JPS59222853A - Developing method - Google Patents

Abstract

PURPOSE:To enable excellent development in all environments by using a two- component developer consisting of a toner for press fixing and a magnetic carrier, specifying respectively the space between the surface of a developer conveying carrier and the surface of a latent image carrier and the thickness of a toner layer and impressing an oscillating electric field on a developing part. CONSTITUTION:Development is accomplished by regulating the two-component developer D consisting of a toner for press fixing and a magnetic carrier by a blade 4 in such a way that thickness of the developer layer is made thinner than the space in the developing region A between the surface 1 of an image carrier and the surface of a developer conveying carrier sleeve 2. The toner particles T are preferably spherical and have <=20mu average grain size and the carrier particles have preferably <=50mu average grain size. An oscillating electric field of AC and DC is impressed between the image carrier 1 and the sleeve 2 from a power source 10 to vary the magnetic field with time, thereby oscillating the developing layer. The image which can reproduce faithfully fine lines, dots, varying densities, etc. is thus obtd. by using the fine particle toner and carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for developing an electrostatic latent image or a magnetic latent image in an electrophotographic copying apparatus, etc., and more specifically, the present invention relates to an improvement in a method for developing an electrostatic latent image or a magnetic latent image in an electrophotographic copying apparatus, etc. So-called magnetic brush development, in which a mixed two-component developer is supplied to the surface of a developer transport carrier to form a developer layer on the developer transport carrier, and the latent image on the image carrier surface is developed with the developer layer. Concerning improvements in methods.

[Prior art]

First, as an example, an outline of a developing method in an electrophotographic copying apparatus will be explained. Regarding this, in the general magnetic brush development method using a two-component developer, it is relatively easy to control the triboelectric charging of toner particles, and the agglomeration of toner particles occurs, and the magnetic brush stands up easily. It has excellent abrasion properties on the surface of the image carrier and has sufficient leaning effects even when used for cleaning.
It is widely used despite the need to control the amount of toner particles relative to carrier particles. Conventionally, this developing method generally uses a two-component developer consisting of magnetic carrier particles with an average particle diameter of several tens to hundreds of micrometers and toner particles for heat fixing with an average particle diameter of more than ten micrometers. ing. Instead of toner particles for heat fixing, toner particles for pressure fixing, which can be easily fixed on recording paper without the need for heating means, can be used, and a carrier that triboelectrically charges toner particles can be used. During agitation with particles, toner particles tend to settle on the surface of carrier particles, or toner particles tend to aggregate together. Since the toner particles are strongly rubbed, there is a problem in that the adhesion between the toner particles and the carrier particles becomes even stronger.

Furthermore, because the toner particles and carrier particles of the developer are coarse, it is difficult to obtain high-quality images that reproduce delicate lines, dots, and differences in shading using conventional magnetic brush development methods. That is, in order to obtain high-quality images using this developing method, many efforts have been made in the past, such as resin coating of carrier particles, improvement of the magnet in the developer transport carrier, and study of the bias voltage for the developer transport carrier. However, the reality is that stable and fully satisfactory images still cannot be obtained.

Therefore, in order to obtain high-quality images, if the average toner particle diameter is 20 μm or less, especially fine particles of 10 μm or less, ■ the influence of van der Waals force will be large relative to the Coulomb force during development. , so-called fogging occurs in which toner particles adhere to the ground area of the image background, and it is difficult to prevent fogging even by applying a DC bias voltage to the developer transport carrier. ■ Frictional charging control of toner particles It becomes difficult and agglomeration is more likely to occur. On the other hand, as the carrier particles are made finer, (2) the carrier particles also come to adhere to the electrostatic image area of the image carrier. The reason for this is considered to be that the force of the magnetic bias has decreased and the carrier particles have adhered to the image bearing member together with the toner particles. Note that as the bias voltage increases, carrier particles also begin to adhere to the ground portion of the image background. A problem with micronization is that the side effects mentioned above are more noticeable and clear images cannot be obtained, so it is difficult to actually use micronization of toner particles and carrier particles. there were.

[Purpose of the invention]

The present invention allows toner particles to be easily fixed on recording paper, prevents toner particles from being fixed to carrier particles or agglomerated, and furthermore allows the use of fine particles of toner and carrier. The present invention provides a method for developing an electrostatic latent image or a magnetic latent image that can faithfully reproduce lines, points, shading differences, etc.

[Structure of the invention]

The present invention provides a method in which a two-component developer layer consisting of toner particles and magnetic carrier particles is formed on the surface of a developer transporting member, and an image on the surface of the image bearing member is developed by the developer layer, in which the toner particles are fixed under pressure. A developing method characterized in that the toner particles of the present invention are used, and the development is performed under an oscillating electric field.

Hereinafter, the present invention will be described with reference to a case where an electrostatic image formed on an image carrier such as a photoreceptor is developed.

In the present invention, toner particles for pressure fixing used in a two-component developer are 20 to 9/a with a pressure roller for fixing.
Conventionally known pressure fixing toner coarse particles are used, which become fixed on the recording paper when applied with a linear pressure of about n. Such toner particles include polyolefins, ethylene-vinyl acetate copolymers, polyurethane, adhesive resins such as rubber, fatty acid waxes such as valmitic acid and stearic acid, coloring components such as carbon, and optionally Added charge control agents, etc., or in the case of magnetic toner, metals such as iron, chromium, nickel, and cobalt, or compounds and alloys thereof, such as triiron tetroxide, γ
- Ferric oxide, chromium dioxide, manganese oxide, ferrite, manganese - Those consisting of particles containing dispersed fine particles of ferromagnetic or paramagnetic substances such as copper-based alloys, such as those with good adhesive properties. It is known that the particles are made of microcapsule type particles whose outer surface is coated with a highly chargeable resin (which may contain a coloring component, etc.) such as is used in ordinary heat fixing toner particles. . Particularly preferred in the present invention are spherical dispersed toner particles and microcapsule toner particles in which the above-mentioned highly adhesive particles are formed into spherical shapes by a spray drying method, a 70-coater method, a granulation polymerization method, or the like. . Note that the spheroidizing treatment in the flow coater method may be performed using hot air or hot water. When such spherical toner particles are used, the fluidity of the toner particles is improved, and the toner particles are firmly attached to the carrier particles9, and the occurrence of agglomeration among toner particles is significantly eliminated. Charging due to friction with carrier particles has also become effective, and therefore only toner particles are selectively applied to the electrostatic image from a developer layer formed with carrier particles at an appropriate toner concentration. At the same time, the transfer efficiency and fixing performance from the surface of the image carrier to the recording paper are improved.

This is because the spherical shape of the toner particles reduces the contact area between the toner particles and the carrier particles and between the toner particles and the surface of the image carrier, reducing non-uniform forces that are difficult to control, such as van der Waals forces. This is thought to be related to the fact that there is less charge concentration or discharge neutralization caused by needle-like protrusions, edges, or elongated shapes, and that the contact pressure with the recording paper is higher. For that,
Preferably, the toner particles are spherical so that the ratio of the major axis to the minor axis is at least 3 times or less.

Further, magnetic toner is preferably used in the present invention, and
, the amount of magnetic fine particles in the toner particles is 60 wt% or less,
In particular, it is preferably used that does not exceed 30 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, so that the uniformity of the developer layer is further improved. Moreover, the occurrence of fogging is prevented, and scattering of toner particles is also less likely to occur. However, if the amount of magnetic material contained is too large, the magnetic force between the carrier particles and the carrier particles becomes too large, making it impossible to obtain a sufficient developing density. As a result, frictional charging control becomes weaker, toner particles are more likely to be damaged, and toner particles are more likely to aggregate with carrier particles.

In addition, the toner particles used in the present invention have an average particle diameter of 20 μm or less, particularly 10 μm or less, so that high-quality images can be obtained.
It is preferable that it is less than μm.

As the average particle size of the toner increases, as described above, the roughness of the image becomes noticeable. Normally, toner with an average particle size of about 20 μm is not a practical problem for developing fine lines arranged at a pitch of 10 lines/thickness, but if a finely divided toner with an average particle size of 10 μm or less is used, The resolution has been significantly improved, and development can be performed that faithfully reproduces the differences in shading. Such toner particles can be obtained by sorting the toner particles obtained by the method described above using a known average particle size sorting means, if necessary. However, in general, when the average particle size of toner particles is reduced, it becomes easier to reproduce delicate lines, dots, and differences in shading, but on the other hand, the amount of triboelectric charge qualitatively decreases in proportion to the square of the particle size. On the other hand, adhesion forces such as van der Waals forces become relatively strong, causing the toner particles to separate from the carrier particles and become K Then, it cannot be easily removed by rubbing with a magnetic brush, causing fogging. In the conventional magnetic brush development method, this problem became noticeable when the average particle size of toner particles became 10 μm or less.

This is also one of the reasons why toner particles for pressure fixing are not used as toner particles in conventional magnetic brush development methods.

The present invention mainly performs development under an oscillating electric field, thereby solving the above-mentioned problems caused by using toner particles for pressure fixing as toner particles of a two-component developer, and the above-mentioned problems when toner particles are made into fine particles. I'm trying to solve the problem. That is, the toner particles attached to the developer layer are easily transferred from the developer layer to the image area or non-image area on the image carrier surface by electrically applied vibrations, and are not easily separated. When the developer layer rubs the surface of the image carrier, toner particles attached to the non-image area of the image carrier can be easily removed or moved to the electrostatic image area, and the developer layer When the layer thickness is made thinner than the gap between the image carrier surface and the developer transport carrier, the migration of toner particles with a low charge amount to the image area or non-image area is significantly reduced, and the friction with the image carrier surface is reduced. As a result, toner particles with particle diameters of about 1 μm have come to be used, as toner particles no longer adhere to the image carrier due to frictional electrification. Therefore, it is possible to obtain a clear toner image with good reproducibility in which the electrostatic latent image is faithfully developed. Further, since the oscillating electric field weakens the bond between toner particles and carrier particles, adhesion of carrier particles accompanying toner particles to the image bearing surface is also reduced. The effect of development under an oscillating electric field becomes more pronounced when spherical toner particles are used. However, especially when the thickness of one developer layer is made thinner than the gap between the image carrier surface and the developer transport carrier surface, toner particles with a large amount of charge vibrate under the oscillating electric field in the image area and non-image area. However, depending on the strength of the electric field, the carrier particles also vibrate, and the toner selectively moves to the electrostatic image area on the image carrier surface, so the adhesion of the carrier to the image carrier surface is greatly reduced. Ru. Further, in order for the toner particles to follow the electric field, it is desirable that the amount of charge of the toner particles be greater than 1 to 3 μC/2 (preferably 3 to 300 μC/2). In particular, when the particle size is small, a high amount of charge is required.

Before describing the specific preferred development conditions, preferred conditions for the carrier particles of the developer used in the present invention will be described.

In general, in the carrier of a two-component developer, if the average particle size of the magnetic carrier particles is large, the condition of the developer layer formed on the developer transport carrier becomes rough, and the electrostatic image is not processed while being vibrated by an oscillating electric field. Even after development, unevenness tends to appear in the toner image, and the toner concentration in the @developer layer becomes low, causing problems such as high-density development is no longer possible. K can solve the problem (2) by reducing the average particle size of the carrier particles, and as a result of experiments, its effect begins to appear at 50 μm or less, and when it becomes 30 μm or less, the above problem (2) actually occurs. It turned out to be gone. Further, the above-mentioned problem @ is also solved by making the magnetic carrier particles finer, which increases the toner concentration in the developer layer, allowing high-density development to be performed. On the other hand, if the carrier particles are too fine, they may adhere to the surface of the image bearing member along with the θ toner particles, or O may be easily scattered. These phenomena are also related to the strength of the magnetic field acting on the carrier particles and the resulting magnetization strength of the carrier particles, but generally, the average particle diameter of the carrier particles is 15 μm.
When the thickness is less than 5 μm, a tendency gradually begins to appear, and becomes noticeable when the thickness is 5 μm or less. Then, some of the carrier particles adhering to the surface of the image carrier are transferred onto the recording paper together with the toner.
They are removed from the surface of the image carrier along with the remaining toner, but with conventional carrier particles made only of magnetic material, (1) the carrier particles that have migrated onto the recording paper are not fixed to the recording paper by themselves, so they easily fall off. Another problem is that when the carrier particles remaining on the surface of the O image carrier are removed by a cleaning device, the surface of the image carrier made of a photoreceptor is easily damaged.

The above-mentioned problem of O to θ which occurs when a particularly finely divided carrier is used can be solved by forming magnetic carrier particles from a resin or the like and magnetic particles. This is because the magnetic carrier particles are formed with a resin or the like that can be fixed to the recording paper together with the toner particles, so that even if they adhere to the recording paper, they are fixed together with the toner particles by pressure. It's for a reason. Furthermore, since the magnetic carrier particles contain a resin or the like, the surface of the image carrier will not be damaged when the magnetic carrier particles are removed from the surface of the image carrier together with residual toner by a cleaning device. Therefore, even if the carrier particles have an average particle size of 15 to 5 μm or less, the problem of θ does not actually cause any trouble. Note that if carrier adhesion occurs, it is effective to provide a recycling mechanism. Furthermore, the fact that the carrier particles are spherical improves the agitation performance of the toner and carrier and the transportability of the developer, and makes it difficult for toner particles to coagulate among themselves or toner particles and carrier particles to aggregate.

From the above, the appropriate conditions for the carrier are that the average particle diameter of the magnetic carrier particles is preferably 50 μm or less, particularly preferably 3 μm or less.
0 μm or less, the magnetic carrier particles are formed together with a substance that can be fixed to the recording paper, such as resin, and furthermore,
It is spherical.

For such magnetic carrier particles, spherical magnetic particles with the same resistance as in magnetic toners are selected, or spherical magnetic particles are selected from resins or waxes similar to those in toners, especially spherical magnetic particles. Styrene resin, vinyl resin, and ethyl resin are conventionally known as coating materials.

Spherically coated with resin such as rosin-modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, etc., or resin with charge control agent added as necessary, or containing dispersed magnetic particles. It can be obtained by making spherical particles of resin or wax, and the same method used for toners using hot air or hot water can be applied to make the particles spherical, or in the case of dispersed particles, the spray drying method can also be used. As for the average particle size, a preferable carrier can be obtained by selecting the average particle size using a conventionally known average particle size selection means, if necessary.

In addition to the above-mentioned effects, making the carrier particles spherical with a resin or the like as described above makes the developer layer formed on the developer transport carrier uniform, and also makes the developer layer formed on the developer transport carrier uniform. It also has the effect of making it possible to apply a high bias voltage to the. That is, the fact that the carrier particles are made spherical by a resin or the like is because (1) Generally, carrier particles tend to be magnetized and attracted in the long axis direction, but by sphericalization, this directionality is lost, and therefore the developer layer becomes uniform. (2) In addition to increasing the resistance of the carrier particles,
There are no edges as seen in conventional carrier particles, and the electric field does not concentrate on the edges. As a result, even when a high bias voltage is applied to the developer transport carrier,
This provides the effect that discharge on the surface of the image carrier will not disturb the electrostatic latent image or breakdown of the bias voltage will occur. The fact that this high bias voltage can be applied means that when the development under an oscillating electric field in the present invention is performed by applying an oscillating bias voltage, the effect can be fully exhibited. That's what I'm saying. In addition, as mentioned above, wax is also used to make the carrier particles spherical, which produces such an effect, but from the viewpoint of the durability of the carrier, it is preferable to use resin.
In particular, it is preferable to form insulating magnetic particles so that the resistance is 1015 Ωα or more. This resistivity was determined by placing the particles in a container with a cross-sectional area of 0.50 cIn2, tapping them, applying a load of I Kg/crn2 on the packed particles, and applying a voltage of 100 OV/3 between the load and the bottom electrode. This value is obtained by reading the current value when a voltage that generates an electric field is applied. If this value is low, when a bias voltage is applied to the developer transport carrier, charges will be injected into the carrier particles, causing the image to be Carrier particles tend to adhere to the body surface, or bias voltage breakdown tends to occur.

In summary, magnetic carrier particles are spherical so that the ratio of the long axis to the short axis is at least 3 times or less, and therefore, the magnetic carrier particles are spherical in shape, so that charge concentration and discharge occur at needle-shaped parts and edge parts. Appropriate conditions are that there are no protrusions that are likely to cause corrosion, and that the resistivity is 106 Ω or more, preferably 1015 Ω or more, and such magnetic carrier particles can be obtained by the Hiko method as described above.

In the developing method of the present invention, a developer in which spherical toner particles and carrier particles, particularly preferably spherical carrier particles, as described above are mixed in the same proportion as in a conventional two-component developer is preferably used. However, if necessary, a fluidizing agent to improve the fluidity and sliding of the particles, a cleaning agent to clean the surface of the image bearing member, and the like are mixed.

As a fluidizing agent, colloidal silica, silicon face, metal soap, or a nonionic surfactant can be used, and as a cleaning agent, a fatty acid metal salt, organic group-substituted silicon, or a surfactant such as fluorine can be used. Can be done.

Next, preferred developing conditions for forming such a developer layer on the developer transport carrier and developing the electrostatic image on the image carrier will be specifically described.

The developer transport carrier that forms the developer layer is the same developer transport carrier used in conventional development methods to which a bias voltage can be applied. A structure in which a rotating magnet body having a plurality of magnetic poles is provided inside is preferably used. In such a developer transport carrier, the rotation of the rotating magnet causes the developer layer formed on the surface of the sleeve to move in an undulating manner, so that new developer is successively supplied and the sleeve Even if there is some degree of non-uniformity in the layer thickness of the developer layer on the surface, the effect of this is sufficiently covered by the above-mentioned wave-like movement so that it does not become a problem in practice. It is preferable that the developer conveying speed due to the rotation of the rotating magnet or the rotation of the sleeve is almost the same as or faster than the moving speed of the image carrier. Note that it is preferable that the rotating magnet body and the sleeve are conveyed in the same direction by rotation. In the case of the same direction, image reproducibility is better than in the opposite direction. However, it is not limited to these.

In addition, the thickness of the developer layer formed on the developer transport carrier is
It is preferable that the thickness is such that the adhered developer is sufficiently scraped off by the thickness regulating blade to form a uniform layer.
The gap between the developer transport carrier and the image carrier is several 10
~2000 μm is preferred. When the surface gap between the developer transport carrier and the image carrier becomes narrower than several tens of micrometers, it becomes necessary to form magnetic brush ears that uniformly develop the gap, and it becomes necessary to form sufficient toner particles in the developing area. If the gap greatly exceeds 2000 μm, the opposing electrode effect will decrease and sufficient development density will not be obtained, and the electrostatic image The edge effect, in which more toner adheres to the contour than the center of the image, also increases. In this way, when the gap between the developer transport carrier and the image carrier becomes extreme, it becomes impossible to make the thickness of the developer layer on the developer transport carrier appropriate.
In contrast, in the range of 000 μm, the developer layer is
can be formed appropriately. Therefore, it is particularly preferable to set the gap and the thickness of the developer layer to conditions such that the developer layer does not come into direct contact with the surface of the image carrier, but comes as close as possible. This prevents scratches caused by rubbing of the developer layer in toner development of an electrostatic image, and fogging from occurring.

Furthermore, development under an oscillating electric field is preferably carried out by applying an oscillating bias voltage to the sleeve of the developer transport carrier without providing a new electrode member. Further, it is preferable to use a bias voltage that is a combination of a direct current voltage that prevents toner particles from adhering to non-image areas and an alternating current voltage that makes it easier for the toner particles to separate from the carrier particles.

An oscillating electric field is formed between the grounded image carrier substrate and the sleeve. However, the present invention is not limited to the method of applying an oscillating voltage to the sleeve or the method of applying a superimposed voltage of DC and AC.

The developing method of the present invention as described above is shown in FIGS.
It is implemented by an apparatus such as that illustrated in the figure.

1 to 3, 1 is a drum-shaped image carrier made of a photoreceptor such as Se, which rotates in the direction of the arrow and has an electrostatic image formed on its surface by a charging exposure device (not shown); 2 is aluminum; The sleeve 3 is made of a non-magnetic material such as a magnet body and has a plurality of N and S magnetic poles on its surface in the circumferential direction. The sleeve 2 and the magnet body 3 form a developer transport carrier. It consists of The sleeve 2 and the magnet body 3 can rotate relative to each other, and the figure shows that the sleeve 2 rotates in the direction of the arrow. Also,
The ON and S@ poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss, and the magnetic force forms a developer layer, ie, a magnetic brush, as described above on the surface of the sleeve 2. 4 is a regulating blade made of magnetic or non-magnetic material that regulates the height and amount of the magnetic brush; 5 is a cleaning blade that removes the magnetic brush that has passed through the developing area A from above the sleeve 2; Since the surface of the sleeve 2 comes into contact with the developer reservoir in the developer reservoir 6, the developer reservoir is thereby supplied, and the developer reservoir 7 stirs the developer reservoir to make the components uniform. This is a stirring screw. The developer reservoir 6 has a button so that the toner particles therein are consumed when development is performed, so 8 is a toner dropper for replenishing the toner particles T as described above, and 9 is a developer. It is a supply roller having four parts on its surface which drops toner particles T into a reservoir 6. 1o is protective resistance 11
This is a bias power supply that applies a bias voltage to the sleeve 2 via the sleeve 2.

The difference between the devices shown in FIGS. 1 to 3 is that in the device shown in FIG. 1, the sleeve 2 rotates in the direction of the arrow, and the magnet body 3 rotates in the opposite direction, so that While the magnetic flux densities of the S magnetic poles are approximately equal, in the device shown in FIG. 2, the sleeve 2 rotates in the direction of the arrow, but the magnet body 3 is fixed, and in the device shown in FIG. The magnetic flux densities of the N and S magnetic poles of the fixed magnet body 3 are not the same,
The magnetic flux density of the N magnetic pole facing the image carrier IK is the other N.

The magnetic flux density is larger than that of the S magnetic pole. Note that the magnetic pole facing the image carrier 1 is N as shown in the third figure.
Of course, the magnetic poles may be arranged side by side and facing each other, or the N and S magnetic poles may be arranged side by side and opposed to each other. By arranging a plurality of magnetic poles to face each other in this manner, it is possible to obtain the effect that development is more stable than when a single pole is posed to face each other.

In the apparatus described above, when the sleeve 2 is set so that the surface gap with the image carrier 1 is in the range of several tens to 2000 μm, and the electrostatic image on the image carrier 1 is developed, the sleeve 20 The magnetic brush formed on the surface of the sleeve 2
Alternatively, as the magnetic flux density on the surface of the magnet 3 changes as it rotates, it moves on the sleeve 2 while vibrating, thereby stably and smoothly passing through the gap with the image carrier 1. At this time, a uniform developing effect is imparted to the surface of the image carrier 1, making it possible to stably develop with a high toner density. To do this, in order to prevent the occurrence of fogging and to improve the developing effect, an oscillating bias voltage is applied to the sleeve 2 by a bias power supply 10, the base 1a of the image carrier 1 is grounded, and the sleeve 2 and the image carrier are An oscillating electric field is formed between the bodies 1. As mentioned above, this bias voltage is preferably a superimposed voltage of 1/'1 DC voltage and AC voltage.The DC component prevents fogging, and the AC component causes the magnetic brush to vibrate. 5
A voltage of 0 to 600v is used, and the AC voltage component is 10
0 f(z ~10 kHz, frequency 1~5 k
A frequency of Hz is used. Note that if the DC voltage component is too low, the effect of imparting vibrations will not be obtained, and if it is too high, the developer will not be able to follow the vibrations of the electric field, resulting in a decrease in developer density and the ability to obtain clear, high-quality images. There is a tendency to become less able to do so. In addition, the voltage value of the AC voltage component is also related to the frequency, but the higher the voltage value, the more the magnetic brush will vibrate and the more effective it will be. It also makes dielectric breakdown more likely to occur. However, if the carrier particles in the developer are made spherical by resin etc., dielectric breakdown can be prevented.
The occurrence of fogging can also be prevented by using the DC voltage component. Note that the surface of the sleeve 2 to which this AC voltage is applied may be insulated or coated with a resin or oxide film.

As described above, FIGS. 1 to 3 show an example in which an oscillating bias voltage is applied to the developer transport carrier, but the developing method of the present invention is not limited thereto. Even if several electrode wires are stretched and a vibrating voltage is applied thereto, the developer layer on the developer transport carrier is vibrated and the developing effect can be improved. In that case, a DC bias voltage is applied to the developer transport carrier,
Alternatively, oscillating voltages with different frequencies may be applied. Furthermore, the method of the present invention can be similarly applied to reversal development and the like. In that case, the DC voltage component is set to a voltage approximately equal to the reception potential in the non-image background portion of the image carrier. Furthermore, the method of the present invention is equally applicable to the development of magnetic latent images when using magnetic toner particles.

The present invention uses a two-component developer consisting of toner particles for pressure fixing and carrier particles as described above, and performs development under an oscillating electric field under the above-mentioned development conditions. We have solved the drawback that toner particles for pressure fixing tend to stick to carrier particles or aggregate, and have also made it possible to make toner particles and carrier particles finer, making it easier to fix toner images on recording paper. Therefore, specific embodiments of the present invention will be described next.

〔Example〕

Example 1゜ Toner particles contain 1 o of ethylene vinyl acetate copolymer.

Parts by weight, 10 parts by weight of carbon black, 5 parts by weight of nigrosine, pulverized and granulated, using non-magnetic particles with an average particle size of 10 μm formed into a spherical shape by a flow coater method. 30 μm 1 magnetization is 50 e
By using spherical ferrite particles coated with styrene-acrylic resin having a resistivity of about 1014 Ωα and a resistivity of about 1014Ωα, the toner ratio in the developer reservoir 6 of the developing device shown in FIG. Development was carried out under conditions such that the content of the carrier was 10 wt%. The average charge amount of the toner was 15 μC/g.

The image carrier 1 in this case is an OdS photoreceptor, and its peripheral speed is 18
0 mtn/se○, the maximum electrostatic image formed by the image carrier IK is -5o6v, the outer diameter of the sleeve 2 is 30, its rotation speed is 1100 rpm, the magnetic flux density of the N and S magnetic poles of the magnet body 3 is 900 Gauss, the rotation speed is 1000 rpm % Thickness of the developer layer 6, gap Q between the sleeve 2 and the image carrier 1, 5 mm, i.e. 500 μm 1 The bias voltage applied to the sleeve 2 is DC voltage component -250μ, AC Voltage component 1.
The frequency was 5 kHz and 500 V.

The image was developed under the above conditions, transferred to plain paper using a corona discharge transfer device, and fixed by passing it through a pressure fixing device using a calendar roller at a linear pressure of 20 and a pressure of 5 I/cIIL. The toner image on the recording paper had good fixation, no edge effects or fogging, and was extremely clear with high density.Even after 50,000 sheets of recording paper were obtained, the toner image remained stable from beginning to end. I was able to get no image.

Example 2 The same non-magnetic particles as in Example 1 were used except that the average particle diameter was 5 μm for the toner particles, and the carrier particles contained 50% fine ferrite particles with an average grain size of 2 μm in the same resin as the toner. Dispersed in wt%, kneaded, crushed and then sphericalized by hot air, the average particle size is 20 μm 1 magnetization is 3
Using particles with a resistivity of 0 emu/fl and a resistivity of 1014 Ωα or more, development was carried out using the developing device shown in FIG. 3 under conditions such that the toner ratio in the developer reservoir 6 was 5 wt% with respect to the carrier. went. The average charge amount of the toner was 30 μC/y.

In this case, the conditions of the image carrier 1 are the same as in Example 1, and the outer diameter of the sleeve 2 is also 3ON1, but the rotation speed is 150 rpm.
%The magnetic flux density of the magnetic pole facing the development area A of the magnet body 3 is 1
200 Gauss, developer layer thickness Q, 5 mg.

Gap between sleeve 2 and image carrier 1: 0.7 M, i.e. 700
The bias voltage applied to μm1 sleeve 2 has a DC voltage component of -200 V' and an AC voltage component of 2 kHz, 100 V'.
It was set to 0■.

The image was developed under the above conditions, transferred to plain paper by corona discharge, and fixed under the same conditions as in Example 1. It was extremely clear, with no dark spots, and had a high density.I subsequently produced 50,000 sheets of recording paper, and was able to obtain a stable and unchanging image from beginning to end.

Embodiment 3 Using the same toner and carrier as in Embodiment 2, a developing device similar to that shown in FIG. The ratio of toner particles in the developer to carrier particles is 5.
Development was carried out under conditions such that wt%. The average charge amount of the toner was 30 μC/1.

The conditions for the image carrier 10 in this case are the same as in Example 41, and the outer diameter of the sleeve 2 is also 3Q1n+x, but the number of rotations is 100.
rpm, N, magnetic flux density of S pole is 700 Gauss, its rotation speed is 500 rpm, developer layer thickness Q, 6 mtn
, the gap Q between the sleeve 2 and the image carrier 1 is 7 mm, that is, 70 mm.
0μm, the bias voltage applied to the sleeve 2 is DC voltage component -200μ, AC voltage component 2kHz, 100
It is 0V.

The image was developed under the above conditions, transferred to plain paper by corona discharge, and fixed under the same conditions as in Example 1. The image was extremely clear, free of blemishes, and of high density, and was superior to the image of Example 2 in terms of higher resolution and higher density. Subsequently, I obtained 50,000 sheets of recording paper, but I was able to obtain stable and unchanging images from the beginning to the end.

In addition, in the above embodiment, the results of changing the frequency and voltage of the AC voltage component applied to the sleeve 2 are shown in FIGS. 4 and 5. FIG. 4 shows the case of Example 1, and FIG. 5 shows the case of Example 2 and Example 3.

In Figures 4 and 5, the shaded area with horizontal lines is the area where fogging is likely to occur, the area shaded with vertical lines is the area where dielectric breakdown is likely to occur, and the area shaded with diagonal lines is the area where image quality deteriorates. The non-shaded range is the preferred range where stable and clear images can be obtained. As is clear from the figure, the range where fogging is likely to occur changes depending on changes in the AC voltage component. The waveform of the AC voltage component is
The waveform is not limited to a sine wave, but may be a rectangular wave or a triangular wave.

Furthermore, in FIGS. 4 and 5, the low frequency region shaded with scattered dots indicates the range where uneven development occurs due to low frequency.

In the above embodiments, if the toner in the two-component developer has magnetism, it goes without saying that the magnetic latent image can also be visualized under the same developing conditions.

〔Effect of the invention〕

According to the present invention, since the developer layer of the two-component developer is developed while being subjected to the action of an oscillating electric field within the development area, a toner for pressure fixing can be used as the toner, and therefore, Compared to conventional developing methods, the toner image can be easily fixed on the recording paper, and a recorded image with excellent clarity without fog can be obtained.

[Brief explanation of drawings]

FIGS. 1 to 3 are partial schematic sectional views showing examples of devices implementing the present invention, and FIGS. 4 and 5 respectively show cases in which the AC voltage component of the bias voltage is changed in the embodiment of the present invention. It is a graph showing the development state of. 1... Image carrier, 2... Sleeve, 3...
・Magnet, 4...Regulation blade, 5...
・Cleaning blade, 6... Developer reservoir, 7... Stirring screw,
8... Toner hopper, 9... Supply roller, 10
...Bias power supply, 11...Protection resistor, A...
-Development area, D...developer, T...toner particles, N, S...magnetic poles. Patent applicant: Konishiroku Photo Industry Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] (1) A method of forming a two-component developer layer consisting of toner particles and magnetic carrier particles on the surface of a developer transporting member, and developing an image on the surface of the image bearing member with the developer layer, comprising: A developing method, characterized in that toner particles for pressure fixing are used as toner particles, and the development is performed under an oscillating electric field. (2) The developing method according to claim 1, wherein the thickness of the developer layer is formed to be thinner than the gap between the image carrier surface and the developer transport carrier surface. (6) The developing method according to claim 1 or 2, wherein the toner particles are spherical toner particles. (4) The developing method according to any one of claims 1 to 3, wherein the oscillating electric field is formed between the developer transport carrier and the image carrier. (5) The developing method according to any one of claims 1 to 4, wherein the magnetic field is temporally varied in a region where the developer layer is vibrated by an oscillating electric field. (6) The developing method according to any one of claims 1 to 5, wherein the magnetic carrier particles are formed from a magnetic material and a resin.