JPH0229213B2 - GENZOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device that uses a dry developer to form a thin layer of developer on a developer holding member for development. The present invention further relates to a developing device that uses a non-magnetic developer to form a thin layer of developer on a developer holding member for development.

Prior Art Conventionally, various devices have been proposed and put into practical use as dry developing systems. However, in any of the developing methods, it is extremely difficult to form a thin layer of dry developer, and for this reason, the developing device has been constructed by forming a relatively thick layer. However, now that improvements in the clarity, resolution, etc. of developed images are required, it is essential to develop a method for forming a thin layer of dry developer and an apparatus therefor.

Japanese Patent Application Laid-Open No. 43037/1984 has proposed a method for forming a thin layer of a conventionally known dry developer.
And it has been put into practical use. However, this concerned the formation of a thin layer of magnetic developer. In order to make magnetic developers magnetic, it is necessary to add a magnetic substance to the developer. (Magnetic material is usually black)
There are problems such as poor color reproduction.

For this reason, methods for forming a thin layer of non-magnetic developer include a method in which soft bristles such as beaver hair are used as a cylindrical brush and the developer is adhered to the brush, and a method in which the surface is made of fibers such as velvet is used. A method has been proposed in which the developer is coated on the developing roller using a doctor blade or the like.

However, when an elastic blade is used as a doctor blade for the above-mentioned fiber brush, it is possible to regulate the amount of developer, but uniform application is not achieved, and the fibers of the brush are simply rubbed by the fiber brush on the developing roller. Since no triboelectric charge is imparted to the developer present in between, there is a problem in that ghosts and the like are likely to occur.

Purpose of the Invention In a separate application, the applicants have proposed a developer supply container and an opening of the container that faces the inside and outside of the container and faces the image carrier in the developing section. A non-magnetic rotating member for holding developer provided, a magnetic field generating means provided in this rotating member, and a blade member disposed opposite to the rotating member and allowing the developer to be conveyed to the developing section by the rotating member to pass therethrough. and forming a base layer containing magnetic particles on the rotating member in the container, further comprising a developer containing no magnetic particles on the base layer, or containing magnetic particles only in a smaller proportion than the base layer. An outer layer is formed, and developer is taken into the base layer from the outer layer by the movement of magnetic particles in the base layer as the rotating member rotates, and the developer taken into the base layer is passed through the blade section to the developing section. Although a conveying developing device has been proposed, the present invention is a developing device that forms a base layer and a developer layer simply and effectively, and stably forms a thin developer layer on the surface of a developer holding member over a long period of time. The goal is to provide equipment.

Structure of the Invention The apparatus according to the present invention includes a developer supply container, and a developer provided at the opening of the container so as to face the inside and outside of the container and to face an image carrier in a developing section. A non-magnetic rotating member for holding a developer, a magnetic field generating means provided in the rotating member, a blade member disposed opposite to the rotating member and allowing the developer to be conveyed to the developing section by the rotating member to pass therethrough, and the container. a base layer containing magnetic particles, which is formed and held in advance on the rotating member by the magnetic force of the magnetic field generating means, and a developing layer containing no magnetic particles or containing only a smaller proportion than the base layer. A storage part for storing the agent, and a partition member for releasably sealing a communication part between the storage part and the inner region of the container in which the base layer is formed, and the communication part by the partition member at the start of use. Since this is a developing device that forms an outer layer of the developer on the base layer by opening the seal of the passage and letting the developer fall from the storage section onto the base layer, the non-magnetic developer stored in the upper part By simply dropping the developer, two layers, a base layer and a developer layer, are reliably formed, and since the base layer has already been formed when the developer is dropped, the developer does not scatter. Does not occur.

Embodiments Examples of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram of an electrophotographic copying machine to which the developing device of the present invention can be applied, and shows a schematic cross-sectional view of a personal type copying machine main body. reciprocate in the direction. Reference numeral 2 denotes a short-focus, small-diameter imaging element array, and an original image placed on an original table is slit-exposed onto a photoreceptor 3. Although the photoreceptor 3 is shown as a photoreceptor drum, it may also be an endlessly moving web.
A charger 4 charges the photoreceptor 3 uniformly. The uniformly charged photoreceptor 3 is exposed to an image by an element array to form an electrostatic image. Next, the image is visualized by the developing device 5 according to the present invention. On the other hand, the transfer paper P is fed onto the photoconductor 3 by a paper feed roller 6 and a registration roller 7 that rotates at a timing such that it registers with the image on the photoconductor 3, and then is fed onto the photoconductor 3 by a transfer charger 8. The toner image on the photoreceptor 3 is transferred onto transfer paper. Thereafter, the transfer paper P is separated from the photoreceptor 3 and guided by a guide 9 to a fixing device 9, where the toner image on the transfer paper is fixed, and then discharged onto a tray by a paper discharge roller 11.
Here, the photoreceptor 3, the charger 4, the developing device 5, and the cleaning device 13 may be integrated into a process kit that is detachable from the main body, and maintenance may be simplified by integral replacement.

FIG. 2 is a sectional view of a developing device according to the present invention. In FIG. 2, the photoreceptor 3 moves in the direction of the arrow a. A non-magnetic holding member 22 that holds the developer is provided with a gap between the photoconductor 3 and, in this embodiment, the holding member 22 has a cylindrical shape, but it may also have a web shape that moves endlessly. . The same applies to the electrophotographic photoreceptor 3. Along with this movement of the photoreceptor 3, the developer holding member 22 is rotated in the direction of arrow b. A developer supply container 23 is provided to supply developer to the developer holding member 22. The developer supply container 23 has an opening near its lower part, and the developer holding member 22 is provided in the opening. Since a portion of the developer holding member is exposed to the outside through the opening, its surface moves from the inside of the developer supply container 23 to the outside, and then returns to the inside. Developer supply container 23
An enclosure is formed at the lower part of the developer holding member 22 so as to wrap around the lower part of the developer holding member 22 to prevent the developer from leaking to the outside. A fixed magnetic field generating means for generating a fixed magnetic field, that is, a magnet 24 is fixedly provided inside the developer holding member 22 . Therefore, only the developer holding member 22 rotates. This magnet 24 is N1, S1, N2, S2, N3, S3
has magnetic poles.

A magnetic blade (magnetic particle restraining member) 2 made of a magnetic material is installed near the upper part of the opening of the developer supply container 22.
5 is placed. There is a magnetic pole N1 of the magnet 24 on the opposite side of the magnetic blade 25 via the developer holding member 22, but the position of the magnetic pole N1 is upstream in the rotational direction of the developer holding member 22 from the position facing the magnetic blade 25. Angle θ (5 to 50
degrees) are placed out of alignment.

A magnetic particle base layer 32 containing magnetic particles is formed on the developer holding member 22 . This is composed of only magnetic particles or a mixture of magnetic particles and non-magnetic developer, but it is
Preferably, it contains 70% (by weight) of non-magnetic developer. The particle size of each magnetic particle is 30~200, preferably 70~
It is 150 microns. Each magnetic particle may be made of magnetic material alone or may be a combination of magnetic material and non-magnetic material. These particles form a base layer 32 on the holding member due to the action of the magnet 24. base layer 3
The magnetic particles in 2 form a magnetic brush by the magnetic field generated by the magnet 24, and this magnetic brush performs a circulating action as described below. A magnetic brush is also formed between the magnetic pole N1 and the magnetic blade 25, which restrains the magnetic particles of the base layer 32 within the developer supply container 23.

A partition plate 26 is provided on the upper part of the developer supply container 23, and this is adhered to the sheet guide 28 by heat sealing or the like to partition the upper and lower parts of the partition plate 26. A developer storage section 27 is formed above the partition plate 26. A non-magnetic developer 30 constituting a developer layer to be described later is stored above the partition plate 26, that is, in the developer storage section 27. This non-magnetic developer 30 is therefore stored without contacting and unmixed with the particles of the base layer 32. A small amount of magnetic particles may be added to the non-magnetic developer 30, but even in this case, the magnetic particle content is smaller than that of the magnetic particle storage section. Silica particles may be externally added to this non-magnetic developer to improve fluidity, and abrasive particles may be externally added to the non-magnetic developer for polishing the photoreceptor 3.

When using the developing device configured in this way, when the partition plate 26 is opened by pulling it out from the side (in a direction perpendicular to the paper surface of FIG. 2), the partition plate 26 The non-magnetic developer 30 stored above falls onto the top of the base layer 32. As a result, as shown in FIG. 3, two layers, the base layer 32 and the developer layer 33, are formed in the substantially vertical direction, and the developer device becomes ready for use. However, if an appropriate amount of non-magnetic developer is mixed with the magnetic particles 30 in the magnetic particle storage section, it can be used immediately as is, but if only magnetic particles are used, the non-magnetic developer is It is necessary to rotate the particles idly until they are mixed with the magnetic particles by the circulation action of a magnetic brush, which will be described later. When the non-magnetic developer 30 falls, the developer 30 does not pass through the gap between the developer supply container 23 and the developer holding member 22 and scatter. This is because the base layer 32 that has already been formed
This is because it fills this gap.

When the developer holding member 22 is rotated with two layers formed in this manner, the magnetic particles perform a circular motion as shown in FIG. 4 due to the magnetic field and gravity of each magnetic pole. That is, near the outer surface of the developer holding member 22, the magnetic particles in the lower part of the developer supply container 23 are moved along the outer periphery of the developer holding member 22 due to the interaction between the magnetic field from the magnet 24 and the rotation of the developer holding member 22. At this time, the non-magnetic developer and the surface of the developer holding member 22 come into contact with each other, and the non-magnetic developer in the base layer 32 is electrostatically applied onto the developer holding member 22.

In this embodiment, the non-magnetic developer is charged by friction with the magnetic particles or the developer holding member 22, but preferably there is an oxide film on the surface of the magnetic particles or at the same electrostatic level as the non-magnetic developer. If the developer holding member 22 receives the necessary charge by applying an insulating treatment such as a resin to reduce the triboelectric charge from the magnetic particles, it is possible to prevent the influence of deterioration of the magnetic particles and to prevent the developer holding member 22 from being affected by the deterioration of the magnetic particles. Stable developer application.

The magnetic particles rise as the developer holding member 22 rotates, but due to the magnetic field formed between the magnetic blade 25 and the magnetic pole N1, the developer holding member 22
It is prevented from passing through the gap between the surface and the tip of the magnetic blade 25. Therefore, the magnetic particles in this area are pushed by the magnetic particles that are sent one after another, rotate as shown in FIG. 4, and then fall slowly due to gravity. During this falling, the non-magnetic developer at the lower part of the developer layer 33 is taken in and returned to the lower part of the developer supply container 23, and this process is repeated.

On the other hand, since the triboelectrically charged developer is non-magnetic, it can pass through without being restrained by the magnetic field existing in the gap between the tip of the magnetic blade 25 and the surface of the developer holding member 22.
The magnetic brush portion formed on the magnetic blade portion applies a mirror force to the surface of the developer holding member and coats the surface of the developer holding member 22 uniformly and thinly, and then comes out of the developer supply container 23 and is exposed to light. It is subjected to development while facing the surface of the body 3.

The developing method used here is JP-A-55-
18656 is preferred. A voltage is applied between the electrophotographic photoreceptor 3 and the developer holding member 22 by a bias power supply 29 . Bias power supply 29
may be alternating current or direct current, but preferably one in which direct current is superimposed on alternating current. The developer provided by the development is supplied from the base layer 32 to the developer holding member 22, and the insufficient amount in the base layer 32 is supplied from the developer layer 33 by the aforementioned circulation movement. The base layer 32 is formed near the outer surface of the developer holding member 22 from the beginning of the operation of the developing device, and the developer layer 33 either does not contain any magnetic particles or contains magnetic particles that inevitably occur with the use of the device. Since the amount is small enough to compensate for the loss of particles, the condition of the magnetic brushes in the base layer 32 remains approximately constant and does not change over long periods of operation. In this sense, the magnetic particles in the base layer 32 are part of the development apparatus rather than the developer material or part thereof.

Further, it is preferable that the developer holding member 22 contacts only the base layer 32 and does not directly contact the developer layer 33. In this case, since the developer holding member 22 does not generate a conveying force for the developer layer 33,
Regardless of the amount of the developer layer 33, the developer content of the base layer 32 does not change.

It is desirable to consider the thickness of the base layer 32 in relation to the circular motion of the magnetic particles and the uptake of non-magnetic developer. That is, since the upper part of the base layer 32 functions to take in the non-magnetic developer,
Preferably, the upper portion moves as indicated by the arrow in FIG. This is because if the thickness of the base layer 32 is too large, the upper part of the base layer 32, that is, the contact portion with the lower part of the developer layer 33 will not move, making it impossible to take in sufficient nonmagnetic developer from the developer layer 33.

Based on the method described above, good results were obtained using a developer having the following configuration.

Base layer: Spherical magnetic particles of 80 to 150 microns, containing 35% (by weight) of non-magnetic developer with an average particle size of about 10 microns based on the magnetic particles.

Non-magnetic developer layer: Only the same developer as the non-magnetic developer in the base layer.

In addition, with the same configuration, a small amount (2
Good results were also obtained with the addition of ~5%) magnetic particles.

In order to subject the thus obtained non-magnetic developer coating layer to a developing action, the electrophotographic photoreceptor 3 having a dark area of -500V and a bright area of -250V as an electrostatic latent image is placed on the surface of the electrophotographic photoreceptor 3 and on a cylindrical developer holding member. 22 The cylindrical developer holding member 2 has an interval of 300 μm between the surfaces.
A voltage with a frequency of 1.6 KHz, a peak-to-peak value of 1.3 KV, and a center value of -250 V was applied between the photoreceptor 2 and the electrophotographic photoreceptor using a power supply E, and a good clear image without ghosts or fog was obtained using a Canon PC20 copier. It was done.

After about 2,000 copies were made, there was no change in image density until the non-magnetic developer layer was almost consumed, and no magnetic particles were used for development.

Although a magnetic blade is used in this embodiment, a non-magnetic blade may be used instead.

FIG. 5 shows another example of the partition plate 26 of the developer storage section 27. As shown in FIG. The end portion 36 of the partition plate 26 protrudes to the outside of the developer supply container 23, extends from there toward the interior of the container, and is inverted when it hits the inner wall of the container 23, forming a double configuration. The upper side of the double structure is adhered to the upper sheet guide 28 by heat sealing or the like. According to this configuration, by pulling the end portion 36, the partition plate 26
opens easily.

In any of the above embodiments, the developer 30 is stored in a fixed position in the developer supply container, but the developer storage section may be a replaceable cartridge.

Effects of the Invention As described above, according to the present invention, two layers (a base layer and a developer layer) can be reliably formed with a simple structure, and developer scattering does not occur during the formation. Furthermore, since the magnetic brush that takes in the developer and forms a thin layer on the developer holding member 22 is kept constant over a long period of time, a stable thin layer can be maintained for a long period of time. As a result, good development is achieved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an electrophotographic copy developing apparatus using the developing device of the present invention, FIG. 2 is a cross-sectional view of the developing device of the present invention, and FIG. 3 is a cross-sectional view showing the use state of the developing device of the present invention. , FIG. 4 is a sectional view showing the flow in the base layer, and FIG. 5 is a sectional view showing another embodiment of the partition plate of the developing device of the present invention. Explanation of symbols, 3: Electrophotographic photoreceptor, 22: Developer holding member, 23: Developer supply container, 24: Fixed magnetic field generating means, 25: Magnetic particle restraining member, 26:
Partition plate, 27: Developer storage section, 32: Base layer, 3
3: Developer layer.

Claims (1)

[Scope of Claims] 1. A developer supply container, and a developer holder provided at the opening of the container so as to face the inside and outside of the container and to face the image carrier in the developing section. a non-magnetic rotating member for use in the container; a magnetic field generating means provided in the rotating member; a blade member disposed opposite to the rotating member and allowing the developer to be conveyed to the developing section by the rotating member to pass therethrough; A base layer containing magnetic particles, which is formed and held in advance on the rotating member by the magnetic force of the magnetic field generating means, and a developer that does not contain magnetic particles or contains only a smaller proportion than the base layer. It has a storage section for storing data, and a partition member that releasably seals a communication section between the storage section and the inner region of the container in which the base layer is formed, and at the start of use, the communication path is closed by the partition member. A developing device for forming an outer layer of the developer on the base layer by opening a seal and allowing the developer to fall from the reservoir onto the base layer. 2. The developing device according to claim 1, wherein the developing device is replaceably mounted on an image forming apparatus. 3. The developing device according to claim 1 or 2, wherein an alternating current or direct current bias voltage is applied to the rotating member.