JPS59187370A - Developing device - Google Patents

Abstract

PURPOSE:To supply and apply an invariably specific amount of a developer onto a sleeve by positioning the 1st magnetic pole of a magnet near a specifying member and arranging the 2nd pole closely to a container side. CONSTITUTION:The 2nd magnetic pole of the magnet 7a is arranged closely to the container side, and then the magnetic field established by the 1st magnetic pole and the 2nd magnetic pole operates intensely upon the surface of the sleeve in the container to form a large magnetic brush in the container. Consequently, the draw-in amount of the developer to the magnetic brush becomes sufficient and large consumption of the developer is coped with sufficiently while magnetic particles are prevented from flowing out, so the protection of a surface to be developed and the prevention against the generation of a black part in a developed image are attained and operation for supplementing magnetic particles is unnecessary. The 2nd magnetic pole is arranged on the upstream side of the specifying member in the rotational direction of a specifying member holding member (sleeve) and in an area which has a starting line connecting the sectional center point of the holding member and the 1st magnetic pole together and is rotated by 180 deg. around the center point in the direction opposite to the rotational direction of the holding member.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device using dry-component developers.

Conventionally, various types of dry-component developing devices have been proposed and put into practical use. However, in any of the development methods, it is extremely difficult to form a thin layer of dry component developer, and for this reason, a developing device has been constructed by forming a relatively thick layer.

However, as improvements in the clarity and resolution of developed images are currently being sought, it is essential to develop a method for forming a thin layer of a dry component developer and an apparatus therefor.

A conventionally known method for forming a thin layer of a dry component developer is disclosed in Japanese Patent Application Laid-Open No. 43057/1983. Magnetic developers must have a magnetic material added to them in order to have magnetism, which causes poor fixing properties when heat fixing the developed image transferred to transfer paper, and adding magnetic material to the developer itself. There are problems such as poor color reproduction during color reproduction.

For this reason, methods for forming a thin layer of non-magnetic developer include a method in which a cylindrical brush made of soft hair such as beaver hair is used to adhere the developer to the brush, and a method in which the surface is coated with fibers such as velpet. A method of coating the developed roller with a doctor blade or the like has been proposed. However, when an elastic blade is used as a doctor blade in the fiber brush, 3J1. Although it is possible to control the amount of developer, it is not uniformly coated, and simply rubbing the fiber brush on the developing roller does not impart a triboelectric charge to the developer existing between the fibers of the brush. Therefore, there was a problem in that ghosts and the like were likely to occur.

The present invention eliminates the problems of the conventional method described above, and provides a new developing device that forms a uniform thin layer of developer on the surface of a developer holding member and applies sufficient triboelectric charging. The purpose is

The present invention proposes an innovative device for forming a thin layer of non-magnetic component developer.

A developing device of the present invention that achieves the above object includes a container for storing a non-magnetic developer and magnetic particles, a cylindrical developer holding member for rotationally conveying the non-magnetic developer to a latent image carrier, and the container. It is located on the side of the developer supply port and has a regulating member that regulates the amount of developer applied, and is located on the opposite side of the regulating member with a developer holding member in between, and has magnetic poles of opposite polarity at both ends. , a magnet forming a brush of magnetic particles on the holding member, one of the magnetic poles of the magnet is positioned as a first magnetic pole near the regulating member, and the other second magnetic pole is positioned in the rotation direction of the holding member. On the upstream side, the starting line is a line connecting the cross-sectional center point of this holding member to the first magnetic pole, and within an area rotated 180 degrees in the opposite direction to the rotational direction of the holding member around this center point. A second magnetic pole is provided at the position.

The latent image carrier of the present invention is a drum-shaped or belt-shaped member having a photoconductor or an insulating layer, and the magnet having the first and second magnetic poles is a plate-shaped or roller-shaped magnet. can be used. Furthermore, as the developer holding member, it is possible to use a sleeve made of non-magnetic metals such as aluminum, copper, stainless steel, brass, etc., or synthetic resin materials, and the sleeve is made of a synthetic resin material. Depending on the situation, a roughened surface or an uneven pattern may be provided.

Further, as the regulating member, a blade plate or a wall made of a magnetic material such as iron or a non-magnetic material such as aluminum, copper, or resin may be used.

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

FIG. 1 shows a sectional view of a developing device for explaining the developing principle of the developing device to which the present invention is applied.

In the figure, reference numeral 1 denotes an electrophotographic photosensitive drum, which holds a latent image formed by a latent image forming means (not shown), and rotates in the direction of arrow a to pass through a developing position shown in the drawing. A non-magnetic sleeve 2, which is a developer holding member for holding developer, faces the photosensitive drum 1 with a predetermined gap therebetween, and the sleeve 2 rotates in the direction of the arrow. A container 3 made of a non-magnetic material such as resin or aluminum is located above the sleeve 2 and stores a mixture of a non-magnetic developer 4 and magnetic particles 5, and downstream of this container 3 in the rotation direction of the sleeve. , a magnetic blade 6 is screwed.

On the other hand, a magnet 7 is provided on the opposite side of the sleeve 20 to the magnetic blade 6. The mounting position of this magnet is determined by the relationship between the position of the magnetic pole and the magnetic blade 6.
In fact, the effect of the magnetic field formed by the magnetic pole provided slightly upstream of the position of the magnetic blade 2 provides even better results in terms of preventing the magnetic particles from flowing out and uniformly applying the developer.

In the above configuration, the magnetic particles 5 in the container s are
The magnetic field generated between the poles and the magnetic blades 6 forms a magnetic brush 8. Then, as the sleeve 2 rotates, the magnetic particles and the non-magnetic developer are stirred and mixed while the magnetic plan 8 is held. In this state, on the magnetic blade side of the container 3, due to the presence of the blade 6, the mixture of developer and non-magnetic particles hits the magnetic blade, rises, and circulates in the direction of arrow C.

As a result, the p-nonmagnetic developer is triboelectrically charged by mixing with the magnetic particles. The charged developer is uniformly and thinly applied to the surface of the sleeve 2 by mirror force by a magnetic brush 8 formed near the magnetic grade B, and reaches a position facing the photoreceptor drum.

By the way, the magnetic particles 5 constituting the magnetic brush 8 are restrained by the magnetic field of the magnet 7, and the conveying force caused by the frictional force is less than the conveying force caused by the frictional force.
By setting it so that it forms a dog, it will not flow onto the sleeve 2. If there is non-magnetic developer within the area of the magnetic brush 8, the ratio of the magnetic particles of the magnetic brush 8 to this developer remains constant depending on the rotation of the sleeve 2.

As a result, even if the developer on the sleeve is consumed during development,
Developer is automatically supplied to the area of the magnetic brush 8. Therefore, it is possible to always supply and apply a constant amount of developer onto the sleeve 2.

In the above principle explanation, a magnetic blade is used as the regulating member, but a non-magnetic blade or a wall made of a non-magnetic material such as resin or aluminum constituting the container can also be used as the regulating member. However, in this case, in order to prevent the outflow of magnetic particles, it is necessary to further reduce the gap between the sleeve and the regulating member when using a magnetic blade.

Further, when a magnetic blade is used, it is preferable because a magnetic brush can be stably formed at the developer outlet by the magnetic field between the blade and the magnetic pole.

By the way, depending on the position of the second magnetic pole of the magnet 7a disposed in the sleeve 2 shown in the above-mentioned diagram M1, particularly on the side opposite to the magnetic blade 6, the state of the magnetic field appearing on the sleeve surface changes, and the development characteristics are greatly affected. Change. The following figures in FIGS. 2A and 2B are explanatory diagrams for explaining the development characteristics caused by the magnetic field on the sleeve surface depending on the placement position of the second magnetic pole. Although a magnetic blade is used as the regulating member in this example, the same effect can be obtained even when a non-magnetic blade is used.

First, FIG. 2A shows the state of the magnetic field generated when the second magnetic pole is disposed close to the downstream side of the magnetic blade 6 of the sleeve. On the other hand, FIG. 2B shows a case in which the second magnetic pole is arranged upstream of the magnetic grade, that is, closer to the container 3 side of the apparatus shown in FIG. 1. In the figure, the dashed lines indicate lines of magnetic force, and the magnetic particles in the container are strongly influenced by the lines of magnetic force and move on the sleeve and inside the container.

When the magnet 7a is arranged inside the sleeve as shown in FIG. 2A above, the magnetic field due to the first magnetic pole (S pole) is generated in a limited area on the side of the magnetic blade 6 and on the sleeve surface on the downstream side of this magnetic blade. .

For this reason, the magnetic brush on the sleeve that is formed by the magnetic field on the sleeve is strongly generated only in the vicinity of the magnetic blade 6, so there is a limit to the amount of non-magnetic developer that can be taken into this brush. . Therefore, when a latent image with a wide area or a latent image with a high potential is continuously developed, the amount of non-magnetic developer coated on the sleeve decreases, resulting in uneven development. Furthermore, since there is a magnetic field generated on the sleeve downstream of the magnetic blade 6 due to the relationship with the second magnetic pole, the magnetic particles forming a brush near this magnetic blade flow out from this blade. It becomes easier. The magnetic particles that reach the developing section in this manner damage the surface of the photosensitive drum 1 or cause black spots on the developed image, leading to a reduction in image quality.

On the other hand, by arranging the second magnetic pole (N pole) closer to the container as shown in Figure 2B, the magnetic field caused by the first magnetic pole (S pole) and the second magnetic pole is It acts strongly on the sleeve surface, allowing the formation of a large magnetic brush inside the container.

As a result, the amount of developer taken into the magnetic brush is sufficient, and development can be performed that can sufficiently follow up even with severe consumption of developer. Furthermore, in the case of FIG. 2B, the magnetic field generated by the relationship between the first and second magnetic poles on the downstream side of the magnetic blade is
Since the magnetic blade is extremely strong compared to the case shown in FIG. 2B, the outflow of the magnetic blade to the downstream side of the blade can be sufficiently prevented.

That is, in the case of FIG. 2B above, compared with the case of FIG. 2A,
It can sufficiently cope with severe consumption of developer and prevents the outflow of magnetic particles, so it not only protects the surface to be developed and prevents the appearance of black spots on the developed image, but also performs operations such as replenishing magnetic particles. is also no longer necessary.

In this way, when the magnet has a first magnetic pole at one end and a second magnetic pole having the opposite polarity to the first magnetic pole at the other end, the magnetic field generated by the relationship between the first magnetic pole and the second magnetic pole is By arranging the magnet at a position closer to the upstream side, it is possible to obtain good development results. In other words, the second magnetic pole is located upstream of the regulating member in the rotational direction of the regulating agent holding member (sleeve in the figure), and between the cross-sectional center point of the holding member and the first magnetic pole. The starting line is a line connecting the holding member, and the holding member may be rotated 180 degrees around this center point in the opposite direction to the rotating direction of the holding member.

Hereinafter, a more detailed explanation will be given based on examples.

〔Example〕

An embodiment of the present invention will be explained with reference to FIG.

In the figure, the same members as in FIG. 1 are given the same reference numerals.

In the embodiment device, the photoreceptor drum 1 is rotated 60 degrees in the direction of arrow a.
It rotates at a circumferential speed of 1/sec.

2 is a stainless steel (SUS 304) H with an outer diameter of 52 m and a thickness of 0.8 mm that rotates in the direction of the arrow.
Then, the surface was subjected to irregular sandblasting using Alundum abrasive grains of 600 mm, and the roughness of the circumferential surface was reduced to 0.8.
μm (R2=).

On the other hand, inside the sleeve 2 is a sintered ferrite type magnet 7.
b was fixed at the solid line position. At this time, the S pole of the first magnetic pole is
It was arranged at a position inclined by about 15 degrees (θ1 in the figure) with respect to the center point O from the line connecting the rotational center point of the sleeve 2 and the magnetic blade 6. The N pole of one of the second magnetic poles is located on a line rotated by 120 degrees (θ2 in the figure) in the opposite direction to the rotation direction of the sleeve 2, with the line connecting the center point 0 and the first magnetic pole as the starting line. Ta.

The S pole had a peak value of 800 Gauss on the sleeve surface in the presence of magnetic grade B, and 600 Gauss on the sleeve surface even when Grade 6 was removed. On the other hand, the magnetic flux density on the sleeve surface of the N pole, which is the second magnetic pole, was 600 Gauss.

The magnetic blade 6 is made of iron, and the surface thereof is plated with nickel to prevent rust. The distance between the blades 6 and the surface of the sleeve 2 was set to 250 μm.

The magnetic particles 5 have a particle size of 80 to 105 μm 1 maximum 6
100 spherical 7-elite (manufactured by TDK) of 3θmu/y
．． 9 was used. On the other hand, as non-magnetic developer 4, 3 parts of copper phthalocyanine pigment and 5 parts of negative charge control agent (alkyl salicylate metal chain) are used for 100 parts of polyester resin.
A negatively charged cyan powder with an average particle size of 12 μm was prepared in 2009.Then, the non-magnetic developer and magnetic particles were thoroughly mixed and placed in a container 3. Then, move the sleeve 2 in the direction of the arrow 60J12.
! When the sleeve 2 was rotated at a circumferential speed of 1/2, a developer layer with a thickness of approximately 120 μm was formed on the surface of the sleeve as the sleeve 2 rotated, and when the charged potential was measured by the blow-off method, it was found that - It was confirmed that it was charged uniformly at a potential of 7 μc/y.

On the surface of the photoreceptor drum 1 facing the sleeve 2, a charge pattern of +500 V in dark areas and +50 V in bright areas was formed as an electrostatic latent image, and the distance from the sleeve surface was set to 300 μm. Then, power supply E is applied to the sleeve at a frequency of 8.
When developing was carried out by applying a voltage of 0.00 Hz, peak-to-peak value of 1.8 KV, and center value of +200 ■, uneven development, ghost images, and black dot patterns due to outflow of turnips and magnetic grains were observed. I was able to obtain a high-quality image of the phenomenon. Furthermore, regarding the mixture in container 3, only the non-magnetic developer was consumed for development, with almost no magnetic particles being consumed. Furthermore, when the magnetic brush formed by the magnetic particles was observed in a state where most of the developer was consumed, it was confirmed that a sufficiently large magnetic brush was present.

Next, the magnet 7b in the sleeve is further rotated to the position indicated by the chain line, that is, the angle θ2, and the angle θ3 of the second magnetic pole is
It was placed at a position where the angle was 230 degrees. In this case, as a result of development under the same conditions as above, a black spot pattern was observed in the developed image, which was thought to be caused by outflow of magnetic particles. Furthermore,
When the state of the P air blank in the container 3 was observed at the stage when the developer was consumed, the shape of the brush was smaller than when the magnet 7b was placed at the solid line position.

Incidentally, in the present invention, the shape of the magnet is not limited to one having a rectangular cross section, but it is also effective to use a magnet 7C having a circular cross section as shown in FIG. 4, for example.

In addition, although the case where the S pole was used as the first magnetic pole on the regulating member side was illustrated in the above-mentioned specific example of the present invention, it is of course possible to use the N pole. Further, as for the regulating means, although a blade plate made of a magnetic material is illustrated, a wall or a plate-like member made of a non-magnetic material such as synthetic resin, aluminum, brass, stainless steel, etc. may also be used. However, when using a non-magnetic material, unlike when using a magnetic material, a magnetic field is not generated between it and the first magnetic pole, so the type of brush created by the magnetic particles inside the container is different. It becomes easier to leak from the downstream side of the container. However, this point can also be solved by setting the gap between the sleeve and the non-magnetic regulating means to be less than half the size of the magnetic particles. Furthermore, in addition to attaching the regulating member separately from the container, a part of the container may be used as a regulating plate. Incidentally, if there is a concern that the developer may leak out on the sleeve entrance side, a film material may be attached to the container as a leakage prevention member 9, as shown in FIG. However, in the present invention,
A magnetic brush generated by a second magnetic pole located on the side of the container can be used to replace this outflow prevention member. That is,
As shown in Fig. M4, a brush 10 with a second magnetic pole is strongly formed between the inner wall of the container on the entrance side of the sleeve, and this brush can effectively prevent the non-magnetic developer from flowing out. Further, the bias during development is not limited to an alternating voltage, but it is also effective to apply a direct current voltage.

For this purpose, it is possible to use a mixture of kneaded dyes and encapsulated products. As the magnetic particles, iron powder,
Ferrite or ferrite bound with resin can be used.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the parent plant device to which the present invention is applied, and Fig. 2A and Fig. 2B are explanatory views to explain the effects of the invention. FIG. 4 shows a sectional view of a copying apparatus showing an embodiment of the present invention. In the figure, 2...Sleeve 3 which is a developer holding member...Container 4...Non-magnetic developer 5...Magnetic particles 6...Magnetic plate which is a regulating member. 7... Show the magnet 4°

Claims (2)

[Claims] (1) a container for storing non-magnetic developer and magnetic particles; a cylindrical developer holding member for rotatably conveying the non-magnetic developer to the latent image carrier; A regulating member that regulates the amount of developer applied; and a regulating member that is disposed on the opposite side of the regulating member via a developer holding member and has magnetic poles of opposite polarity at both ends, and a magnetic particle formed on the holding member. a magnet forming a brush, one of the magnetic poles of the magnet is positioned as a first magnetic pole near the regulating member, and the other second magnetic pole is positioned upstream of the holding member in the rotational direction and on the side of the holding member. The center point of the cross section and the first
A developing device characterized in that a second magnetic pole is provided at a position within an area rotated 180 degrees in a direction opposite to the rotational direction of a holding member around this center point, with a line connecting the magnetic pole as a starting line. (2) The second magnetic pole is located on the inlet side of the developer holding member of the container and forms a magnetic brush made of magnetic particles to prevent the developer from flowing. The developing device according to item 1).