JPS60130770A - Developing device - Google Patents

Abstract

PURPOSE:To form a thin layer of a developer uniformly on a developer carrier and perform development stably without fogging nor edge effect by providing the magnetic layer to the developer carrier of a developing device which performs development in an oscillating electric field by using a two-component developer. CONSTITUTION:The layer of the two-component developer consisting of magnetic carrier particles and toner particles is formed on the surface of the developer carrier 2 and the oscillating electric field is established between an image forming body 1 and the deveoper carrier 2 by a bias power source 3, protection resistance 4, etc., to perform development. The developer carrier 2 is constituted by forming the magnetic layer 2b on a sleeve 2a formed of a nonmagnetic body such as stainless steel and Al. Consequently, magnetic force appearing on the surface of the developer carrier 2 is uniformed properly and the developer layer is therefore formed to relatively uniform thickness from the beginning of sticking.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrostatic latent image or a magnetic latent image formed on the surface of an image forming body by electrophotography, electrostatic recording, electrostatic printing, magnetic recording, or the like. Regarding a developing device of a recording device that attaches toner particles to an image, in particular, a layer of a two-component developer consisting of a mixture of magnetic carrier particles and toner particles is formed on the surface of a developer conveying carrier, and the developer layer is developed under an oscillating electric field. The present invention relates to an improvement in a developing device for attaching toner particles to a latent image on an image forming member.

[Prior art]

The above-mentioned developing device is disclosed in Japanese Patent Application Laid-Open Nos. 56-144452, 57-139761, and 57-147652.

This method is known from Japanese Patent Publications No. 58-48065.

By using a two-component developer, the developing devices described in these publications can easily control the triboelectrification of toner particles, compared to those using a single-component developer for magnetic toner particles. This makes it easier to form a developer layer uniformly on the surface of the developer transport carrier, and furthermore, the transfer of toner particles from the developer layer to the image forming body is easily controlled by the oscillating electric field. Therefore, in a method in which the developer layer is brought into contact with the image forming body by transferring toner particles from the developer layer to the image forming body under an oscillating electric field without bringing the developer layer into contact with the surface of the image forming body. This allows development to be carried out without scratches or fog, which are likely to occur. However, in such a developing device, in order for development to be carried out stably and to give a high-quality image with good reproducibility, the layer of the developer layer should not be brought into contact with the surface of the image forming member. It is important to form a thin and uniform thickness. If the developer layer is too thick or uneven,
It becomes difficult to stably control the movement of toner particles by the oscillating electric field, and fog and edge effects tend to appear, making it impossible to obtain the effects even if non-contact jumping development is carried out.

However, in the conventional developing device as described above, similar to the developing device that brings the developer layer into contact with the surface of the image forming body, the developer transport carrier is made of a non-magnetic material such as aluminum or stainless steel. V: In the developer layer formed on the surface of the developer transport carrier, variations in layer thickness tend to occur due to the magnetic pole arrangement of the magnet provided inside the developer transport carrier. There was a problem in that it was difficult to form a thin and uniform layer.

On the other hand, in a developing device in which the developer transport carrier rotates and the internal magnet remains stationary, and the developer layer formed on the surface of the developer transport carrier is brought into contact with the surface of the image forming member, the developer transport carrier is Japanese Patent Application Laid-Open No. 58-11 discloses a method in which a uniform magnetic layer is provided to cause variations in the magnetic field formed by the magnet body, thereby achieving high-concentration and high-contrast development.
This is known from Japanese Patent No. 5450.

[Purpose of the invention]

The present invention is capable of forming a thin and uniform developer layer on a developer transport carrier of a developing device that performs development under an oscillating electric field using a two-component developer, thereby stably performing development without fogging or edge effects. The purpose of this development is to provide a developing device that can develop a high-quality image with no streaks under non-contact jumping developing conditions. The present invention was achieved by discovering that a thin and uniform developer layer can be formed on a developer transport carrier by applying the technique described in Japanese Patent Application Laid-Open No. 115450/1983, which involves causing fluctuations in the magnetic field. It is something.

[Structure of the invention]

In the present invention, a layer of a two-component developer consisting of a mixture of magnetic carrier particles and toner particles is formed on the surface of a developer transporting carrier, and the toner particles are attached to the latent image of an image forming member from the developer layer under an oscillating electric field. In the developing device according to the present invention, the image portion transport carrier in step S1 has a magnetic layer.

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

FIG. 1 is a partial sectional view of a recording device showing an example of the developing device of the present invention, and FIGS. 2 and 3 are perspective views showing an example of the structure of a developer transport carrier, respectively.

W+y-? = 1△bu 11. -+Extrusion lr(!
tz 纺/7'l m9-%Il-1+ kr t84
It has an imaging layer consisting of a electrified body (not shown).

A drum-shaped image forming body 2 rotating in the direction of the arrow on which an electrostatic latent image is formed on the image forming layer by an exposure device or the like is a magnetic layer 2b on a sleeve 2a made of a non-magnetic material such as stainless steel or A1. The magnetic layer 2b has a magnetic layer 2b having a thickness of, for example, 50 μm as shown in FIG.
A magnetic metal material such as Ni is coated with a thickness of 50 to 2000 μm, as shown in Figure 3.
A layer formed of a layer sprayed by a metal spraying method so as to have a degree of 11Z, or a layer coated with a resin in which magnetic particles such as Ni or ferrite are dispersed are used. Note that the surface of the developer transport carrier 2 may be a smooth surface or a rough surface having appropriate irregularities. The rougher the surface, the higher the transportability of the developer layer formed on the surface. However, in the developer transport carrier 2 as shown in FIGS. 2 and 3, if a resin film is further provided on the magnetic layer 2b, the surface becomes insulating and the developer transport carrier 2 is subjected to a high bias. It becomes easier to apply voltage. In this respect, if the magnetic layer 2b is made of a resin layer containing dispersed magnetic particles, a relatively high bias voltage can be applied even without providing a resin coating on the surface.

3 is a bias power supply that applies a bias voltage to the developer transport carrier 2 via the protective resistor 4 and forms an oscillating electric field between the image forming body 1 whose base portion is grounded and the developer transport carrier 2;
is a magnet provided inside the sleeve 2a of the developer transport carrier 2, and the magnet 5 has a plurality of N and S magnetic poles arranged in the open direction on its surface, and the N and S magnetic poles are arranged in the open direction. Usually 500~
It is magnetized to a magnetic flux density of 1500 Gauss.

In the illustrated developing device, the magnet body 5 rotates in the direction of the arrow, and as a result, developer particles are attracted to the surface of the developer transport carrier 2 in the developer reservoir 6 in the form of magnetic carrier particles and toner particles. The developer layer is formed by moving in the direction of the arrow opposite to the rotation of the body 5, but even if the developer transport carrier 2 is stationary, it moves in the direction of movement of the developer layer. It may rotate in the same direction, it may rotate in the opposite direction, or the magnet body 5 may be stationary,
The developer layer may move with the rotation of the developer transport carrier 2. If the magnet body 5 is stationary, the magnet body 5
It is preferable that the magnetic flux density of the magnetic pole located on the surface portion facing the image forming body is larger than the magnetic flux density of the other magnetic poles. This may be done by increasing the magnetization or by placing magnetic poles close to each other.

In the developing device of the present invention, regardless of which method is used to form the developer layer, since the magnetic layer 2b as described above is provided on the developer transport carrier 2, the developer transport carrier 2 is provided with the magnetic layer 2b. The magnetic force appearing on the surface of the magnetic or non-magnetic layer 1 is suitably homogenized, so that the developer layer is formed with a relatively uniform thickness from the beginning of the deposition, and the magnetic or non-magnetic layer 1 is effectively controlled by the regulating blade 7. A uniform predetermined thickness is observed.

8 transfers the developer layer that has passed through the development area A to the developer transport carrier 2.
A cleaning blade 9 stirs the developer in the developer reservoir 6 to homogenize the mixture of toner particles and carrier particles, and also triboelectrically charges the toner particles. The agitation roller 10 is a toner supply roller that supplies toner particles from the toner hopper 11 to the developer reservoir 6.

In the developing device of the present invention, the developer layer that has been formed on the surface of the developer transport carrier 2 and the gap between the developer transport carrier 2 and the image forming member 1 does not come into contact with the surface of the image forming member 10. It is preferable to set a narrow gap.

As a result, development is performed without any scratches.

This gap is preferably several tens to 2000 μm. If this gap becomes too narrow, the developer layer must be formed thinly to accommodate it, and even if the developer layer is formed uniformly, uniformity of toner particles in the developer layer cannot be obtained. It may become impossible to sufficiently supply particles to the development area, making it difficult to perform stable and clear development. Also, the gap is 2000
If it greatly exceeds μm, it becomes difficult to control the transfer of toner particles using an oscillating electric field, making it impossible to obtain a sufficient developed density. However, when the gap is in the range of several tens to 2000 μm, toner particle transfer is effectively controlled by an oscillating electric field that does not allow the developer J'=5 to come into contact with the surface of the image forming body 1. , can be formed to a suitably uniform thickness, thereby making it possible to perform clear development without fogging or edge effects and, of course, without creating any scratches in the image.

In order to control the transfer of toner particles, the developer transport carrier 2
The electric field generated between the image forming member L and the image forming member L has an AC component effective value of 200 to 5000 V and a frequency of 100 Hz.
~10 kHz, preferably 30o~4000V
.

It is preferable that a bias voltage of 1 to 5 kHz is applied, thereby exhibiting an effective field strength of 300 to 5000 V/m+n. The bias voltage applied to the developer transport carrier 2 by the bias power supply 3 includes a DC voltage of an appropriate magnitude having the same polarity as the potential of the non-image area of the image forming member 1, in order to prevent fogging. Of course, it can be used as

In addition, the image forming body 1 and the developer transport carrier 2 are not limited to the illustrated example.
An oscillating electric field may be generated in the development area A by providing a wire electrode, a net electrode, or the like that does not impede the transfer of toner particles between the two, and applying a bias voltage thereto. In that case, a force obtained by superimposing a DC component on a bias voltage, a DC voltage applied to the developer transport carrier 2, or an oscillating voltage of a different frequency to the developer transport carrier 2 may be applied. be exposed. The waveform of the alternating current component of the bias voltage is not limited to a sine wave, but may be a triangular wave, a rectangular wave, or the like.

Further, by appropriately setting the voltage and polarity of the DC component of the bias voltage, the developing device of the present invention can be applied not only to positive development but also to reverse development. In the case of reversal development,
The DC component of the bias voltage is set to a voltage approximately equal to the potential accepted in the non-image background portion of the image forming member. Furthermore, the developing device of the present invention can also be applied to developing magnetic latent images by using toner particles containing a magnetic substance.

The developing device of the present invention is composed of a mixture of magnetic carrier particles with an average particle size of tens of micrometers to hundreds of micrometers and non-magnetic toner particles with an average particle size of tens of micrometers, similar to conventional two-component developers. A developer is also used, but in order to obtain high-quality images that reproduce delicate lines, dots, and differences in shading, it is necessary to use a developer with an N short average particle diameter of 1.
Toner particles of ~201zm and weight average particle size of 5~50μm
It is preferable to use a developer consisting of a mixture of magnetic carrier particles, and further, the magnetic carrier particles may be insulating particles such as particles whose surfaces are coated with a resin film or resin particles containing dispersed magnetic particles. This is preferable because a high bias voltage can be applied to the developer transport carrier 2.

The insulating properties of the carrier particles are preferably 10 8 Ωα or more, particularly 10 13 Ωσ or more in terms of resistivity. This resistivity is 1 Ky/cr on the packed particles after the particles are placed in a container with a cross-sectional area of 0°50 cm2 and tapped.
Apply a load of n2 and apply 100OV between the cart and the bottom electrode.
This value is obtained by reading the current value when applying a voltage that generates an electric field of /cm, and if this resistivity is low,
When a bias voltage is applied to the developer transport carrier, charge is injected into the carrier particles, making it easier for the carrier particles to adhere to the surface of the image carrier, or for bias voltage breakdown to occur more easily.

According to the developing device of the present invention, as described above, since the developer layer can be formed on the developer transport carrier 2 appropriately and uniformly without contacting the image forming body 1, It is easier to control the transfer of toner particles, so even if finely divided toner particles and carrier particles are used,
It is easy to separate only the toner particles from the developer layer and attach them to the electrostatic image of the image forming body, and as a result, a high quality image can be obtained.

Next, specific examples of the present invention will be shown.

(Example) In the developing device shown in FIG. 1, the thickness of the developer transport carrier 2 was formed by dipping it in a resin liquid containing fine iron powder on the surface of an Al sleeve 2a whose surface was roughened by sandblasting. It has a magnetic layer 2b of about 50 μm and has an outer diameter of 30 fins and rotates counterclockwise at 65 rpm,
The magnet body 5 inside the sleeve 2a has a magnetic flux density of 90 on the surface.
Has 8 N and S magnetic poles of 0 Gauss at equal intervals in the circumferential direction,
The rotation speed in the direction of the arrow was 700 rpm. The developer is made of insulating carrier particles with a weight average particle size of about 30 μm and a resistivity of about 1XIO”Ω, which contains magnetic powder dispersed in a resin, and insulating non-magnetic particles with a weight average particle size of 14 μm. Using a developer consisting of toner particles, the gap between the layer thickness regulating blade 7 and the developer transport carrier 2 was set to 400 μm, so that a developer layer with a layer thickness of about 500 μm was formed on the developer transport carrier 2. This developer transporting carrier 2 is moved in the direction of the arrow with an image forming layer made of an organic photoconductor 0PC.
Rotating at a surface speed of 20 vnn/sea, the imaging layer has a non-image background area of 411-1500 V for the 50 V.
The surface gap between the image forming member 1 on which an electrostatic latent image is formed and the surface is 700μ.
Development was carried out by applying a superimposed bias voltage of an AC voltage of 2 kHz, 1 kV and a DC voltage of 1150 mm to the developer transporting carrier 2 using a bias voltage 3 so that they faced each other.

The developed toner image was transferred by corona discharge onto plain paper by a transfer device H (not shown) and fixed by a heat roller fixing device with a surface temperature of 140°C.

The resulting recorded images are extremely clear, free from fog and edge effects, and have high density.
Subsequently, 50,000 sheets of recording paper were obtained in the same manner, and clear recorded images that remained stable from beginning to end were obtained.

On the other hand, if a developer transport carrier without a magnetic layer is used, the layer thickness regulating blade 70 is likely to be clogged with developer, and therefore the thickness of the developer layer will also be uneven. Adhesion of carrier particles to the toner image is also likely to occur;
The maximum number of sheets of recording paper that could be obtained was approximately 10,000 sheets, and roughness was observed in the recorded images.

〔Effect of the invention〕

According to the developing device of the present invention, it is possible to form a developer layer with an appropriate uniform thickness on the developer transport carrier, and therefore,
Transfer of toner particles from the developer layer is effectively controlled by the oscillating electric field, and clear recorded images without fogging or edge effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a recording device showing an example of the developing device of the present invention, and FIGS. 2 and 3 are perspective views showing an example of the structure of a developer transport carrier, respectively. DESCRIPTION OF SYMBOLS 1... Image forming body, 2... Developer transport phase body, 2a.
... Sleeve, 2b... Magnetic layer, 3... Bias power supply, 4... Hoki resistor, 5... Magnet, 6 - Developer reservoir, 7... Layer thickness regulating blade, 8... ... Cleaning blade, 9 ... Stirring roller, 10 ... Toner supply roller, 11 ... Toner hopper. Patent applicant: Konishiroku Photo Industry Co., Ltd., ``!'11 Agent: Patent attorney Haru Yasushi -7) Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] (1) A layer of a two-component developer consisting of a mixture of magnetic carrier particles and toner particles is formed on the surface of a developer transporting carrier, and a latent image of an image forming member is formed from the developer layer under an oscillating electric field. What is claimed is: 1. A developing device for adhering toner particles to a developer, wherein the developer transporting carrier has a magnetic layer. (2) The developing device according to claim 1, wherein the developer layer is formed on the surface of the developer transporting carrier so as not to come into contact with the surface of the image forming body. (5) The developing device according to claim 1 or 2, wherein the magnetic layer is a plated layer of magnetic material. (4) The developing device according to claim 1 or 2, wherein the magnetic layer is a layer containing magnetic particles. lζ1 6h @I 1st / Shikidai 11 Published 1
5. The developing device according to claims 1 to 4, wherein the screw is semi-insulating.