JPS60123859A - Developing method - Google Patents

Abstract

PURPOSE:To form a uniform toner layer which has a uniform polarity, large quantity of electrification and small thickness on a conveying carrier by adjusting the respective average grain sizes of a carrier and toner at specific grain sizes or below. CONSTITUTION:A two-component developer consisting of insulating carrier particles having 5-50mum average grain size and about >=10<8>OMEGAcm, more preferably >=10<13>OMEGAcm resistivity and toner particles having <=20mum average grain size is used. Ferromagnetic materials of metals such as iron, chromium, nickel cobalt, etc. or the compd. or alloy thereof or the ferromagnetic particles coated with various resins are used for the carrier particles. Various shapeless or spherical particles having <=20mum average grain sizes are used for the toner particles. A developer 9 is fed toward an arrow from a developer conveying carrier 5 and develops the electrostatic latent image on an image carrying body 1 on the surface of the carrier 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrostatic latent image formed on an image carrier by an electrophotographic method, an electrostatic recording method, an electrostatic printing method, a magnetic recording method, or the like. Regarding a developing method for attaching toner particles to a magnetic latent image, in particular, a two-component developer consisting of carrier particles and toner particles is supplied to the surface of a developer transport carrier to form a developer layer, and the developer layer is formed on the developer transport carrier. Toner particles are transferred from the developer layer on the surface to the toner transport carrier surface to form a single layer of toner,
The present invention relates to a developing method in which toner particles are caused to fly from a layer of toner on the surface of a toner transport carrier to the surface of an image carrier so that the toner particles adhere to a latent image on the image carrier. Incidentally, when the toner particles contain a magnetic substance, development of a magnetic latent image can also be applied.

[Prior art]

A developing method as described above is known from Japanese Patent Application Laid-Open No. 56-40862. In such a developing method, a two-component developer is used to first form a developer layer on the surface of a developer transporting carrier to control the charge polarity and charge amount of the toner particles. Incorporating the features of the development method using a two-component developer, which is said to be easy, the electrostatic latent image on the image carrier is developed by transporting toner particles from the developer layer of the developer transport carrier. By using a single layer of toner formed by transferring to the carrier surface, this method has the same characteristics as the development method using a -component developer, which essentially does not change the composition of the developer and does not easily cause deterioration of characteristics. In addition, the development is performed by a non-contact development method in which toner particles are selectively attracted to the electrostatic latent image and not displaced, and the development is performed by a non-contact development method that is generally required in such non-contact development methods. As mentioned above, two conditions were met: the toner particles must have uniform charge polarity and a considerably large amount of charge, and the thickness of the toner layer on the flying base should be fairly uniform and the surface condition should be uniform. This is achieved by using a component developer and by transferring toner particles from the developer layer of the developer transporting carrier to the surface of the toner transporting carrier to form a single layer of toner.

However, such a development method also uses a conventional two-component developer, that is, magnetic particles, carrier particles with a low resistivity and an average particle size of around 100 μm, and carrier particles with an average particle size of 2.0 μm.
When using a mixture of toner particles of around 0 μm, a single layer of toner can be formed on the surface of the toner transport carrier, as described in JP-A-56-40862. It is difficult to do this without using a method similar to the so-called magnetic brush development method in which the upper developer layer is brought into contact with the surface of the toner transport carrier. Since sufficient voltage cannot be applied to cause the transfer, it is difficult to obtain the desired toner layer on the toner transport carrier. In addition, in a method similar to the magnetic brush development method, especially when the particle size of the carrier particles is coarse, sweeping marks and uneven layer thickness are likely to occur in the formed toner layer. If a sufficient voltage cannot be applied between the toner particles, toner particles charged with opposite polarity due to friction between toner particles may be transferred to the toner transport carrier by the continuous image force. The conditions that the thickness of the toner layer on the toner transport carrier be thin and uniform and the surface condition be uniform, and that the toner particles have uniform charge polarity and a considerably large amount of charge are no longer satisfied, As a result, uneven adhesion of toner particles to the electrostatic latent image and so-called fogging in which toner particles adhere to areas other than the electrostatic latent image occur, making it impossible to develop a high-quality image.

[Purpose of the invention]

The present invention has been made in order to solve the problems of the above-mentioned developing method. To provide a method for performing non-contact development by forming a single layer of toner having a thin and uniform thickness and uniform surface condition, which is made of toner particles having uniform charging polarity and a considerably large amount of charge.

[Structure of the invention]

In the present invention, a two-component developer consisting of carrier particles and toner particles is supplied to the surface of a developer transporting carrier to form a developer layer, and the toner particles are removed from the developer layer on the surface of the developer transporting carrier. The toner is transferred to the toner transport carrier surface to form a single layer of toner,
In a method in which toner particles are caused to fly from a single layer of toner on a toner transport carrier surface to an image carrier surface to adhere to a latent image on an image carrier (the carrier particles have an average particle diameter of 5
The developing method is characterized in that the toner particles are made of insulating particles of 50 .mu.m or less, and the average particle diameter of the toner particles is 20 .mu.m or less, and this structure achieves the above object.

The method of the present invention is carried out using a developing device as shown in FIGS. 1 and 2.

In the figure, 1 is a rotating drum that has an image forming layer made of a photoreceptor or dielectric material such as SE on its surface, and an electrostatic latent image is formed on the image forming layer by a charging/exposure device (not shown). 2 is a roller-shaped toner transport carrier made of a non-magnetic material such as stainless steel or aluminum; 3 is a roller-shaped toner transport carrier that rotates in the direction of the arrow; 3 is a roller-shaped toner transport carrier that applies a bias voltage to the toner transport carrier via a protective resistor 4; The power to be applied, 5, is usually 500
~1500 Multiple magnetic poles N magnetized to the magnetic flux density of glass
, S is a cylindrical developer transport carrier made of a non-magnetic material such as stainless steel or aluminum, in which a magnet body 6 having magnets 6 and S is provided.
9 is a power supply for applying a bias voltage to a developer tank; 10 is a developer tank;
11 is a stirring blade that stirs the developer layer consisting of a mixture of carrier particles and toner particles in the developer tank 9; 11 is a layer thickness regulation blade that regulates the thickness of the developer layer on the developer transport carrier 6;
12 is a cleaning blade that scrapes off one layer of toner from the toner transport carrier 2; 13 is a cleaning blade that scrapes off the developer from the developer transport carrier 5; 14 is a toner hopper; and 15 is a toner particle T from the toner hopper = 14.
This is a toner supply roller that supplies toner to the developer tank 9. In the developing device shown in FIG. 1, the magnet body 6 rotates in the direction of the arrow, whereby a layer of developer in the developer tank 9 is formed on the surface of the developer transport carrier 5, and the magnet body 6 rotates in the direction of the arrow. The developer transport carrier 5 is preferably rotated in the same direction or in the opposite direction to the movement of the developer layer, but it may be stationary. . In the developing device shown in FIG. 2, the magnet body 6 is stationary and the developer transport carrier 5 rotates in the direction of the arrow, thereby forming a developer layer that moves with the rotation of the developer transport carrier 5. In the magnet body 6, the magnetic flux density of the magnetic pole facing the toner transport carrier 2 is made larger than the magnetic flux density of the other magnetic poles. This is done by, among other things, increasing the magnetization, and placing magnetic poles of the same or different polarities close to each other.

In the above-described developing device, the stirring blades 10 and the like stir the developer in the developer tank 9, and the toner particles become electrically charged mainly due to friction with the carrier particles and adhere to the developer transport carrier 5. The charged toner particles from the developer layer moving in the direction of the arrow are transferred to the toner transport carrier 2 by applying appropriate bias voltages to the developer transport carrier 5 and toner transport carrier 2 by power supplies 7 and 3, respectively. to form a single layer of toner on the toner transport carrier 2.
In the development area A where the 5 surfaces of the image carrier 1 face each other, toner particles from the toner layer of the toner transport carrier 2 fly and adhere to the electrostatic latent image on the image carrier 1. That is, the toner conveyance carrier 2 is provided so as to maintain an appropriately narrow surface gap with respect to the image carrier 1 so that a single layer of toner does not come into contact with it.

On the other hand, by carving the toner transport carrier 5, the toner transport carrier 2 can be used as an appropriate surface gap where the developer layer of the developer transport carrier 5 rubs, or an appropriate surface gap where the developer layer does not come in contact with the toner transport carrier 2. A narrow surface gap may also be used. However, in the present invention, in which insulating carrier particles having a resistivity of 10 8 Ωα or more are used as the developer, charged toner particles from the developer layer fly onto the developer transport carrier 5 and the toner transport carrier 2, and the toner is transported. Since it is possible to easily apply an appropriate bias voltage for transfer to the carrier 2, it is preferable to use conditions in which the developer layer does not come into contact without causing any risk of scratches or transfer of reversely charged toner particles.

The present invention provides a developing device having an average particle size of 5 to 50 mm.
A two-component developer is used which comprises insulating carrier particles having a resistivity in μm of 10 Ω or more, preferably 10 Ω or more, and toner particles having an average particle size of 20 μm or less.

The carrier particles used in the present invention include metals such as iron, chromium, nickel, and balt, or compounds and alloys thereof, such as triiron tetroxide, γ-ferric oxide, chromium dioxide, manganese oxide, ferrite, The surface of particles of ferromagnetic or paramagnetic material such as manganese-copper alloy is coated with styrene resin, vinyl resin, ethyl resin, rosin modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, etc. The resistivity can be obtained by coating with resin or fatty acid wax such as palmitic acid or stearic acid, or by making particles of the above-mentioned resin by dispersing fine particles of the above-mentioned magnetic material. is 1
08Ω or more, preferably 1013Ω or more, consisting of insulating magnetic grains with an average particle size of 5 to 50μm1, preferably 3
~30 μm. Note that, from the viewpoint of durability and stability, it is preferable to use a resin as the carrier particle rather than a fatty acid wax.

The resistivity of the carrier particles is determined by placing the particles in a container with a cross-sectional area of 0.5 cm2, tapping them, applying a load of KIKy/cm2 on the packed particles, and applying a load of 1000 V/cm between the load and the bottom electrode. This value is obtained by reading the voltage at which an electric field is generated and the current value when applied. Also,
The average particle size is the average of the long axis length and short axis length of each particle.

If the resistivity of the carrier particles is lower than 10 8 ΩG, problems arise in that the carrier particles tend to adhere to the toner transport carrier 2 or that a sufficient bias voltage cannot be applied.

Furthermore, when the average particle diameter of the carrier particles becomes smaller than 5 μm, the adsorption force by the magnetic force of the magnet body 6 becomes weaker, and on the other hand, the electric Ron force and Van der Waals force become stronger. Therefore, the carrier particles tend to adhere to the toner transport carrier 2 together with the toner particles. On the other hand, when the average particle size of the carrier particles becomes larger than 50 μm, the developer layer formed on the developer transport carrier 5 becomes rough, and the developer layer may rub against the surface of the toner transport member 20. Needless to say, even when toner particles are transferred without contact, a single layer of toner with a uniform surface condition cannot be formed on the toner conveying member 2. Furthermore, bias voltage breakdown and discharge tend to occur, making it impossible to apply high voltage to the developer transport carrier 5 and the toner transport carrier 2.

The toner particles used in the present invention are amorphous or spherical and have an average particle size of 20 μm or less, preferably 1 to 10 μm, like conventional non-magnetic or magnetic toner particles that are sorted by an average particle size sorting means. be. That is, using fine particles of resin or magnetic material as described for the carrier particles, adding a coloring component such as carbon and a charge control agent as necessary, and using a method similar to the conventional method for producing toner particles. can be made.

Note that the average particle diameter is the same value as defined for the carrier particles. .

When the average particle size of the toner particles is larger than 20 μm,
The amount of charge relative to the weight decreases, making transfer control difficult.
Resolution such as shading during development also decreases. Furthermore, if the average particle diameter becomes too small, the van der Waals force becomes large relative to the amount of charge due to friction of one toner particle becoming small, so the gap between the toner transport carrier 2 and the developer transport carrier 5 increases. Even if a bias voltage is applied to the toner particles, it becomes difficult to separate the toner particles from the carrier particles. Therefore, the average particle size of the toner particles is 0.5 to 20 μm, preferably 1 to 20 μm.
The range is preferably 10 μm. It is preferable to use a material that is triboelectrically charged so that the average charge amount is 3 to 300 μC/2, particularly 5 to 50 μC/2.

Furthermore, the toner particles preferably contain magnetic fine particles in an amount not exceeding 50 wt%. If the toner particles contain magnetic fine particles, they will be influenced by the magnetic force of the magnet 6 built into the developer transport carrier 5, so that the developer layer formed on the developer transport carrier 5 will be In addition to improving uniformity, toner charge controllability that selectively transfers toner particles with a large charge amount to the toner transport carrier 2 is improved, and as a result, toner particle controllability during development is also improved, reducing fogging. This prevents the occurrence of toner particles, and scattering of toner particles also becomes less likely to occur. However, if the content of magnetic particles is too large, the magnetic force of the magnet body 6 will be too strong, or the magnetic particles will appear on the surface of the toner particles, making it difficult to control triboelectric charging. The toner particles may easily aggregate with the carrier particles, making it difficult to transfer the toner particles to the toner transport carrier 2 and form a single layer of toner with a sufficient thickness. In the case of color toner, it may become difficult to obtain clear colors due to the color of the magnetic particles.

In the present invention, the carrier particles and toner particles as described above are mixed in the developer tank 9 in the same proportion as a conventional two-component developer. For this purpose, if necessary, a fluidizing agent is added to prevent the developer particles from flowing smoothly.
A cleaning agent and the like useful for cleaning the surfaces of the toner transport carrier 2 and the image carrier 1 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 surfactant such as fatty acid metal salt, organic group-substituted silicon, or fluorine can be used. I can do it.

By using the above-mentioned developer, the toner particles are sufficiently triboelectrified in the developer tank 9, and the carrier particles form a dense and uniform developer layer on the developer transport carrier 5 together with the toner particles. Since it is possible to apply a high bias voltage to the developer transport carrier 5 and the toner transport carrier 2 by forming a development process in which a single layer of toner can be formed with a large amount of charge, a uniform layer thickness, and a uniform surface condition, and toner particles are caused to fly from the toner layer and adhere to the electrostatic latent image on the image carrier 1. can be performed at high resolution without fogging.

In this case, the toner particles may be transferred from the developer transport carrier 5 to the toner transport carrier 2 under the condition that the developer layer is brought into contact with the toner transport carrier 2, but the transfer of toner particles charged to the opposite polarity is prevented. In order to achieve this, it is preferable to use conditions that do not allow the developer layer to come into contact with each other. That is, the gap between the toner transport carrier 2 and the developer transport carrier 5 is several tens to 2,000 μm.
m, and the layer thickness of the developer layer is regulated to be thick enough to not come into contact with the toner transport carrier 2 by the layer thickness regulating blade 11,
Power supplies 7 and 3 are connected between the toner transport carrier 2 and the developer transport carrier 5.
DC component of 50-100OV and 100Hz by
~10 kHz 1 preferably 1-5kHz 300-4
This is a condition in which a bias voltage consisting of an alternating current component of 000 V is applied, and as a result, toner particles are deposited on the toner transport carrier 2 to a thickness of several layers to form a single layer of toner.

If the gap between the toner transport carrier 2 and the developer transport carrier 5 becomes wider than 5000 μm, even if a bias voltage is applied between them, the effect will no longer appear, and toner particles will no longer be transferred. On the other hand, if the gap is made too narrow, the thickness of the developer layer to prevent contact will become too thin and uniformity will not be obtained, and therefore even a single layer of uniform and sufficient thickness will not be formed. In addition, it becomes easy to discharge between the toner transport carrier 2 and the developer transport carrier 5,
This can easily damage the developer or cause toner particles to scatter. In order to solve the problem of easy discharge, an insulating or semi-insulating surface layer of resin or oxide film may be provided on the surfaces of the developer transport carrier 5 and the toner transport carrier 2. Further, the DC component of the bias voltage between the toner transport carrier 2 and the developer transport carrier 5 is given with a polarity that promotes the transfer of charged toner particles to the toner transport carrier 2, and when the voltage value is increased, the toner Since the thickness of each layer becomes thicker and the image density becomes higher, this can be used for adjusting the image density. Note that when the toner particles are magnetic particles, this voltage value is increased.

The alternating current component of the bias voltage vibrates the developer layer, making it easier for toner particles to fly, and making it easier to form a uniform layer of toner on the toner transport carrier 2.
If the frequency is too small, the movement of the toner layer will be uneven due to the frequency, and if it is too large, the developer layer will not be able to follow it and the effect of vibration will be reduced. Although the voltage value of the AC component is also related to the frequency, the higher the voltage value, the more the developer layer is vibrated. However, if the charge is too high, toner particles with a small amount of charge also tend to transfer to the toner transport carrier 2, causing splatter.
Discharge becomes more likely to occur, and even carrier particles become more likely to transfer to the toner transport carrier 2.

The electrostatic latent image on the image forming body 1 is developed by flying toner particles from the toner layer on the toner conveying body 2 formed under the above conditions, on the surfaces of the toner conveying body 2 and the image forming body 1. The gap is several tens to 1000 μm, and the toner transport carrier 2
In order to prevent fogging, the electric potential of the non-image area of the image forming member 1 is higher than the potential of 50 to 500 cm by the L source 3.
DC voltage of 100 Hz to 10 kHz, preferably 1 to 5 kHz, in order to give vibration to the toner layer and even the flying toner particles to facilitate the transition of the toner particles to an electrostatic latent image. It is preferable to apply a bias voltage of 300 to 1000 V superimposed on an alternating voltage of 300 to 1000 V.

Here, if the surface gap between the image forming member 1 and the toner transport carrier 2 is too narrow, fogging is likely to occur, and bias voltage discharge is likely to occur, making the image forming member 1 more likely to be damaged. On the other hand, if the surface gap is made larger than 2000 μm, the effect of applying a bias voltage is no longer obtained, the transfer of toner particles is reduced, a sufficient developed density is not obtained, and the edge effect becomes noticeable. However, since the DC voltage of the bias voltage used to prevent fogging is to suppress the transfer of toner particles to the image forming member 1, it goes without saying that if it is too high, a sufficient developed density cannot be obtained.

When the toner particles are magnetic particles, this DC voltage can be lowered by providing a magnet inside the toner transport carrier 2 facing the development area A.

The alternating current voltage of the bias voltage is similar to the case of the transfer of toner particles from the developer transport carrier 5 to the toner transport carrier 2 as described above. If the voltage value is too high, fogging or discharge will occur. 1, and the toner particles are transferred from the developer layer of the developer transport carrier 5 to the toner transport carrier 2.
Since the purpose is to control the toner particles that migrate to the toner transport carrier 2, the bias voltage and pressure for transferring the toner particles from the developer layer to the toner transport carrier 2 are determined by the bias voltage applied to the toner transport carrier 2. This includes: On the other hand, between the image forming body 1 and the toner transport carrier 2,
This control '
If a bias voltage is applied to the magnetic pole to control the transfer of toner particles, this bias voltage will have almost no effect on the transfer of toner particles from the developer layer to the toner transport carrier 2. Toner transportation becomes possible.

Of course, the DC voltage of the bias voltage applied to the toner transport carrier 2 prevents fogging and promotes the transfer of toner particles from the developer layer to the toner transport carrier 2,
In addition, since the AC voltage ' also gives vibration and makes it easier for the toner particles to migrate, the voltage applied to the developer transport carrier 5 and the toner transport carrier 2 can sufficiently move the toner particles without providing a separate control electrode. Migration control can be performed.

The present invention also allows the image carrier to be
It can also be used for reversal development in which toner particles are attached to non-image areas of the image. In that case, a bias voltage having a DC voltage component substantially equal to the potential accepted in the non-image area of the image carrier 1 is applied to the toner transport carrier 2 .

Furthermore, the present invention can be applied to the development of magnetic latent images by using magnetic particles as toner particles.

〔Example〕

Hereinafter, the present invention will be further explained with reference to specific examples.

Example 1゜Carrier with average particle size of 30 μm1 magnetization of 50 emu,
/ ? The toner is made of resin-coated spherical ferrite particles with a resistivity of 1014 Ω or more, and the toner is made of styrene-acrylic resin (Sanyo Kasei Hymer UP).
110) Using non-magnetic particles obtained by a pulverization granulation method with an average particle size of 10 μm, consisting of 100 parts by weight, carbon black (110 parts by weight of Mitsubishi Kasei MA-100, and 5 parts by weight of nigrosine), Development was carried out using the apparatus shown in 1 under conditions such that the ratio of toner particles in the developer tank 9 to the carrier particles was 20 wt %.

The average charge amount of the toner was 15 μC/7.

In this case, the image carrier 1 is a CdS photoreceptor, and its peripheral speed is 1 s.
o trm/sea, the highest potential of the electrostatic image formed on the image carrier 1 -500■, the outer diameter 2 of the toner transport carrier 2
゜Rotation speed: 17 Orpm, 90.31111I between the image bearing member 1 and the toner transport carrier 2, that is, 300 p.
m % The outer diameter of the developer transport carrier 5 is 30, and its rotation speed is 10.
The magnetic flux density of the N and S magnetic poles of the 100 rpm magnet body 6 is 900 Gauss, and its rotation speed is 1'OOOrpm.The thickness of the developer layer on the developer transport carrier 5 is 0.6. M, the gap between the toner transport carrier 2 and the developer transport carrier 5 is 0.5 mm, the thickness of one layer of toner on the toner transport carrier 2 is 50 μm,) the bias voltage applied to the toner transport carrier 2 is a DC voltage of −250μ and an AC voltage. The frequency was 1.5 kHz, the superimposed voltage was 500 V, and the bias voltage applied to the developer transport carrier 5 was a DC voltage of +200 V. That is, in this case, the condition is such that the developer layer on the developer transport carrier 5 comes into contact with the surface of the toner transport carrier 2.

Development was performed under the above conditions, Senku was transferred onto plain paper using a corona discharge transfer device, and the resulting image was fixed through a hot roller fixing device with a surface temperature of 140°C. It was extremely clear with little effect or fog, 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.

On the other hand, when gelite particles with an average particle diameter of 30 μm and no resin coating are used as the carrier particles, the resistivity is 107 Ωcm (there is a bias voltage that can be applied to the toner transport carrier 2 and the developer transport carrier 5). The voltage values of the DC voltage and AC voltage became low, and the developed density also became low, and roughness was observed in the obtained image.

Example 2 As carrier particles, toner particles were made into toner particles using thermally spheronized magnetic particles with an average particle diameter of 20 μm, magnetization of 30 emu/f, resistivity of 1014 Ω or more, in which 50 wt% of fine ferrite was dispersed in a resin. Using non-magnetic particles with an average particle size of 5 μm, the developer tank 9 is
Development was carried out under conditions such that the ratio of toner particles in the developer was 10 wt % relative to the carrier particles. The average charge amount of the toner was 30 μalt.

In this case, the conditions of the image carrier 1 and the toner transport body 2 are the same as in Example 1, and the outer diameter of the developer transport carrier 5 is also 30 mm, but the rotation speed of the toner transport carrier 2 of the magnet body 6 is 150 rpm. The magnetic flux density of the magnetic pole facing the toner is 1200 Gauss, the thickness of the developer layer is 0.5111fi, the gap between the toner transport carrier 2 and the developer transport carrier 5 is 0.7 M, and the thickness of the toner layer on the toner transport carrier 2 is 40 μm1.Toner transport The bias voltage applied to the carrier 2 is a DC voltage of -200 V and a frequency of 2 kHz,
Superimposed voltage of 1000 V AC voltage, developer transport carrier 5
The bias voltage applied was a DC voltage of +400 cm. In this embodiment, the developer layer on the developer transport carrier 5 does not contact the toner transport carrier 2.

The image was developed under the above conditions, transferred to plain paper by corona discharge, and fixed through a heat roller fixing device with a surface temperature of 140°C. The resulting image on the recording paper had no edge effect. The image was clearer with no fog and higher density than the image in Example 1, and even though 50,000 sheets of recording paper were subsequently obtained, it was not possible to obtain an image that remained stable from beginning to end. Ta.

On the other hand, when carrier particles having a resistivity of 10<6 >[Omega] were used, the bias voltage that could be applied, such as DC voltage or AC voltage, became low, resulting in images with low density and roughness.

Example 3: 50 wt% of fine ferrite particles were dispersed in the resin as carrier particles, the average particle size was 20 μm, the magnetization was 30 emu/
f, using thermally spheroidized magnetic particles with a resistivity of 1014 Ωa or more, and toner particles with an average particle size of 5 μm.
Using the same non-magnetic particles as shown in FIG. 1, development was carried out using the same developing apparatus as shown in FIG. 1 under conditions such that the ratio of toner particles in the developer tank 9 was 10 wt % with respect to the carrier particles. The average charge amount of the toner was 30 μa/y.

In this case, the conditions of the image carrier 1 and the toner transport member 2 are the same as in Example 1, the outer diameter of the developer transport carrier 5 is also 30 cm, however, its rotation speed is 100 rpm, and the magnetic flux density of the N and S poles is 700 mm. Gauss, its rotation speed is 500 rpm.

The thickness of the developer layer is 0.6 fins, between the toner transport carrier 2 and the developer transport carrier 5 [Q, 7 m+++, the thickness of the toner layer on the toner transport carrier 2 is 30 μms, the bias voltage applied to the toner transport carrier 2 is -1oo DC voltage of v and 1kHz.

The superimposed voltage of 500v AC voltage and the bias voltage applied to the developer transport carrier 5 are +300v DC voltage and 3.5V.
The voltage was a superimposed voltage of AC voltage of 1500 V at kHz.

After developing under the above conditions, the image was transferred to plain paper by corona discharge and fixed by a heat roller fixing device with a surface temperature of 140°C. The image has no blemishes, is very clear with high density, and has higher resolution than the image in Example 1.
It was excellent in terms of high concentration. Subsequently, we obtained 50,000 sheets of recording paper, but were able to obtain stable and unchanging images from beginning to end.

On the other hand, when carrier particles having a resistivity of 10 5 Ω were used, the bias voltage that could be applied, such as DC voltage or AC voltage, became lower, resulting in a lower density image and roughness.

In the above embodiments, the waveform of the AC voltage component of the bias voltage applied to the toner transport carrier 2 and the developer transport carrier 5 is not limited to a sine wave, but may be a rectangular wave, a triangular wave, or the like.

Further, to adjust the image density, a method of changing the bias voltage applied to the toner transport carrier 2 and the developer transport carrier 5 can be easily used.

For example, to achieve high image density, (1) apply a high AC voltage to the toner transport carrier 2, (2) apply a low AC frequency to the toner transport carrier 2, and (3) apply a low DO voltage to the toner transport carrier 2. (4
) High DC voltage on developer transport carrier 5 (same polarity as toner)
(5) Apply a high AC voltage to the developer transport carrier 5 (
6) A low AC frequency may be applied to the developer transport carrier 5.

If the bias voltage is changed in the opposite way to the above, a low image density can be obtained.

This method of changing the bias voltage is related to positive development, but the same method can also be applied to reverse development or a method using a photoreceptor having an insulating layer on the surface. That is, the above (1), (2), (5), (6)
Regarding (4), an even higher DC voltage (same polarity as the toner) is applied so as to generate an electric field that facilitates the transfer of toner from the developer transport carrier 5.

In addition to the method described above, the image density can be increased by increasing the moving speed of the toner transport carrier 2 or the developer transport carrier 5.

In addition, when developing is not performed, the toner particles are not transferred to the toner transport carrier 2 by setting the toner transport carrier 2 in a floating state, stopping the application of the AC component, or setting the developer transport carrier 5 in a floating state. By using the seven methods of switching the DC component as described above, it is possible to easily prevent a single layer of toner from being formed on the toner transport carrier 2, or to prevent unnecessary development from being performed even if a single layer of toner is formed. can.

〔Effect of the invention〕

According to the invention, the insulating carrier has an average particle size of 50 μm or less, particularly preferably 30 μm or less, or an insulating carrier with an average particle size of 10 μm or less.
An excellent effect can be obtained in that a clear, fog-free recorded image 4 can be obtained without any trouble using the following toners.゛The present invention is based on Japanese Patent Application No. 58-183152 and No. 58-184381, in which colors are overlapped using dispersed color toner.
It can also be used for color development as described in the specifications of No. 58-187000 and No. 58-187001.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams each showing an example of a developing device used to carry out the developing method of the present invention. 1... Image carrier, 2... Toner transport carrier, 3.7
...Power source, 4,8...Protection resistor, 5...Developer transport carrier, 6...Magnet, 9...Developer tank, j
O-°' Stirring blade 11...Layer thickness regulating blade, 12, 13...Cleaning blade, 14...
Toner hopper, 15... Toner supply roller. Patent applicant Konishiroku Photo Industry Co., Ltd.

Claims (1)

[Scope of Claims] (1) A two-component developer consisting of carrier particles and toner particles is supplied to a developer transporting carrier surface to form a developer layer, and a developer layer is formed on the developer transporting carrier surface. In a method in which toner particles are transferred to a toner transport carrier surface to form a single layer of toner, and toner particles are caused to fly from the toner layer on the toner transport carrier surface to an image carrier surface to adhere to a latent image on the image carrier. , the carrier particles have an average particle size of 5 to 50
The average particle diameter of the toner particles is 2 μm.
A developing method characterized in that the particle size is 0 μm or less. (2) The developing method according to claim 1, wherein pressure is applied to form an oscillating electric field between the developer conveyance rejecting body and the toner conveyance carrier. (5) The developing method according to claim M1 or 2, wherein the toner particles are transferred from the developer transport carrier to the toner transport carrier by flying.