the previous one, and development is performed using a developing device that stores toner of a different color than the previous one, so that two toners are formed on the photoreceptor. A colored toner image is formed. Thereafter, potential smoothing, full-surface exposure, and development are repeated as many times as necessary. In this development, a non-contact developing means is employed at least from the second time onwards. As a result, toner of different colors adheres to each filter portion of the photoreceptor, forming a multicolor image (Japanese Patent Application No. 59-83096,
(See No. 59-187044, No. 59-185440, No. 60-229524). According to this multicolor image forming apparatus, only one image exposure is required, so there is no risk of color shift occurring.

The photoreceptor (image bearing member) assembled into such a multicolor image forming apparatus is, for example, a cross-sectional view shown in FIG. 9(a) and a cross-sectional view shown in FIG.
As shown in the plan view, it has a structure in which a photoconductive layer 42 and an insulating layer 43 are sequentially laminated on a drum-shaped conductive substrate 41. The color separation filter portions of R) are arranged in a mosaic pattern.

In addition, the photoreceptor has a structure in which a filter is provided on the side of the field-sensitive substrate, and image exposure and full-scale exposure are performed from the filter side (Japanese Patent Application No. 1986-1
No. 99547) and other configurations (Patent Application No. 59-2010)
No. 84) can also be taken.

Further, the photosensitive layer is not limited to a single layer, and may have a functionally separated structure consisting of a charge generation layer and a charge transfer layer. (Tokugan Sho 6
0-245178) In addition, the photoreceptor has a color separation function in the photosensitive layer (Japanese Patent Application No. 5
No. 9-201085, Japanese Patent Application No. 60-245177).

When a multicolor image was formed using such a multicolor image forming apparatus according to the developing method according to the present invention, a multicolor image with excellent image quality was obtained in the same way as in the above-mentioned multicolor image formation embodiment. The image was obtained.

As described in detail of the present invention, the following effects can be achieved by using the developing method based on the present invention.

(1) Since the toner used has an average particle diameter of 7 to 20 μm according to the BET method and has been treated with a fluidizing agent of 0.1 to 1.0 parts by weight per 100 parts by weight of the toner, the toner and carrier are In addition to reducing the adhesion force between the carrier and toner to make it easier for the toner to fly during development, there is also an appropriate amount of 15! between the carrier and toner. Frictional electrification is applied, and as a result, high image density can be obtained even with toner having a small particle size as described below, and fogging and contamination within the image forming apparatus are also prevented.

(2) Since the weight average particle diameter of the toner is as small as 6 to 20 μm, a clear visible image with poor resolution and gradation reproducibility is formed.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and FIG. 1 is a sectional view of the developing device, FIG. 2(a) is a perspective view of the stirring member, and FIG. is a graph showing the relationship between the gap between the developer thin layer regulating member and the developer transport carrier (sleeve) and the amount of developer transported; Figure 4 is a schematic diagram of a monochromatic image forming apparatus; Figure 5 (a) is Schematic diagram of the multicolor image forming apparatus (bl is a schematic diagram of the laser optical system, Figure 6 is a flowchart for explaining the process of forming a multicolor image, Figure 7 is a diagram of the apparatus for forming a multicolor image) 8 is a schematic diagram of another multicolor image forming apparatus, and FIG. S shows an example of the structure of a multicolor image forming image (1 unit); al is a sectional view, and tb+ in the same drawing is a plan view. In addition, in the reference numerals shown in the drawings, 3-.
4------...-1---Magnetic roll 5---------
-1 Developer thin layer forming member 7.8-1--. One image carrier 26-----------Laser optical system 27--
・−1111−−・・Charger 41−−−−−−
- Conductive substrate 42 - - Photoconductive layer 43 - Insulating layer Hll, J, - Development device D - -・
--- Developer T, T, , T2 --- 1-ner. Agent Patent Attorney Hiroshi Aisaka Figure 3
5 Gap (mm) Figures 4, 2, and 5 (spontaneous) Procedure Nein Official Book August 7, 1985 Commissioner of the Patent Office Black 1) Yu Akira, 1986 Patent Application No. 21655 2, Title of the Invention Developing method of electrostatic latent image 3, relationship with the case of the person making the amendment Patent applicant address: 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name:
(127) Konishi Rokusha y4 Kogyo Co., Ltd. 4, Agent Address: 2-4-11 Shibasaki-cho, Tachikawa-shi, Tokyo FINE Building Equipment O425-24-5411it 8, Amendment due to the invention increasing due to the addition of 6.7 di. (13) Of the drawings attached to the application, Figure 7 is corrected as shown in the attached sheet. Indication of 1986 Patent Application No. 021655 2 Name of the invention Method for developing electrostatic latent images 3 Relationship with the case of the person making the amendment Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name name
(127) Konishiroku Photo Industry Co., Ltd. 4, Agent address: FINE Building Equipment 0425-24-5411f, 2-4-11 Shibasaki-cho, Tachikawa-shi, Tokyo (1), Line 5 on page 12 of the specification [ It is impossible and j is
I am correcting it to "Impossible." One or more -

Claims (1)

[Claims] 1. When an oscillating electric field is generated in the development area and the electrostatic latent image formed on the image carrier is developed with a developer layer containing a carrier and toner on a developer transport carrier, the developer layer is made into a thin layer, and BET Using a toner having an average particle size of 7 to 20 μm according to the method and containing 0.1 to 1.0 parts by weight of a fluidizing agent per 100 parts by weight of the toner, the weight average particle size of the toner is 6 to 20 μm. A method for developing an electrostatic latent image.