JPH03139680A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To eliminate the need for an agitating device and other additional members by permitting carriers to form a screw for themselves by means of the magnetic force of a magnetism producing means. CONSTITUTION:A part of carriers is carried to a development zone through a gap between the doctor blade 4 and the sleeve 2, and the rest of them forms a stagnation part 41 on this side of the doctor blade 4. Naps are formed on this side of the stagnation part 41 by a magnetic pole 82. However, when the carriers are continuously sent to the stagnation part 41 by the rotation of the sleeve 2, a part of carriers forms a carrier-chain 42, is separated from the stagnation part 41, and constitutes a part of naps on this side of the stagnation part. Therefore, the bristle formed by the magnetic pole 82 becomes the screw 43 for the carriers, and rotates in the opposite direction (3) to the rotating direction (2) of the sleeve 2. Thus, carriers and toner, both of which compose a developer, can be continuously agitated without an extra agitating device.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic developing device such as a copying machine, printer, or facsimile, and more specifically to a developing device using a developer consisting of a carrier and toner. It is related to improvement.

[Conventional technology and problems]

Regarding electrophotography, a magnetic brush is formed and developed using a carrier such as iron powder and non-magnetic toner.
Conventionally, a two-component development method has been employed in which development is performed by applying a DC voltage between a photoreceptor and a non-magnetic sleeve serving as a developer transporting member. This method is the earliest established method, and involves mixing carrier and toner in a predetermined ratio, and using frictional charging to charge the toner to a predetermined polarity, the toner is attached to the electrostatic latent image area on the photoreceptor. , in addition to being easy to transfer,
This method is suitable for coloring, which has become popular in recent years, because it uses toner that does not contain magnetic bones. However, in order to satisfactorily charge the toner and carrier and maintain a uniform toner concentration in the consumed developer, a means for stirring the developer and a toner concentration monitoring device are required. However, it has the drawbacks of becoming larger and more complex, and increasing costs. These problems can be solved by using a resin carrier, commonly known as 1.
．． It is also incorporated in the five-component development method, and furthermore, in the one-component development method using magnetic toner, which is an alternative method to the two-component development method, toner aggregation that occurs when using insulating toner is avoided. In order to solve the problem of white spots in images caused by this, carriers have come to be used in combination, and in order to stabilize the image quality, it has become necessary to keep the toner concentration in the developer constant, resulting in similar problems.

[Means for solving problems]

An object of the present invention is to solve the problems of the prior art described above, and to provide a developing device using a developer consisting of a carrier and a toner.
This eliminates the need for a device to monitor the concentration of 1 henna in the developer and a stirring device to keep the toner concentration constant, and the purpose is to realize miniaturization and cost reduction of the device.

The present invention provides a magnetic ordering device having a movable part for attaching and conveying developer to a developing container TP disposed close to a photoreceptor for forming a latent image and a visible image to form a magnetic brush; A developing device is provided with a developer regulating plate that regulates the amount of developer conveyed before a magnetic brush forming area, wherein the developer is composed of carrier and toner, and the regulating plate and/or
Alternatively, an electrophotographic developing device characterized in that the carrier is configured to form a screw of the carrier by the magnetic force of the magnetism generating device before the developer regulating auxiliary plate provided upstream of the regulating plate. The content shall be as follows.

That is, the present invention provides an apparatus that solves the problems of using a carrier and toner as a developer in an electrophotographic development system, and can be effectively applied regardless of whether the toner used is non-magnetic or magnetic. It is.

The carrier that can be used in the present invention is fine particles of ferrite, iron, steel, or fine particles coated with resin or oxide film, and has an average particle size of 30 to 150 μm.
However, the performance as a magnetic material is more important than the particle size, and it is desirable that the saturation magnetization is 20 to 200 emu/g, and more preferably 50 to 200 emu/g, depending on the usage. It is desirable that it is ~200 emu/g. Further, when the toner used is a magnetic toner, it becomes bulky, and therefore, as a preferable condition during development, it is desirable that the saturation magnetization amount is approximately 10 emu/g or more larger than the saturation magnetization of the magnetic toner.

The toner that can be used in the present invention may be a non-magnetic toner whose main component is a styrene/acrylic copolymer resin or a polyester resin, and may also contain necessary pigments and others. It may be a magnetic toner that contains polyester resin as a main component, contains magnetic fine powder such as magnetite or ferrite, and also contains pigment, charge control agent, etc. In this case, the content of magnetic fine powder is 15 wt% or more. It is desirable that In any case, although the toner is not the main element of the present invention,
It is preferable that the insulation resistance is high in view of the conditions during development.

The gist of the present invention is that the carrier forms a screw in front of the developer regulating plate and/or the developer regulating auxiliary plate provided upstream of the regulating plate due to the magnetic force of the magnetism generating device, and the carrier forms a screw on the outside of the magnetic generating device. As the non-magnetic sleeve or hell 1-, which is a movable part for conveying the developer, rotates and moves, the screw rotates and works to take the toner near the screw into the carrier. .

It is preferable that the magnetic field distribution created by the magnetic generator to form the screw of the carrier is such that two magnetic poles of the same polarity are formed sandwiching the regulating plate and/or the regulating auxiliary plate. For example, Figure 1, ``2''
The magnetic field distribution and apparatus shown in the figure are inappropriate for the present invention.

That is, the type of two-peak magnetic pole shown in FIG. 1 is used to regulate the amount of developer produced by the magnetic poles (the part where the amount of developer is the coarsest), where θ-
20 to 32'', and θ4 (``θ3) -10 to 16°. Furthermore, Fig. 2 is described in Japanese Patent Application Laid-Open No. 59-231566, and as stated in the publication, by providing a magnet (18) on the downstream side of a magnetic particle restraining member (magnetic plate) (15), the magnet ( The magnetic flux density of the magnetic field formed by 14) is rapidly weakened, and the developer (non-magnetic) (17) is released without leaking the magnetic particles (16) in front of the magnetic plate F (15).
It is not suitable for forming a thin layer of water. In the figure, (1) is a photoreceptor, (12) is a sleeve, (13) is a developer container, (
19) is a bias power supply, and (20) is a sealing member.

As for the magnetic field distribution related to the present invention, for example, in the developing device having the configuration shown in FIG. 3, the one shown by the broken line in FIG. 4 is suitable. That is, due to the magnetic field distribution (8) created by the magnetic roll (3), which is a magnetism generator, magnetic poles (85) and (82) of the same polarity are created with the developer regulating plate (hereinafter referred to as a doctor blade) (4) in between. is formed.

Non-magnetic sleeve (2) which is a movable part that generally transports developer
When it rotates in the direction of the arrow (3), the magnetic force of the magnetic roll (3) causes the 4-wheel (7) held on the sleeve (2) to move in the direction of the broken line in FIG. At this time, part of the carrier is carried to the development zone through the gap between the doctor blade (4) and the sleeve (2), and the remaining part forms a retention part (41) in front of the doctor blade (4).

An ear is formed by the magnetic pole (82) in front of the retention part (41), but when the carriers are continuously fed into the retention part (41) by the rotation of the sleeve (2), some of the carriers become carriers. It becomes the center (42) and the retention part (41)
It separates from the area and forms part of the panicle in front of the retention section.

When this is repeated, the ears formed by the magnetic poles (82) become the carrier chains (42) supplied from the retention section (41).
), and the most upstream part is taken into the carrier layer (44).

Here, the ear formed by the magnetic pole (82) becomes the screw (43) of the carrier and rotates in the direction (arrow ■) opposite to the rotation direction (arrow ■) of the sleeve (2). Here, if there is toner (6) on the top as shown in Figure 3, the toner (6) will be taken into the carrier as the carrier moves, and the toner (6) will be mixed with the carrier (7) which is the developer. Stirring will occur continuously and without the need for special stirring equipment.

The magnetic field distribution of the present invention will be described in more detail as follows.

An angle θ1 formed between a magnetic pole (doctor pole) (85) on the downstream side across the doctor blade (4) and the doctor blade (4) is appropriately set between 5 and 35 degrees according to the conveying force by the doctor pole. Angle θ2 between the upstream magnetic pole (hereinafter referred to as stirring frame) (82) and the doctor blade (4)
is the carrier retention part (41) and the carrier screw (4).
3) cannot be secured, and it is necessary to sufficiently transport the carrier on the upstream side, so the angle needs to be 25 to 80 degrees.
5 to 60 degrees is suitable. There are also two magnetic poles (85), (
82) must be such that the carrier is held on the sleeve (2), and is preferably 50 Gauss or more, although it depends on the amount of saturation magnetization of the carrier. .

Furthermore, the shape of the magnetic field distribution (8) at the position of the doctor blade (4) is expressed by the amount of change in magnetic force, as shown in FIGS. 6 and 7, as an index that provides an appropriate conveying force to the developer. , ΔG/Δθ° is preferably 4 Gauss/1° or more, and if it is 2 Gauss/1° or less, the shortage of conveyance amount becomes noticeable.

To explain the magnetic field distribution in more detail, the developer container (5)
As shown in FIG. 4, the opening degree α of the developing tank (9).

When the magnetic poles (82) are distributed over the entire area of Angle α. When ゛ becomes wide, magnetic toner is transported by magnetic force, but non-magnetic toner is transported by dead particles.
Space is created, and the toner that was put in is not used and is wasted. Therefore, when using non-magnetic toner, the magnetic field distribution (8) changes as the polarity of the magnetic pole (82) changes (that is, the magnetic force
It is necessary to obtain a distribution such that the point (83) is located outside the developer container (5).

In the above explanation, the carrier screw is formed in front of the doctor blade (4), and the carrier and the ner are stirred. However, as shown in FIG. It goes without saying that the same effect can be obtained even if the developer regulating auxiliary plate (11) is provided and the carrier screw is formed in front of it. In this case, the gap between the auxiliary plate (11) and the sleeve (2) needs to be larger than the gap between the doctor blade (4) and the sleeve (2). In addition, the above description is based on the case where the movable part that conveys the developer is a non-magnetic sleeve.
It doesn't matter if it's the fastest belt-shaped body.

Now, regarding the amount of carrier used in the present invention, in the configuration shown in Fig. 3, the diameter of the non-magnetic sleeve is 20 mm, the axial length is 23 On+m, the opening angle is about 80°, and the doctor blade (
4) and the sleeve (2) is approximately 0°3 mm, and when using a ferrite carrier, it is preferable to weigh 35 g or more to form the carrier screw, although it depends on the position of the stirring pole (82), and the upper limit is This is until the carrier screw is buried in the carrier. If there is less carrier, the developer will be toner-rich, and conversely, if there is more carrier, the toner concentration of the developer will naturally be lower. For magnetic toner,
As it is itself controlled by a magnetic roll (3),
Good image quality can be obtained even when the toner is relatively rich, but in the case of non-magnetic toner, if the toner is too rich, it causes blurring, which is undesirable.In this sense, the developer concentration was lowered compared to the toner density in the case of magnetic toner. It can be said that better results can be obtained, and there is no problem if it is 10% or less, as is usually done.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the Examples.

Example 1 In the developing device configured as shown in FIG.
Move the PC photoreceptor 1 in the direction of the arrow ■ at a peripheral speed of approximately 47 mm/sec.
The non-magnetic sleeve (2) made of 5US316 and having a diameter of approximately 20 mm and an axial length of approximately 230+ nm is rotated by the arrow ■
The drum rotates at a circumferential speed of about 320 mm/sec in the direction of
After applying V and performing reversal development by rubbing with the tip of the developer, the image was transferred to paper and heat-fixed, resulting in a resolution of approximately 30.
Good printed matter with an image density of 0 to 400 dpl and an image density of about 1.38 was obtained.

The carrier used is ferrite whose main component is nickel-bent lead, and the average particle size is approximately 104 μm1 and the electrical resistance is approximately 2X.
It has a characteristic of 109 Ω-cm and a saturation magnetization of about 60 emu/g, and the amount used is about 10 g. The average particle size of the toner used was approximately 12μm, and the electrical resistance was approximately 4X1016Ω.
-cm, the main component is styrene/acrylic resin with a saturation magnetization of about 30 emu/g, and about 30-t of fine magnetite powder.
Negative charging (approximately -25μq/g) of a structure containing χ and other forces - bomb black, charged material, silica gel, etc. Magnetism 1 ~
It is na.

In this embodiment, the carrier was formed into a carrier screw having a diameter of about 15 to 20 mm by the mechanism described in detail above, and rotated in the opposite direction as the sleeve rotated to produce a toner stirring action. In addition, unlike when the carrier was alone,
When adding toner, the carrier screw has a diameter of approximately 10 to 1.
The diameter was reduced to 5 mm, but this is thought to be due to the fact that the average saturation magnetization amount of the developer became smaller due to the addition of toner, or that the frictional resistance was reduced by the toner.

The magnetic field distribution (8) due to the magnetic roll (3) is described according to the symbols in Figure 4: the doctor pole (85) is 660 Gauss, the stirring pole (82) is 615 Gauss, and the valley between the two poles (
84) is 390 Gauss, the amount of change in magnetic force ΔG/θ0 at the doctor blade (4) position is approximately 6 Gauss/1°, and the magnetic poles (85) and (82) are θ, respectively.
It was formed with a doctor blade sandwiched between -16° and θ2-34°. Doctor blade (4) and sleeve (2)
The gap was approximately 0.4 mm.

Example 2 With almost the same configuration as Example 1, -12 Yaria is made of magnetite and the surface is treated with violet. Average particle size is 77 μm, electrical resistance is approximately 1Xl06ΩcII+, saturation magnetization is 130 emu/g, and amount used is 150 g. Change it to
]・The average particle diameter of the toner is 12 μm, and the electrical resistance is approximately 1×1.
When we changed to a negatively charged non-magnetic toner mainly composed of 0+5 Ω-cm styrene/acrylic resin and performed reversal development, transfer, and heat fixing, good prints with a resolution of about 300 dpI and an image density of about 1.3 were obtained. Obtained.

(Effects of the Invention) As described above, according to the present invention, a carrier screw is formed, which eliminates the need for a stirring device and other incidental members that were required when conventionally using a carrier and toner. This contributes to miniaturization and lower cost.
The present invention is extremely useful.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional developing device and its magnetic field distribution, Fig. 2 is a schematic diagram of the developing device described in Japanese Patent Application Laid-Open No. 59-231566, and Fig. 3 is a schematic diagram showing an example of the developing device of the present invention. Figure 4 is a schematic diagram showing the magnetic field distribution of the device shown in Figure 3, Figure 5 is a conceptual diagram of the main part of Figure 3, and Figures 6 and 7 are the magnetic field distribution near the doctor blade, respectively. FIG. 8 is a schematic diagram showing another example of the developing device of the present invention. ■...Photoreceptor, 2...Sleeve 3...
Magnetic roll, 4...Doctor blade 5...
developer container, 6...toner 7...carrier,
8...Magnetic field distribution 9...Developer tank sweat-72 Go to Figure 5, Figure 6, Figure 1,! [Δ°′

Claims (1)

[Scope of Claims] 1. A magnetic device having a movable part for adhering and transporting developer to form a magnetic brush in a developing container disposed close to a photoreceptor for forming a latent image and a visible image. A developing device including a generator and a developer regulating plate that regulates the amount of developer conveyed before a magnetic brush forming area, wherein the developer consists of a carrier and a toner, and the regulating plate and/or An electrophotographic developing device characterized in that the carrier is configured to form a screw of the carrier by the magnetic force of the magnetism generator before a developer regulating auxiliary plate provided upstream of the regulating plate. 2. The developing device according to claim 1, wherein the carrier is appropriately selected from fine grains of ferrite, iron, and steel having a saturation magnetization of 20 to 200 emu/g, and fine grains coated with resin or oxide film. 3. Two magnetic poles of the same polarity are formed by the magnetic generation device with the developer regulation plate and/or the developer regulation auxiliary plate in between, and at least 50
It has a magnetic force of Gauss or more, and the angle between the upstream magnetic pole and the regulation plate and/or the regulation auxiliary plate is 25 to 60°, and the magnetic field distribution at the position of the regulation plate and/or the regulation auxiliary plate. Claim 1 wherein the slope is 4 Gauss/1° or more.
Or the developing device according to 2. 4. The developing device according to any one of claims 1 to 3, wherein the toner is a non-magnetic toner whose main component is a styrene/acrylic copolymer resin or a polyester resin. 5. The toner is a magnetic toner mainly composed of a styrene/acrylic copolymer resin or a polyester resin and a magnetic fine powder, and the content of the magnetic fine powder is 15 wt% or more. developing device.