JP2657804B2 - Developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image formed on an image forming body with a two-component developer, and more particularly, to a developing device regulated under the influence of a magnetic force. A developing device that develops the electrostatic latent image with a thin developer layer.

[Background of the Invention]

2. Description of the Related Art Conventionally, for example, in electrophotography, electrostatic printing, electrostatic recording, and the like, as a device for developing an electrostatic latent image formed on an image forming body with a powder developer, a one-component developing device mainly including a magnetic toner is used. A developer or a two-component developer comprising a magnetic carrier and a non-magnetic toner by a developer carrier (hereinafter sometimes referred to as a sleeve) and a magnet roll disposed inside the developer carrier to form a developer flow; In order to make the developer flow a layer thickness suitable for development, for example, 0.5 to 5 mm thick, the developer flow is regulated by a developer layer thickness regulating member composed of a rigid plate-shaped member arranged close to the sleeve, and the obtained developer layer is covered with the latent image. A so-called contact development method in which development is performed by contacting an image surface is known.

However, in the above-mentioned contact developing method, since the developer layer is brought into direct contact with the entire surface of the latent image surface, that is, both the image portion and the non-image portion, the toner adheres to the non-image portion more or less to cause ground fog. However, there is a problem that the image becomes dirty and unclear.

Therefore, for example, Japanese Patent Application Laid-Open No. 55-18659 (A) discloses that a one-component developer flow conveyed on a sleeve is thinner than a gap between the latent image surface, for example, 500 μm or less, for example, 100 μm.
m or less, and an oscillating electric field is formed by applying an AC bias of a peak voltage of 800 to 1200 V at 1 KHz or less, for example, between the sleeve and the latent image surface. A method has been proposed in which a magnetic toner flies toward a latent image surface and is developed in a non-contact manner.

According to the non-contact developing method, the developer layer does not directly contact the latent image surface, and even if the toner flies and adheres to the non-image portion, the toner layer is pulled back to the sleeve side by the voltage in the opposite direction of the AC bias. And the occurrence of background fog is prevented, and a clear image can be obtained. However, in the non-contact developing method, the developer layer is, for example, 100 μm in order to achieve effective development.
m or less, and a conventional layer thickness regulating member such as a rigid plate-shaped member arranged close to the sleeve in the contact developing method cannot provide a desired developer layer at all. . That is, in the layer thickness regulating member of the plate-like body, the developer flow collides with the layer thickness regulating member and is rapidly dammed,
The turbulence causes the developer layer to become non-uniform, and immediately expands immediately after passing through the layer thickness regulating member to become a thicker and rougher developer layer than expected.

Further, the allowable range of the gap between the layer thickness regulating member and the sleeve is narrow, and there is an adverse effect that a slight change in the gap greatly affects the layer thickness of the developer layer.

For example, Japanese Patent Application Laid-Open No. 54-43038 (B) discloses that a one-component developer flow is regulated by a developer layer thickness regulating member composed of an elastic pressure contact plate disposed in pressure contact with a sleeve.
A technique for forming a 100 μm thin developer layer is described. Further, Japanese Patent Application Laid-Open No. 60-113274 (C) discloses a thin layer of a one-component developer by a developer layer thickness regulating member which is disposed in pressure contact with a sleeve and has an elastic pressure contact plate at least partially having a magnetic member. Is further disclosed in the publication, clogging due to foreign matters and the like mixed into the toner is avoided, and triboelectric charging of the one-component developer is sufficiently performed.
It is described that a uniform thin developer layer can be obtained.

Particularly, the technique using an elastic pressure contact plate having magnetism described in the latter publication (C) is considered as one effective means for forming a thin layer of the developer. The description of the specific configuration and conditions of use is poor, and it is necessary to repeat many more trials and errors in order to put it to practical use, leaving many questions as to whether it can be put to practical use.

Further, in the above publication, the target developer is limited to a one-component developer containing a magnetic toner as a main component, and the effect obtained when the one-component developer is used is described. It's just that.

By the way, the magnetic toner, which is the main component of the one-component developer, is composed of fine particles having an average particle diameter of 1 to 30 μm in which, for example, about 50% by weight of a magnetic substance is contained in a binder resin.
There is a problem with the main properties of the developer such as fluidity, triboelectricity and developability, and the magnetic attraction force to the developer by the magnet roll in the sleeve is insufficient, so that the transportability of the developer is reduced. However, there are also problems such as poor toner scattering.

FIG. 4 shows an example in which the formation of a thin layer is attempted by using an elastic pressing plate using a two-component developer, which has conventionally been difficult to form a thin layer because of containing a carrier having a relatively large particle size.

FIG. 4 is a sectional view of a developing device using the layer thickness regulating member. In the figure, 10 is an image forming body, 11 is a housing, 2 is a sleeve that rotates in the direction of the arrow, 1 is a magnet roll that has N and S8 poles, and rotates in the opposite direction to the sleeve 2, and 4 is an elastic pressing plate.
A layer thickness regulating member 4a and a magnetic material 4b, 5 is a fixing member for the member, 12 is a first stirring member, and 13 is a second stirring member. 14
And 15 are rotation axes of the stirring members 12 and 13, 16 is a replenishing toner container, 17 is a toner replenishing roller, 18 is a developer reservoir, 19 is a developing bias power source, 20 is a developing area, T is toner, and D is developer. Represents

In such a developing device, the developer D in the developer reservoir 18 is
Is sufficiently stirred and mixed by the first stirring member 12 rotating in the direction of the arrow and the second stirring member 13 rotating so as to overlap with each other in the opposite direction, and the sleeve 2 rotating in the direction of the arrow.
And the conveying force of the magnet roll 1 rotating in the opposite direction to the surface of the sleeve 2. A layer thickness regulating member 4 held by a support member 5 extending from the housing 11 is pressed against the surface of the sleeve 2 at a portion near a surface near the end portion, and regulates the layer thickness of the developer D being conveyed.
This developer layer develops the latent image on the image forming body 10 rotating in the direction of the arrow in the developing region 20 in a non-contact manner with a gap therebetween,
Form a toner image.

At the time of development (reversal development), a developing bias including a DC component and an AC component substantially equal to the potential of the non-exposed portion of the image forming body 10 is applied from the power supply 19 to the sleeve 2. Only toner is selectively transferred to and adhered to the surface of the latent image.

The thickness of the thin layer of the developer can be measured, for example, as follows. That is, the layer thickness is determined by comparing the positions of the projected image of the screen of the sleeve and the projected image of the state in which a thin layer is formed on the sleeve, using a Nikon Profile Projector of Nippon Kogaku Co., Ltd.

Next, one end of the layer thickness regulating member 4 is fixed by the supporting member 5, and the layer thickness regulating member 4 is elastically pressed against the sleeve 2 at a portion near the other end, and strongly regulates the developer flow by magnetic action. Through the gap with a layer thickness nearly equal to the average particle size, as a result, for example, 1000μm or less, preferably 30 to 500
μm thin developer layer. Thus, most of the foreign matter in the developer cannot pass through this gap and is automatically eliminated, thereby forming a uniform developer layer.

By the way, it is advantageous that the carrier and the toner constituting the developer layer have a small particle size from the viewpoint of the resolving power of image quality and the gradation reproducibility. For example, even when the carrier of the developer layer has a small particle size of 30 μm or less. By using a means such as the layer thickness regulating member 4, the uniform thin layer can be formed by automatically removing impurities, lumps, and the like in the developer. In addition, even when the carrier has a small particle size comparable to that of the toner, the mixing of impurities is similarly eliminated and a uniform thin layer can be formed.

Conversely, in order to prevent carrier adhesion of the image forming body 10,
A larger carrier particle size is preferable because it receives a strong magnetic force. For example, even with a carrier particle size of about 30 to 100 μm, a uniform thin layer of the developer can be formed by the above method. When the carrier particle size is large, the height of the carrier in the thin layer is large and the layer is coarse, and the developability is poor. From this point, it is desirable that the carrier particle diameter is 15 to 50 μm and the magnetization is, for example, 20 to 60 emu / g.

FIGS. 5A and 5B are a perspective view and a front view showing a specific structure of the stirring members 12 and 13 incorporated in the developing device. In the figure, 12a, 12b, 12c are stirring blades of the first stirring member, 13a, 13b, 13c are stirring blades of the second stirring member,
There are various aspects such as square plate blade, disk blade, elliptical plate blade,
Each is fixed to the rotation shafts 14 and 15 at different angles and / or positions. The two stirring members 12 and 13
Since the stirring blades are configured to overlap each other without colliding with each other, the stirring in the left-right direction is sufficiently performed, and the stirring in the front-rear direction is sufficiently performed due to the inclination of the stirring plate.

Further, the toner T supplied from the hopper 16 via the supply roller 17 is also uniformly mixed in the developer D in a short time.

The developer D sufficiently agitated and imparted with the desired triboelectric charge as described above is regulated by the layer thickness regulating member 4 in the process of being adhered and conveyed onto the sleeve 2 to form an extremely thin and uniform developer layer. Is done.

As described above, the developer layer thus obtained is extremely thin (10 to 500 μm), so that the gap between the image forming body 10 and the sleeve 2, that is, the developing gap is set to, for example,
By narrowing to 700 μm, non-contact development becomes sufficiently possible. Since the electric field in the developing region 20 increases when the developing gap is narrowed in this manner, sufficient development can be achieved even if the developing bias applied to the sleeve 2 is small, and there is an advantage that leak discharge of the developing bias is reduced. Further, the resolution and other image quality of the image obtained by development are generally improved.

The developing device having an extremely thin developer layer using the developer layer thickness regulating member described above has a remarkable effect in developing a small diameter sleeve, for example. That is, conventionally, for example, 30
When performing non-contact development using a small-diameter sleeve having a diameter of about 1 mm or less, a development gap of about 1 mm was necessary because it was difficult to regulate the thickness of the developer layer. For this reason, a high-voltage AC bias is required, and the resolution, gradation reproducibility, and overall image quality of an image obtained by development are reduced. In particular, details such as characters are not sufficiently reproduced, or the electrical insulation of the developing device is reduced. As a result, there were adverse effects such as difficulty in designing.

On the other hand, in a developing device using the developer layer thickness regulating member 4, an extremely thin developer layer is formed and developed, so that the developing gap can be reduced,
Since the electric field becomes sufficiently large, the resolving power, gradation reproducibility, and other image quality of an image to be developed are remarkably improved.
In addition, if a small-diameter sleeve is possible, an expensive developing device is reduced in size and cost is reduced. In addition, an image forming apparatus is easily arranged in a color electrophotographic device or the like that requires many developing devices, and the entire device is downsized. There are advantages.

Another advantage of the developing method using the developer layer thickness regulating member 4 is that scattering can be suppressed even when a carrier or toner having a small particle diameter is used.
That is, when the developing is performed using a developer including a carrier and a toner having a small particle size, the carrier and / or the toner may scatter and contaminate the inside of the apparatus, or a different color toner may be mixed in the developing apparatus containing the color toner. There was a problem that the color balance of the image was disturbed and fog occurred,
According to this developing device, since the developer layer is a thin layer, the spikes of the carrier are formed in a state where the magnetic binding force on the carrier is strong, so that the scattering of the carrier is prevented,
The scattering of the toner adhering to the carrier can also be prevented, and the above problems are completely solved.

Another effect is that the developing device is a non-contact developing device,
Since only the toner selectively flies toward the latent image surface and is developed, the toner on the latent image surface which tends to occur particularly when reversal development is performed using an image forming body having an organic photosensitive layer is considered. Fogging and carrier adhesion are prevented. Also, since the latent image surface is not slid, the surface of the image forming body is not damaged or a sweep is not formed, the resolution and gradation reproducibility are good, and a sufficient amount of toner is applied to the latent image surface. Can be attached. Further, since the image can be developed on the image forming body 10 on which the toner image is formed, it is suitable for multicolor development.

As a stable developing condition in a developing device using the developer layer thickness regulating member 4, it is preferable that the developer layer is 10 to 500 μm and the developing gap is 200 to 700 μm.

Next, the configuration of the developer toner applied to the development used for the developer layer thickness regulating member 4 is as follows.

Thermoplastic resin (binder) 80-90wt% Example: polystyrene, styrene acrylic polymer, polyester, polyvinyl butyral, epoxy resin, polyamide resin, polyethylene, ethylene vinyl acetate copolymer, etc., or a mixture of the above pigments (colorant) 0) 15% by weight Example: Black: carbon black, aniline black, furnex black, lamp black Yellow: benzidine derivative, auramine, tartrazine Magenta: rhodamine B lake, carmine 6B, Dupont oil red, rose bengal, hygment red, etc. : Copper phthalocyanine, sulfonamide derivative dye, aniline blue, methylene blue, etc. Charge control agent 0-5 wt% plus toner: Nigrosine electron donating dye, alkoxylated amine, alkylamide, chelate, pigment, 4
Negative toner: electron-accepting organic complex, chlorinated paraffin, chlorinated polyester, acid-excess polyester,
Chlorinated copper phthalocyanine, etc. Fluidizing agent Example: Colloidal silica, hydrophobic silica, silicon varnish, metal soap, nonionic surfactant, etc. Cleaning agent (prevents toner filming on photoreceptor) Example: fatty acid metal salt, Silicon oxide with organic groups on the surface,
Fillers (improve surface gloss of images, reduce raw material costs) Examples: Calcium carbonate, clay, talc, pigments, etc. In addition to these materials, to prevent fogging and toner scattering on the image surface, A small amount of magnetic powder may be contained.

As such magnetic powder, triiron tetroxide, γ-ferric oxide, chromium dioxide, nickel ferrite, iron alloy powder and the like having a particle size of 0.1 to 1 mm are used, and 0.1 to 5 wt% is contained. In order to maintain a clear color, the content is desirably 1 wt% or less.

Adhesive resins such as wax, polyolefins, ethylene-vinyl acetate copolymer, polyurethane, and rubber are used as the resin suitable for pressure fixing toner that is plastically deformed with a force of about 20 kg / cm and fixed to paper. Can be

Using the above materials, a toner can be produced by a conventionally known production method.

In the present developing device, in order to obtain a more preferable image, the toner particle size (weight average) is about 15 μm or less, particularly
It is desirable that the thickness be 9 μm. If it exceeds 9 μm, it is difficult to obtain sufficient resolving power and gradation reproducibility. If it exceeds 15 μm, it is difficult to obtain sufficient resolving power and reproducibility of gradation.
If it exceeds 15 μm, it becomes difficult to read fine characters, and if it is less than 1 μm, fogging occurs and the image becomes less clear. Here, the particle diameter or average particle diameter of the toner and carrier means a weight average particle diameter, and the weight average particle diameter is a value measured by a Coulter counter (manufactured by Tarta). The resistivity of the particles, after tapping putting the particles into a cylinder having a sectional area of 1.0 cm ^2, on packed particles 1 kg /
A thickness of about 1 mm is applied by applying a load of cm ² , and an electric field of about 10 ² to 10 ⁵ V / cm is generated between the load and the low surface electrode.

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

Carrier particles are those having magnetic particles and resin as main components, and are preferably spherical, and have a weight average particle size of 100 μm or less, particularly 15 μm or more and 50 μm or less, in order to improve resolution and gradation reproducibility. Those are preferred. Here, if the carrier particle diameter exceeds 50 μm, particularly 100 μm, the thickness of the developer layer is hindered, developability deteriorates, and image quality deteriorates. On the other hand, if the thickness is less than 15 μm, the developability of the developer, the triboelectric chargeability and the fluidity are poor, and carrier scattering occurs.

In addition, the resistivity of the carrier is set to 10 ⁸ Ωcm in order to prevent charges from being injected by the bias voltage to attach the carriers to the photoreceptor surface and to prevent the charges forming the latent image from disappearing.
Or more, preferably 10 ¹³ Ωcm or more, more preferably 10 ¹⁴ Ωcm or more.
An insulating material of Ωcm or more is preferable.

Such a carrier is produced by coating the surface of a magnetic substance with a resin, or by dispersing and containing magnetic substance fine particles in a resin, and selecting the obtained particles by a known particle size selecting means.

When the carrier is further made into a spherical shape, the following is performed.

Resin-coated carrier: Select spherical particles as magnetic particles. Magnetic powder-dispersed carrier: After forming the dispersed resin, spheroidizing treatment with hot air or hot water is performed, or a spherical dispersed resin is directly formed by a spray drying method.

When the carrier is made spherical, when passing through the gap between the developer carrying member and the elastic plate, the force received by the carrier is dispersed throughout the carrier, and the carrier is less broken, and the life of the carrier can be extended. it can.

It is preferable that the above-mentioned toner and carrier are mixed in such a ratio that the sum of the respective surface areas becomes equal. For example, when the average particle size of the toner is 10 μm and the average particle size of the carrier is 20 μm, the toner concentration (weight ratio of the toner to the developer)
Is suitably set to 5 to 40% by weight, preferably 8 to 25% by weight.

That is, in the developer applied to this example, unlike the conventional developer in which a large number of small-diameter toners on the outer periphery of the large-diameter carrier adhere, the carrier has a small particle diameter. It is considered preferable that the mixing ratio is such that the sum of the surface areas of the two becomes substantially equal.

Further, the developer applicable to this developing device is not limited to the two-component developer as described above. In addition to the magnetic carrier and the non-magnetic toner, for example, a toner in which a second non-magnetic toner having a different color is added is used. A component developer or a two-component developer in which a magnetic toner is added in addition to a magnetic carrier and a non-magnetic toner may be used. Similarly, a stable and uniform thin layer can be formed by adding various additives in addition to the carrier and the toner.

 Hereinafter, an example in which the above-described developing device is applied will be described.

(Reference Example) FIG. 6 is a sectional view of a main part of an image forming body, and the same reference numerals are given to the same contents as FIG. Reference numeral 20 denotes a non-contact developing device having the same configuration as that of FIG. 4, and the developer layer thickness regulating member 4 having the elastic pressing plate 4a and the magnetic body 4b of FIG. 1 is mounted. 21 is a corona charger, L is an image exposing light, 22 is a pre-transfer exposure lamp, 23 is a transfer pole, 24 is a separation electrode, P is transfer paper, and 25 is a static eliminator for cleaning with a static elimination electrode 25a and a static elimination lamp 25b.
Consisting of Reference numeral 26 denotes a cleaning device having a cleaning blade 26a and a bias roller 26b.

In this apparatus, image formation is performed as follows. After a charge is applied to the surface of the image forming body 10 by a corona charger 21 so as to have a uniform potential, an image exposure L is performed to form a latent image. This latent image is developed by the developing device 20 under the conditions described later to obtain a toner image. After the toner image is uniformly exposed by the pre-transfer exposure lamp 22, the toner image is transferred onto the transfer paper P conveyed at a predetermined timing by the action of the transfer pole 23, and the transfer paper P is imaged by the action of the separation pole 24. The toner image separated from the formed body 10 and further transferred by a fixing device (not shown) is fixed on the transfer paper P and discharged out of the apparatus. On the other hand, the surface of the image forming body 10 after the transfer is placed on the pre-cleaning charge removing device 25.
After being neutralized by the neutralizing electrode 25a and the neutralizing lamp 25b, the toner is cleaned by the blade 26a of the cleaning device 26, and the toner spilling out at this time is received by the bias roller 26b rotating by applying a bias, and is discharged by the discharging screw conveyor. Is done.

 Next, the used developer will be described.

 The toner is produced as follows.

100 parts by weight of polyester resin UX-K 120p (manufactured by Kao Soap Co.) 6 parts by weight of polypropylene 660p (manufactured by Sanyo Chemical Industries) 10 parts by weight of Mogar L carbon black (manufactured by Cabot) In a roll
After sufficiently kneading at a temperature of 140 ° C., the mixture is allowed to cool, and colorant particles having an average particle diameter of 10 μm are obtained by the steps of pulverization and classification by a coarse pulverizing jet mill. To 100 parts by weight of the colorant particles, 0.4 part by weight of hydrophobic fine silica R-812 (manufactured by Nippon Aerosil Co., Ltd.) is added and dispersed and mixed by a V-type mixer to obtain a toner.

The main physical properties of this toner are a resistivity of about 10 ¹⁴ Ωcm, an average particle diameter of 10 μm, and a specific gravity of 1.2 g / cm ³ .

 The carrier is manufactured as follows.

Spherical manganese-zinc ferrite particles (manufactured by TDK) are coated with a styrene-acrylic resin to a thickness of 1.5 μm on the surface of the particles using a spira coater to obtain a carrier. The main physical properties are that the average particle size is 30 μm and the resistivity is 10 ¹³
Ωcm, magnetization is 85 emu / cm ³ , and specific gravity is 4.6 g / cm ³ .

A desired developer is obtained by mixing 10 parts by weight of such a toner and 90 parts by weight of a carrier. If this is sufficiently stirred, the average charge amount of the toner will be about −20 μc / g.

 Table 1 summarizes the other image forming conditions.

[Problems to be Solved by the Invention] By the way, in the developing device as shown in FIGS. 4 and 6, it is possible to form a thin developer layer to some extent. It was difficult to form an agent layer. That is, since the layer thickness of the developer has been regulated by the pressing force of the elasticity of the layer thickness regulating member and the magnetism of the magnetic material, if the developer layer is to be made thinner than before, the pressing force increases. As a result, the load on the layer thickness regulating member increases, and the layer thickness regulating member and the sleeve surface may be adversely affected.

[Means for solving the problem]

(Object of the Invention) It is an object of the present invention to perform non-contact development on a thin developer layer of a two-component developer, and to provide high resolution and high density sharpness so that the layer thickness regulating member and the sleeve surface are not adversely affected. It is another object of the present invention to provide a developing device for forming a stable image.

(Constitution of the Invention) The object is to provide a developer container for storing a two-component developer composed of a toner and a magnetic carrier, a rotatable developer carrier disposed in the developer container, and the developer carrier. And a fixed magnet roll having a plurality of magnetic poles fixedly provided therein, wherein the two-component developer is used for non-contact development of the electrostatic latent image formed on the image forming body. An elastic pressure contact provided near the outer surface of the carrier, forming a wedge-shaped region between the carrier and the developer carrier, and having a tip facing the upstream side in the rotation direction of the developer carrier and having a magnetic material at least at the tip. A layer thickness regulating member that is a plate, an end of the magnetic material on the upstream side in the direction of rotation of the developer transport carrier is disposed between two magnetic poles having different polarities, and an upstream end of the magnetic material in the direction of rotation of the developer transport carrier. Side end and the developer transport than the end The thickness of the developer layer when developing the electrostatic latent image is regulated by the magnetic field generated between the magnetic pole on the upstream side in the carrier rotation direction and the amount of the developer conveyed to the wedge-shaped region by the rotation of the developer carrier. Is achieved by a developing device characterized in that

(Description of the Configuration of the Invention) The developer layer thickness regulating member used in the developing device of the present invention is constituted by an elastic pressure contact plate having a magnetic material at the tip, and a magnetic carrier between the elastic pressure contact plate and the sleeve. A thin developer layer is formed by allowing the developer to pass through a narrow gap close to the average particle size, thereby enabling non-contact development. When regulating the layer thickness of a two-component developer using an elastic pressure contact plate that presses only with mechanical pressure force, the tip of the elastic pressure contact plate that extends in the width direction is relatively large and is deformed by a hard carrier. As a result, the developer layer becomes uneven, and a uniform developer layer cannot be obtained.
Since the developer layer thickness regulating member of the present invention uses a magnetic action in addition to the mechanical pressure contact, the elastic pressure contact plate can be formed with a small amount of curvature and a reasonable pressure contact. Also, in the two-component developer, since the magnetic component in the developer is much larger than that in the one-component developer, influx of the developer more than necessary due to the magnetic action between the magnet roll and the elastic pressing plate provided with magnetism. There is also an effect that is prevented.

By the way, since the developer is transported to the developing area mainly by the rotation of the sleeve in that direction, the sleeve surface needs to have an appropriate and uniform rough surface. The roughness is preferably about 50 μm.

Next, as described above, in the present invention, the magnet roll in the sleeve is fixed, and in the present invention, for example,
As shown in FIG. 1, a magnetic material
4b, a horizontal magnetic field is formed between the magnetic body 4b and the magnetic pole N of the magnet roll 1 near the magnetic body 4b, and the developer flowing into the wedge-shaped space 6 formed between the elastic pressure contact plate 4a and the sleeve 2 is formed. The magnetic field is regulated by the magnetic field.

Further, as shown in FIG. 2 described later, a pressure contact point P to the sleeve 2 of the elastic pressure contact plate 4a and a magnetic body 4b straddling the tip of the elastic pressure contact plate 4a are provided on the pressure contact plate 4a, and a magnetic curtain at the pressure contact point P is provided. Alternatively, the developer layer may be regulated by both the horizontal magnetic field formed in the wedge-shaped gap 6.

In addition, the angle θ that allows for the range in which the horizontal magnetic field is formed
₁ (see FIG. 1) is preferably 0 ° <θ ₁ <60 °.

Further, the developer layer regulated by the layer thickness regulating member 4 according to the present invention develops an electrostatic latent image on the image forming body in a developing region with the magnetic pole of the fixed magnet roll facing the image forming body. However, in order to achieve more uniform thin layer development, the magnetic pole of the fixed magnet roll is shifted from the position facing the image forming body as described in, for example, JP-A-60-176069. Preferably, a horizontal magnetic field is formed and developed under the horizontal magnetic field.

As will be described later, an AC bias is applied to the sleeve 2. However, in order to achieve non-contact development with the two-component developer, a bias having a higher frequency and a higher peak voltage than that of the one-component developer is used. Is preferably applied.

2 and 3 show examples of the layer thickness regulating member according to the present invention, and the same reference numerals are given to the same contents as those in FIG. In the figure, reference numeral 3 denotes a fixed magnet roll 1 and a sleeve 2 rotating in the direction of the arrow.
The developing roll 4 is composed of an elastic pressing plate 4a and a magnetic material.
4b is a layer thickness regulating member, 5 is a support member of the layer thickness regulating member 4, 1 is the length from the press contact point P to the tip of the elastic pressing plate 4a on the sleeve 2 surface (tip play amount), h is A gap 6 between the distal end of the elastic pressure contact plate 4a and the sleeve 2 in the radial direction of the sleeve 2 indicates a wedge-shaped region formed between the distal end of the elastic pressure contact plate 4a and the sleeve 2 as described above.
The presence of the wedge-shaped region 6 has a close relationship with the amount of developer flowing between the elastic press-contact plate 4a and the sleeve 2 as described below.

That is, as shown in FIGS. 2 and 3, when a non-magnetic cylinder is used for the sleeve 2 and the flat elastic pressure contact plate 4a is pressed against the surface of the sleeve 2, the tip of the elastic pressure contact plate 4a and the pressed contact point P are pressed. A wedge-shaped space 6 is formed therebetween. When the sleeve 2 is moved in a predetermined direction in this state, the sleeve 2
The developer D held in the magnetic field by the magnet enters the wedge-shaped space 6 and the developer D sent to the surface of the elastic pressure contact plate 4a opposite to the sleeve 2 without entering the wedge-shaped space 6. Only the developer D that has entered the wedge-shaped space 6 is moved between the sleeve 2 and the elastic pressure contact plate 4a by the frictional force with the sleeve 2 and the pressure of the developer fed from the rear. Pass through to the development area.
At this time, when the amount of the developer that enters the wedge-shaped space 6 decreases, the amount of the developer that passes between the sleeve 2 and the elastic pressure contact plate 4a also decreases.

In the case of FIG. 2, as in the case of FIG. 1, since the magnetic body 4b extends to the tip of the elastic pressure contact plate 4a, a horizontal magnetic field is generated between the magnetic body 4b and the magnetic pole N of the magnet roll 1, and The flow of D into the wedge-shaped region is limited by the horizontal magnetic field.

Therefore, the flow of the developer D into the wedge-shaped region is restricted by the horizontal magnetic field, so that the amount of the developer passing through the space between the sleeve 2 and the elastic pressing plate 4a is reduced. The thickness of the layer can be reduced to a thin layer.

As the layer thickness regulating member 4, the elastic pressure contact plate 4a itself is made of a magnetic material, as shown in FIGS.
There is a magnetic material 4b bonded to 4a, a thin plate-shaped magnetic plate bonded to the entire front, back or both sides of the non-magnetic elastic plate 4a to form a sandwich.
It is sufficient that the magnetic material is provided at the leading end portion. Preferably, the magnetic material is provided in the vicinity of a position facing the magnetic pole of the magnet roll of the developing roll 3.

Examples of the non-magnetic elastic plate used for the layer thickness regulating member 4 of the various aspects include plastic, rubber, stainless steel, copper,
Brass, steel, phosphor bronze, etc. are used, and the magnetic material, the magnetic member such as a magnetic plate is a material which is strongly magnetized in the direction by a magnetic field, for example, metal such as iron, nickel, cobalt, ferrite, magnet, hematite, etc. Iron to start with,
Alloys or compounds containing ferromagnetic elements such as cobalt and nickel, or alloys that do not contain ferromagnetic materials but become ferromagnetic by appropriate heat treatment, such as manganese-copper-aluminum or manganese-copper- A Heusler alloy containing manganese such as tin and copper and chromium dioxide are used. As a representative example, the free length L is 5 as the elastic pressure contact plate 4a constituting the layer thickness regulating member 4 in FIG.
~ 20mm, thickness t is 0.05 ~ 0.2mm (0.1 ~ 2mm for rubber and plastic), tip play l is 1 ~ 3mm, pressing pressure 0.5 ~ 10gw (for 1mm width), elastic modulus 5000
225000 kgw / mm ² (however, in the case of rubber and plastic, the hardness is expressed by rubber hardness instead of elasticity coefficient and is preferably 20 よ い to 90 ゜ Hs).

Next, a configuration of a developing device for using the developer layer forming method will be described. Here, a non-magnetic cylindrical member is used as the sleeve 2, but a belt-shaped member or a planar member may be used. Depending on the shape of the sleeve 2, it is only necessary that a wedge-shaped space of a predetermined size be formed at the projected portion when the elastic pressure contact plate 4a is pressed. Further, the magnet roll 1 is built in the inside of the cylinder.
Is fixed. The magnet roll 1 fixed to the magnetic body 4b provided at the tip of the elastic pressure contact plate 4a
A horizontal magnetic field is formed between the magnetic field N and the magnetic pole N, and the flow of the developer D into the wedge-shaped region is limited by the horizontal magnetic field.

Further, a magnet piece 4b of the layer thickness regulating member 4 is arranged at a position facing the magnetic pole of the magnet roll 1 (however, when the elastic pressure contact plate 4a itself is made of a magnetic material, the above consideration is not necessary). A uniform developer layer may be formed by effectively applying magnetic attraction to the layer thickness regulating member 4.

Next, as development conditions, 500 Hz to 10 KHz and a peak voltage of 500 V
An AC bias of ~ 4 KV is applied. If the AC bias is less than 500 Hz, the toner flies insufficiently. If it exceeds 10 KHz, the toner flies cannot follow the frequency of the oscillating electric field, resulting in a decrease in density and carrier adhesion.
If the peak voltage is less than 500 V, the toner flies insufficiently, and if it exceeds 4 KV, carrier adhesion and ground fogging may occur.

In the case of normal development, a DC bias of 50 to 500 V and a polarity opposite to that of the toner is applied to the sleeve 2 so as to be superimposed on the AC bias to prevent background fog. Image forming body 10
When reversal development is performed using toner having the same polarity as the latent image charge, a DC bias having the same polarity as the toner and close to the surface potential of the image forming body 10 is applied.

(Examples) Hereinafter, the present invention will be described specifically with reference to examples, but embodiments of the present invention are not limited thereto.

FIG. 8 (a) is a cross-sectional view of a main part of a multicolor image forming apparatus for explaining the present embodiment, and FIG. 8 (b) is a cross-sectional view showing a writing device incorporated in the apparatus.

The multicolor image forming apparatus of FIG. 8A operates as follows. The image input unit IN includes an illumination light source 31, a mirror 32, and a lens 3.
3. The one-dimensional color CCD image sensor 34 is integrated into a unit, and the image input unit IN is moved in the direction of arrow X by a driving device (not shown), and the CCD image sensor 34 reads a document.

The image information read by the image input unit IN is transferred to the image processing unit
Converted to data suitable for recording by TR.

The laser optical system 36 forms a latent image on the image forming body 10 based on the image data as described below, and the latent image is developed to form a toner image on the image forming body 10. The surface of the image forming body 10 is uniformly charged by the scorotron band electrode 41. Subsequently, the image exposure light L according to the recording data is emitted from the laser optical system 36 onto the image forming body 10 via the lens. Thus, an electrostatic latent image is formed. This electrostatic latent image is developed by the developing device A containing yellow toner. The developing device A has the configuration shown in FIG. 4, but the magnet roll is fixed.

The image forming body 10 on which the toner image is formed is uniformly charged again by the scorotron band electrode, and receives the image exposure light L according to the recording data of another color component. The formed electrostatic latent image is developed by the developing device B containing magenta toner. As a result, a two-color toner image is formed on the image forming body 10 using the yellow toner and the magenta toner. Thereafter, similarly, cyan toner and black toner are superimposed and developed by the developing devices C and D, and a four-color toner image is formed on the image forming body 10. The developing devices B, C and D have the same structure as the device A. The multicolor toner image thus obtained is discharged by the exposure lamp 42 to facilitate transfer, and then transferred to the transfer pole 43.
Is transferred onto the recording paper P fed from the paper feeding device 48 in synchronism with the image formation. Recording paper P is separated pole 44
, And is fixed by the fixing unit 45. On the other hand, the image forming body 10 includes the removing electrode 46 and the cleaning device 47.
Is cleaned by

The cleaning device 47 has a cleaning blade 47a and a fur brush 47c. These are kept out of contact with the image forming body 10 during image formation, and when a multicolor image is formed on the image forming body 10, they come into contact with the image forming body 10 after transfer and scrape off transfer residual toner. . Then, cleaning blade 47a
Is separated from the image forming body 10 and is slightly fed, so that the fur brush 47c is separated from the image forming body 10. When the cleaning blade 47a separates from the image forming body 10, the fur brush 47c
It functions to remove the toner remaining on the top. 47b is blade 4
This is a roller for collecting the toner scraped in 7a.

The laser optics 36 is shown in FIG. In the figure, 37 is a semiconductor laser oscillator, 38 is a rotating polygon mirror, and 39 is an fθ lens.

The developer layer thickness regulating member 4 has the configuration shown in FIG. 7 and is incorporated in each of the developing devices A to D. In FIG. 7, 4c and 4e
Is a 0.1 mm-thick mylar film, and 4d is a 0.1 mm-thick steel magnetoelastic press-fitting plate, which are bonded to each other to form the layer thickness regulating member.

The carrier used here was the same as in the reference example.
The toner used was a black toner identical to that of the reference example, and the other toners used each colorant instead of carbon black. That is, auramine is used for the yellow toner, rhodamine B is used for the magenta toner, and copper phthalocyanine is used for the cyan toner. The mixing ratio between the toner and the carrier was 1: 9 (weight ratio). Table 2 shows other image forming conditions.

Under the above conditions, when a multicolor image was formed by developing in the order of yellow, magenta, cyan, and black, a high-density and clear color tone image without background fog was obtained.

(Embodiment 2) In this embodiment, instead of the developing devices (A, B, C, D) of the image forming apparatus of Embodiment 1, the magnetic poles in the developing section of the fixed magnet roll 1 face the image forming body 10. N, S
A developing device is used in which the middle of the magnetic pole is provided facing the surface of the image forming body (the surface closest to the sleeve 2).

According to the developing device of the present embodiment, the developing device is adjacent to the developing unit.
A horizontal magnetic field is formed between the N and S magnetic poles, and the electrostatic latent image on the image forming body 10 can be developed with a more uniform thin developer layer.

Example 1 except that the developing devices A, B, C, and D were as described above.
As a result, a clear, high-density color image was obtained even when 2,000 continuous copies were made.

〔The invention's effect〕

As is apparent from the above description, according to the developing device of the present invention, a magnetic body is provided at the tip of the elastic pressure plate, and a horizontal magnetic field is formed between the magnetic body and a magnetic pole of a magnet roll near the magnetic body. Since the developer flowing into the wedge-shaped space formed between the elastic pressure contact plate and the sleeve is regulated by the magnetic field, the amount of the developer passing through the space between the sleeve and the elastic pressure contact plate is also reduced, which means that Thus, the thickness of the developer layer in the developing region can be reduced. Therefore, a clear image having no background fog and a high density can be obtained. In particular, when applied to the formation of a multicolor image, a clear image having no color bleeding can be obtained.

[Brief description of the drawings]

1 and 2 are cross-sectional views illustrating the structure of the developer layer thickness regulating member of the present invention pressed against the sleeve surface, FIG. 3 is a partial cross-sectional view of the layer thickness regulating member of FIG. FIG. 5 is a sectional view showing an example of the developing device of the reference example. FIG. 5 (a) is a perspective view of a stirring device incorporated in the developing device of FIG. 4, and FIG. 5 (b).
FIG. 5A is a front view of the stirring device, FIG. 6 is a cross-sectional view of the image forming apparatus of the reference example, FIG. 7 is a cross-sectional view of the layer thickness regulating member of the first embodiment, and FIG. 8 is a cross-sectional view of the multicolor image forming apparatus according to the first embodiment, and FIG. 8B is a cross-sectional view of a writing device incorporated in the apparatus of FIG. 8A. DESCRIPTION OF SYMBOLS 1 ... Magnet roll, 2 ... Sleeve 3 ... Developing roll, 4 ... Layer thickness regulation member 4a ... Elastic pressure contact plate, 4b ... Magnetic material 5 ... Support member for elastic pressure contact plate 4a, 6 ... Wedge Shape area L: free length, D: developer P: pressure contact, d: gap between sleeve and layer thickness regulating member l: play amount, h: gap between sleeve and tip of layer thickness regulating member Gap 10: Image forming body (photoreceptor), 12, 13: Stirrer 16: Toner hopper, 17: Toner supply roller 18: Developer pool, 19: Bias power supply 21: Charger, 22 ... Exposure lamp before transfer 23 Transfer electrode 24 Separation electrode 25 Static eliminator before cleaning 26 Cleaning device 27, A, B, C, D Developing device IN Image input unit 34 …… CCD image sensor TR …… Image processing unit, 36 …… Writer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Kaneko 2970 Ishikawa-cho, Hachioji City Konishi Roku Photo Industry Co., Ltd.Judicial Chief Judge Kikuo Ozawa Judge Nobuyuki Shimizu Judge Osamu Komaki (56) References JP Akira 61-147264 (JP, A)

Claims (1)

(57) [Claims] 1. A developer container for storing a two-component developer comprising a toner and a magnetic carrier; a rotatable developer carrier disposed in the developer container; and a plurality of developer carriers inside the developer carrier. A fixed magnet roll provided with a fixed magnetic pole, and a non-contact developing device for the electrostatic latent image formed on the image forming body by the two-component developer, A layer which is provided in the vicinity of the surface, forms a wedge-shaped region between the developer carrier and the developer carrier, and has a tip directed toward the upstream side in the direction of rotation of the developer carrier, and at least the tip is a resilient pressure contact plate having a magnetic material at the tip A thickness regulating member, wherein an end of the magnetic body on the upstream side in the direction of rotation of the developer carrier is disposed between two magnetic poles having different polarities; and an end of the magnetic body on the upstream side in the direction of rotation of the developer carrier. And the direction of rotation of the developer transport carrier from the end. The amount of developer transported to the wedge-shaped region by the rotation of the developer transport carrier by the magnetic field generated between the upstream magnetic pole and the developer transport carrier is regulated, and the thickness of the developer layer when developing an electrostatic latent image is regulated. A developing device, characterized in that: