JPH0285874A - Developing device - Google Patents

Abstract

PURPOSE:To omit bias application for recovering a toner and to enable a good image to be formed without causing staining of a background and scattering of a toner by setting a magnetic roll of a developer carrying sleeve in a moving state and forming a developing casing in contact with the top of a magnetic brush. CONSTITUTION:A carrier is erected like a brush by a magnetic force on the surface of the developing sleeve 4, and constantly circulated and conveyed from a toner supplying zone and a developing zone, and a developer is allowed to rotate like a spin motion by setting the magnet roll 5 of the sleeve 4 in a moving state in order to make it unnecessary to recover the toner after development. An amount of developer to be fed is regulated before and after the developing zone by forming the developing casing 3, and an air flow accompanied by conveyment of the developer is suppressed by arranging the casing 3 in contact with the top of the magnetic brush, thus permitting application of bias for toner recovery to be made unnecessary, developing conditions, such as development bias, to be stably maintained, and a good image to be formed without causing toner scattering and the like.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a developing device using a dry two-component developer, in which a carrier is periodically conveyed between a toner replenishing area and a developing area. The present invention relates to a developing device that replenishes toner and performs development.

[Prior Art] In general, in developing devices that use dry two-component developers that are installed in various image forming devices such as copying machines, various stirring mechanisms such as stirring rollers, conveyance screws, and stirring separators are used for large-scale developing devices. located inside the tank.

After the toner supplied into the developing tank from the toner hopper side is sufficiently stirred with the carrier by the various stirring mechanisms described above, it is replenished and supplied to the developing sleeve as a developer carrier, and the developer is deposited on the surface of the developing sleeve. The magnetic brush is made to stand up to form a magnetic brush. The height of the magnetic brush, ie, the amount of developer, is regulated to a constant state by the cutting action of the doctor blade.

- An electrostatic latent image corresponding to the image is formed on a latent image carrier such as a force photoreceptor, and when the ears of a magnetic brush are brought into contact with the electrostatic latent image in the development area, the electrostatic latent image is formed. Toner is supplied and developed to produce a visible image. When the developing operation is finished,
The developer constituting the magnetic brush is scraped into the developing tank, mixed and stirred again by the stirring mechanism such as the stirring roller, and is used for the next development cycle.

As described above, it is necessary to sufficiently stir and mix the dry two-component developer in order to maintain uniformity of toner concentration and to charge the toner well. Conventional developing apparatuses using a dry two-component developer have the advantage of being able to obtain stable image quality, but in order to achieve this, the developer must be sufficiently stirred and mixed. In order to perform sufficient stirring and mixing, various stirring mechanisms as described above are required, and space is also required to form a sufficient developer flow path, which increases the size and weight of the entire device. The problem is that it becomes digitized.

In order to solve these problems, a developing device has been proposed in which a two-component developer is used in a similar manner to a one-component developer, and the developing device is made smaller and lighter. In this miniaturized developing device, carriers that are constantly raised and attracted by a magnetic field emitted from a fixed magnet on the surface of a developing sleeve that is rotated and transferred in a fixed direction are brought into a toner replenishment area by the conveying action of the developing sleeve. The carrier is periodically conveyed to and from the developing area, and toner replenishing means and toner collecting means, which are integrated with rollers, are arranged so as to be in contact with the carrier in the toner replenishing area and the toner collecting area, respectively. . Then, toner charged by frictional action or the like is supplied to the carrier on the developing sleeve from the toner supplying means to form a magnetic brush. The developer spikes of this magnetic brush are conveyed from the toner replenishment area to the development area and come into contact with the electrostatic latent image, at which time the toner is subjected to a development operation.

There will be unevenness in toner density corresponding to the image in the developer of the magnetic brush sent to the area after development.
In the toner collection area, the toner in the magnetic brush is uniformly collected once by the toner collection means, thereby initializing the magnetic brush. Such toner recovery operation after development is performed by the action of a toner recovery bias voltage applied to the toner recovery means with a polarity opposite to the charged polarity of the toner.

[Problems to be Solved by the Invention] However, in a developing device that is made smaller and lighter by eliminating the stirring mechanism, it is important to perform the above-described toner recovery operation after development well. For this reason, if you increase the bias voltage for toner collection,
This bias voltage for collecting toner leaks through the carrier to the electrostatic latent image on the latent image carrier, which causes fluctuations in the developing bias, making image control difficult and causing background stains and toner scattering. The problem is that you end up doing it.

Therefore, the present invention uses a two-component developer in a similar manner to a one-component developer, in which the carrier that is constantly adsorbed in spikes on the developing sleeve is periodically conveyed between the toner replenishment area and the development area. In the developing device, which is designed to be smaller and lighter, it is possible to maintain stable developing conditions such as developing bias, and to form good images without background stains or toner scattering. The purpose of the present invention is to provide a developing device that has the following features.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a developer carrier including a magnet body arranged in a developing sleeve so as to be rotated in a fixed direction, A carrier is raised on the surface of the developing sleeve by a magnetic body and is periodically conveyed in cycles between a toner replenishment area and a development area, and a magnetic brush is used to replenish charged toner to the carrier in the toner replenishment area. a developing casing arranged so as to be in contact with the tip of the magnetic brush in a pre-development area and a post-development area between the toner replenishing area and the developing area. It has a structure.

[Function] In the means having such a configuration, charged toner is first fed from the toner replenishing means to the carrier which stands up on the developer carrying member and is being conveyed while being constantly held, and the toner is supplied with the developer. A magnetic brush is formed on the carrier, and the magnetic brush thus formed is fed into the development area. At this time, the developer ear of the magnetic brush performs a rotational spin motion on the developing sleeve by the rotational drive of the magnet body, and is moved and plucked while being stirred and charged, and the end of the developer ear of the magnetic brush It is conveyed while contacting the inner wall of the developing casing. This not only regulates the amount of developer, but also prevents toner from scattering by suppressing the air current generated as the developer spikes of the magnetic brush move within the developer casing.

On the other hand, the developer ears of the magnetic brush carried into the development area are
The electrostatic latent image formed on the surface of the latent image carrier is brought into contact with the electrostatic latent image to perform a developing operation. After the development is completed, the developer of the magnetic brush has toner density unevenness corresponding to the image, and in this state, it is about to be transported to the toner replenishment area again. However, the developer ears of the magnetic brush perform a rotational spin motion on the developing sleeve due to the rotational drive of the magnet, and are agitated by this, so the developer of the magnetic brush has a uniform toner concentration before being sent to the toner replenishment area. Then, a toner replenishment operation is performed.

Therefore, the amount of toner replenishment at this time is automatically set to the amount corresponding to the insufficient amount of toner with respect to the toner holding capacity of the carrier, that is, the amount of toner consumed. In addition, since the tip of the developer ear of the magnetic brush sent into the toner replenishment area is conveyed while contacting the inner wall of the developer casing, the airflow generated as the magnetic brush developer moves is suppressed within the developer casing. This prevents toner from scattering.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

As shown in the figure, a photoconductor 1 and a ram 1 as a latent image carrier have a condition of if<J! (not shown). It is rotationally driven in the direction of the arrow, that is, clockwise, by the l+ mechanism.

This photoreceptor drum is made of, for example, an organic photoreceptor (OPC), and is initially charged to a predetermined potential by a charging charger (not shown).

Furthermore, a developing device 2 is arranged close to the photosensitive tram 1 . Developing casing 3 of this developing device 2
A developing sleeve 4 made of a cylindrical member serving as a developer material carrier is provided inside, and a part of the developing sleeve 4 extends from an opening provided in the developing casing 3 to the photosensitive drum 1 side. It is exposed towards. ■The developing sleeve 1 is formed of a non-magnetic material such as aluminum oxide 11 into a hollow cylindrical shape, and is driven to rotate in the direction of the arrow, that is, counterclockwise, by a drive mechanism (not shown). At the same time, they are arranged so as to face the photoreceptor drum 1 with a certain gap therebetween.

A developing area is formed in a portion where the developing sleeve 4 and the photoreceptor drum 1 face each other.

On the other hand, inside the developing sleeve 4, there is provided a developing magnet roller 5 in which a plurality of different magnetic poles are alternately arranged. A magnetic brush B made of magnetic carrier and toner is made to stand on the outer surface of the developing sleeve 4 by the magnetic force generated from each magnetic pole of the developing magnet roller 5. The developing magnet roller 5 is rotationally driven in the direction of the arrow, that is, in the clockwise direction, by a driving mechanism (not shown), and the developer ears of the magnetic brush B are rotated by the rotation of the developing magnet roller 5 and the developing sleeve 4. is moved in the direction of the arrow, that is, counterclockwise, while performing rotational spin motion.

In this case, the carrier particles constituting the magnetic brush B are constantly raised in spikes without being peeled off from the developing sleeve 4 and are regularly conveyed in a cycle, and the toner particles are collected in a toner replenishment area to be described later with respect to this steady carrier. At the same time as the toner is replenished, the toner is consumed in the developing area. Further, a predetermined developing bias voltage is applied to the developing sleeve 4 from a power supply circuit (not shown). Note that the final developing bias value is determined depending on the original density or the user's preference.

Further, in an area opposite to the developing area, that is, in a rear area of the developing sleeve 4, a toner replenishing roller 6 as a toner replenishing means is installed so as to face the developing sleeve 4 with a predetermined gap, and this toner replenishing roller 6 is installed so as to face the developing sleeve 4 with a predetermined gap. One hener replenishment area is formed in the area where the replenishment roller 6 and the developing sleeve 4 face each other. Further, in a rear region of the toner supply roller 6, a toner tank 7 for storing new toner is integrally connected to the developer casing 3. The toner replenishing roller 6 is provided so that a part thereof is exposed at the outlet of the toner tank 7, and the exposed part toward the toner tank 7 is constantly in contact with the accumulated toner while rotating (not shown). It is rotationally driven in the direction of the arrow, that is, counterclockwise, by a drive mechanism. Then, the new toner stored in the toner tank 7 is replenished by the action of the toner replenishing roller 6 to the carrier which is constantly cycled as described above, and the magnetic brush B is formed. There is. An agitator 8 is disposed within the toner tank 7, and a toner cartridge 9 is detachably attached to the upper opening of the toner tank 7.

Further, one end edge of the toner layer regulating blade 10 is placed on the surface of the toner replenishing roller 6.
They are pressed together almost uniformly in the axial direction. On the other hand, the proximal edge portion of the toner layer regulating blade 10 is fixed to the outlet opening edge portion of the toner tank 7. The toner layer regulating blade 10 applies the toner particles on the toner replenishing roller 6 in an even thin layer, and also triboelectrically charges the toner particles.

Furthermore, a toner supply roller 11 is installed at the outlet opening of the toner tank 7 so as to bite into the surface of the toner supply roller 6 by a predetermined amount. The toner supply roller 11 is a member that causes the toner in the toner tank 7 to frictionally charge and evenly adhere to the toner supply roller 6. Further, the toner supply roller 11 is rotationally driven in the direction of the arrow, that is, in the clockwise direction, by a rotational drive mechanism (not shown).

In the rotational direction of the toner supply roller 6, the toner supply roller 11. A plate-shaped sealing member 12 is provided in pressure contact with the surface of the toner replenishing roller 6 in order to prevent the toner in the toner tank 7 from flowing out toward the developing casing 3. . This seal member 12 is made of Mylar.

Here, the developer casing 3 is formed in an arc shape in a developer transport area before and after the development @1 between the toner replenishment area and the development area, and the inner wall surface portion of the developer casing 3 formed in the arc shape is It is designed to come into contact with the tip of the magnetic brush B in the areas before and after development. Furthermore, an inlet seal plate 13 is attached to the edge portion of the developer casing 3 facing upstream of the development area to prevent toner from scattering from the opening of the developer casing 3.

In the apparatus in this embodiment, the toner in the toner tank 7 is first supplied to the toner supply roller 6 by the rotation of the toner supply roller 11 and held on the surface thereof.

The toner held on the toner supply roller 6 is triboelectrically charged while being uniformly made into a thin layer by the toner layer regulating blade 1o.

The charged toner on the toner replenishing roller 6 is fed to the carrier which stands up on the developing sleeve 4 and is being conveyed while being constantly held, thereby forming a magnetic brush B.

The magnetic brush B formed in this manner is conveyed toward the developing area, and at this time, the developer ears of the magnetic brush B undergo a rotational spin motion on the developing sleeve 4 by the rotational drive of the developing magnet roller 5. This allows stirring and
The above-mentioned magnetic brush B is moved while being charged.
The end of the developer ear is conveyed while being in contact with the inner wall of the developer casing 3, thereby regulating the developer. Therefore, in this embodiment, the conventional doctor blade is not required, and the rotational torque is reduced. Furthermore, the airflow generated as the developer ears of the magnetic brush B move is suppressed within the developer casing 3.

This prevents toner from scattering.

The developer spikes of the brush 6J and the air brush B that have been carried into the developing area come into contact with the electrostatic latent image formed on the surface of the photosensitive drum 1, and a developing operation is performed. After the development is completed, the developer of the magnetic brush B contains the image, ! ':
There is an unevenness of 1-4 degrees, and in this state it will be transported to the 1-ner replenishment area again. However, the developer spikes of the magnetic brush I3 are agitated by rotating on the developing sleeve 4 by rotation of the developing magnet roller 5. Due to the stirring action, the toner in the magnetic brush IA is made to have a uniform 1-toner concentration, and is then sent to the toner supply area. Therefore, the amount of toner replenishment by the toner replenishing means in the toner replenishment area is automatically set to the amount of shortage of toner with respect to the toner holding capacity of the carrier, that is, the amount corresponding to the consumption of toner. In addition, since the tip of the developer ear of the magnetic brush B that is sent into the toner replenishment area is conveyed while contacting the inner wall of the developer casing 3, the airflow generated as the magnetic brush B moves is transferred to the developer casing; 3 to prevent 1-ner scattering.

In the embodiment L, if the power supply circuit for applying the developing bias is configured to superimpose an alternating current on the direct voltage Aε, the developing efficiency can be increased and the image forming state can be further improved.

[Effects of the Invention] As described hereinafter, the present invention provides a 1- toner material that stands on the surface lx of the developing sleeve and is periodically conveyed in cycles between the 1-ner replenishment area and the development area. In order to avoid the need for the second collection operation, one magnet body in the first developer carrier is placed in a moving state to cause the developer to rotate on its own axis, and the developer can be developed in the areas before and after the development area. The developing casing is formed so as to be in contact with the tip of the magnetic brush so that the amount of FSL developer is regulated by the casing and the airflow accompanying the transport of the developer is suppressed. ! There is no need to apply a bias for recovering henna, image viewing conditions such as developing bias can be kept stable, and good images without background stains or toner scattering can be formed.

[Brief explanation of the drawing]

The figure represents a small-sized developer Mn for one embodiment of the present invention.
It is an explanatory longitudinal cross-sectional view of C. 1... Photosensitive drum, 2... Developing device, 3... Developing casing, 4... Developing sleeve, 5... Developing magnet roller, 6... Toner supply roller

Claims (1)

[Claims] A developer carrying member has a magnetic body inside the developing sleeve that is rotationally driven in a constant direction, and the magnetic body of the developer carrying body causes spikes of toner to stand on the surface of the developing sleeve and constantly move the toner between the replenishing area and the developing area. a toner replenishing means for replenishing the carrier with charged toner to form a magnetic brush in the toner replenishing area, and a developer transporting area before and after development between the toner replenishing area and the developing area. A developing device comprising: a developing casing arranged so as to be in contact with the tip of the magnetic brush.