JPH0486778A - Carrier recovering device - Google Patents

Abstract

PURPOSE:To surely recover carrier whose grain size is small by providing a magnet in the inside of a brush roller where soft fibers having magnetism are planted on the outside circumferential surface thereof, rotating the brush roller in a reverse direction to the rotating direction of an image carrier and bringing it into contact with the surface of the image carrier. CONSTITUTION:The brush roller 21 obtained by planting a brush 23 constituted of the fibers to which the magnetism is given by scattering ferite in resin are planted on the outside circumferential surface of a roller 22 formed of an electrical conductive non-magnetic material is provided so as to be faced to the image carrier 2 at a position on the downstream side of the rotating direction of the image carrier 2 from a developing area. Simultaneously, the speed of the brush roller 21 is set to be almost identical to the circumferential speed of the carrier 2 and rotated in the reverse direction to the rotating direction of the carrier 2. Besides, the N1 pole of the magnet 24 provided on the inside circumference side of the brush roller 21 is faced to the carrier 2 and the S1 pole and S2 pole are placed at a position separated from the carrier 2 so as to make them adjacent. Thus, even the carrier whose grain size is small is surely recovered from the surface of the image carrier.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method for developing an image on the surface of an image bearing member using a developing device using a developer containing a mixture of toner and carrier. This invention relates to a carrier recovery device that recovers carriers that have adhered to the surface of an image carrier from the surface of the image carrier, and in particular can reliably recover carriers with small particle sizes that have adhered to the surface of the image carrier. This invention relates to a carrier recovery device.

[Prior art and its problems] Conventionally, developing devices used in image forming devices such as copiers and printers include developing devices using a one-component developing method that uses only toner as a developer, and There existed a developing device using a two-component developing method using toner and carrier.

Here, in a two-component development type developing device that uses toner and carrier as the developer, when development is performed on the surface of the image carrier, the carrier is supplied to the surface of the image carrier together with the toner. The carrier thus supplied may damage the surface of the image carrier, causing problems such as noise in the formed image.

Furthermore, in recent years, in order to perform highly accurate image formation in image forming apparatuses using the above-mentioned developing devices, consideration has been given to using carriers with small particle diameters.

In other words, using a carrier with a small particle size improves the contact efficiency between the carrier and the toner, accelerates the build-up of the toner charge amount, reduces the variation in the toner charge amount, and makes the toner extremely flexible and delicate. A magnetic brush is formed, allowing fine and delicate halftone development.

However, when a carrier with such a small particle size is used, the magnetic force in the carrier becomes weaker, so the carrier often detaches from the developing sleeve and adheres to the surface of the image carrier, and the line reproducibility becomes worse. When the developing bias voltage is increased in order to improve the image quality, a problem arises in that more carrier detaches from the developing sleeve and adheres to the surface of the image carrier.

On the other hand, in order to recover the carriers attached to the surface of the image carrier as described above, various studies have been carried out, for example, Japanese Patent Laid-Open Nos. 58-176661 and 60-86.
No. 583, Japanese Unexamined Patent Application Publication No. 61-200561, etc., disclose systems in which carriers attached to an image carrier are recovered by the action of magnetic force or electric field.

However, since the methods disclosed in these publications collect carriers attached to the surface of the image carrier in a non-contact manner, small-sized carriers such as those mentioned above may not adhere to the surface of the image carrier. In this case, there is a problem that such small particle diameter carriers cannot be sufficiently recovered from the surface of the image carrier.

[Problems to be Solved by the Invention] This invention provides that when development is performed on the surface of an image bearing member by a developing device using a developer containing a mixture of toner and carrier, the carrier is deposited on the surface of the image bearing member. It is an object of the present invention to solve the above-mentioned problems in a carrier recovery device that recovers the attached carrier from the surface of an image carrier when the carrier is attached.

That is, the present invention provides a two-component development type developing device that uses toner and carrier as the developer, and when developing is performed on the surface of an image bearing member using a carrier with a small particle size. An object of the present invention is to make it possible to reliably recover carriers with small particle diameters from the surface of an image carrier even if small carriers adhere to the surface of the image carrier.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a developing device that performs development on the surface of an image carrier using a developing device using a developer containing a mixture of toner and carrier. A brush provided with a brush made of flexible fibers having magnetism on its outer circumferential surface, in a carrier recovery device that collects carriers attached to the surface of an image carrier at a position downstream in the rotational direction of the image carrier from the region. A roller is provided to face the image carrier, a magnet is provided inside the brush roller, and the brush roller is rotated in a direction opposite to the rotational direction of the image carrier. The brush is brought into contact with the surface of the image carrier.

Here, the above-mentioned brush provided on the outer peripheral surface of the brush roller can be made of fibers made of magnetic fibers made by dispersing ferrite in resin, and usually the brush line is Use a brush with a diameter of 50 to 200 μm and a brush length of 5 to 10 mm.

In addition, when such a brush roller is rotated in the opposite direction to the rotation direction of the image carrier and the brush provided on this brush roller is brought into contact with the surface of the image carrier, the contact of the brush causes the surface of the image carrier to be In order to avoid disturbing the toner image formed on the surface, the circumferential speed of the brush roller is set to be approximately the same as the circumferential speed of the image carrier, and preferably the circumferential speed of the image carrier and the circumference of the brush roller are approximately the same. Speed ratio is 0.9~
Make it about 1.1.

Furthermore, when the brush provided on the brush roller is brought into contact with the surface of the image carrier, if the length of the brush that contacts the surface of the image carrier is not appropriate, the carrier may not be collected properly by the brush. , the image formed on the surface of the image carrier may be distorted, so the length of the brush may be
It is preferable that the distance be 0.5 to 1.5 mm longer than the distance to the surface of the image carrier.

[Function] In the carrier recovery device according to the present invention, as described above, a brush roller having a brush made of magnetic flexible fibers on the outer circumferential surface is provided to face the image carrier, and the brush roller is provided to face the image carrier. A magnet is provided inside the brush roller, and the brush roller is rotated in the opposite direction to the rotation direction of the image carrier, so that the brush stands up due to the magnetic force of the magnet, and the brush that stands up in this way is attached to the image carrier. comes into soft contact with the surface.

The magnetic force of the magnet reliably acts on the carrier attached to the surface of the image carrier through this brush, and even if the carrier attached to the surface of the image carrier has a small particle size due to this magnetic force, will be reliably collected by the brush.

In addition, as mentioned above, the brush that rises due to the magnetic force of the magnet comes into soft contact with the surface of the image carrier, and since the circumferential speeds of the brush roller and the image carrier are approximately equal, the toner image formed on the surface of the image carrier is is never disturbed.

[Example] Hereinafter, an example of the present invention will be specifically described based on the accompanying drawings.

In this embodiment, as shown in FIG. 1, a developing device (IO) using a developer (1) containing toner and a carrier (1a) is applied to the surface of the image carrier (2). In order to recover the carrier (1a) supplied to the surface of the image carrier (2) together with the toner when the development is performed, the development is performed on the surface of the image carrier (2) by the developing device (10). A carrier recovery device (20) is provided integrally with the developing device (10) at a position downstream from the developing region in the rotational direction of the image carrier (2).

Here, in the above-mentioned developer bag f (10), as shown in the figure, the developer (1) containing a mixture of toner and carrier (1a) is placed inside the developing bag by the rotation of the packet roller (11). The roller (12) is supplied to the surface of the developing roller (13) provided with the roller (12).

As the developing roller (13) to which the developer (1) is supplied in this manner rotates, the developer (1) supplied to the developing roller (13) is transferred to a roller provided inside the developing roller (13). Due to the magnetic force of the magnet roller (12), magnetic spikes are formed on the developing roller (13) and then transported to the image carrier (2), and the developer (1) is transferred to the image carrier (2). While being conveyed to
13) and the height regulating plate (14
) to regulate the height of this magnetic spike, and the image carrier (2)
The amount of developer (1) that is conveyed is adjusted.

Next, the height of the magnetic ears is adjusted by the height regulating plate (14) in this manner, and the developer (1) that has been conveyed to the image carrier (2) is brought to face the image carrier (2). The developing area near the north pole of the magnet roller (12) is brought into contact with the surface of the image carrier (2), and toner is supplied to the electrostatic latent image location formed on the surface of the image carrier (2). did.

Further, after the toner is supplied to the electrostatic latent image area formed on the surface of the image carrier (2) in this way, the developing roller (
13) The developer (1) remaining on the surface of this developing roller (
The developing roller (13) is guided into the developing device (10) as the magnetic roller (13) rotates, and the developing roller (1
3) Remove the developer (1) remaining on the surface of the developing roller (
13), returned to the developing device (10), stirred by the packet roller (11), and then supplied to the developing port roller (13) again.

Here, as described above, the developer (1) is brought into contact with the surface of the image carrier (2) in the form of magnetic spikes, and the toner is applied to the electrostatic latent image area formed on the surface of the image carrier (2). When supplying
The carrier (1a) may be supplied to the surface of the image carrier (2) together with the toner, and the carrier (1a) thus supplied to the surface of the image carrier (2) is The image carrier (2) is removed by the carrier recovery device (20) of
).

Here, in the carrier recovery device (20) of this embodiment, ferrite is dispersed in resin on the outer circumferential surface of a roller (22) made of a conductive non-magnetic material as a brush roller (21). A brush (23) made of magnetic fibers is used, and this brush roller (21) is placed downstream of the developing area of the developing device (10) in the rotational direction of the image carrier (2). The brush roller (21) is provided so as to face the image carrier (2) at a side position, and the brush roller (21) is set to have approximately the same circumferential speed as the image carrier (2). ) is now rotated in the opposite direction.

Further, a magnet (24) having N1 pole, Sli, and S2 pole is provided on the inner peripheral side of this brush roller (21).
The N1 pole of this magnet <24) is positioned to face the image carrier (2), while the magnet (24)
The S1 pole and the S2 pole of the image carrier <2> were placed adjacent to each other at a position away from the image carrier <2>.

In addition, at the position between the 81st pole and the S2 pole of the magnet 24) which are positioned adjacent to each other in this way,
The brush (23) provided on the brush roller (21)
) A collection roller (25) made of a conductive non-magnetic material is provided in contact with the collection roller (25), and a scraper (26) is brought into pressure contact with the peripheral surface of the collection roller (25).

Then, the carrier (1a) supplied to the surface of the image carrier (2) by the carrier recovery device (20) of this embodiment
) from the surface of the image carrier (2), move the brush roller (21) to the image carrier (2) as described above.
The image carrier (2
) in the opposite direction to the direction of rotation of this brush roller (
The brush (23) provided on the outer peripheral surface of the brush roller (21) is connected to the magnet (23) provided on the inner peripheral side of the brush roller (21).
4) The magnetic effect causes the ears to stand up.

Then, the bristled brush (23) is brought into soft contact with the surface of the image carrier (2) to which the carrier (1a) is attached, and the magnetic force of the magnet (24) is applied to
The brush (23) is applied to the carrier (1a) attached to the surface of the image carrier (2), and a bias voltage for carrier recovery is applied to the brush roller (21). Carrier attached to the surface of (
1a) was collected on the brush (23) of this brush roller (21).

The carrier (1a) thus attached to the surface of the image carrier (2) is transferred to the brush (2) of the brush roller (21).
3), the magnet (2)
4) is applied to the image carrier (23) through this brush (23).
The carrier (1a) attached to the surface of the image carrier 2) reliably acts on the carrier (1a), and due to the action of the electric field due to the bias voltage for carrier recovery applied to the brush roller (21), the carrier (1a) attached to the surface of the image carrier 2) is Even if the carrier (1a) has a small particle size, the brush (23) of this brush roller rough 21)
) will now be reliably collected.

Further, by setting the circumferential speed of the brush roller (21) to approximately the same speed as the circumferential speed of the image carrier (2), the brush (23), which has been raised up by the magnetic force of the magnet (24), is moved to the image carrier (2). ), the image formed on the surface of the image carrier (2) was not disturbed by the brush (23) that came into contact with it.

After the carrier (1a) attached to the surface of the image carrier (2) is collected by the brush (23) of the brush roller (21) in this way, the rotating brush roller (2)
1), the carrier (1a) is collected by the brush (2).
3) is guided to a position where the 81st and 82nd poles of the magnet (24) provided on the inner peripheral side of the brush roller (21) are adjacent to each other, and the repulsion magnetic field that acts between the S1 and 82nd poles causes , brush the recovered carrier (1a) (23)
81 of the magnet (24).
This brush (23) should be brought into contact with the circumferential surface of the collecting roller (25) at a position between the pole and 328i.

Then, the brush roller (21) is attached to this collection roller (25).
A carrier recovery bias voltage higher than the bias voltage applied to the brush (23) was applied to collect the carrier (1a) detached from the brush (23) onto the circumferential surface of the recovery roller (25).

After the carrier (1a) detached from the brush (23) is collected on the circumferential surface of the collection roller (25),
The scraper (26) pressed against the circumference of the recovery roller (25) scrapes off the carrier (1a) collected on the circumference of the recovery roller (25) from the circumference of the recovery roller (25). did.

[Effects of the Invention] As detailed above, in the carrier recovery device according to the present invention, the brush roller, which is provided with a brush made of magnetic flexible fibers on the outer circumferential surface, is arranged to face the image carrier. In addition, a magnet is provided inside the brush roller, and the brush roller is rotated in a direction opposite to the rotational direction of the image carrier, and the brush on this brush roller is raised by the magnetic action of the magnet. A raised brush is brought into soft contact with the surface of the image carrier, and the magnetic force of the magnet is applied to the carrier attached to the surface of the image carrier through this brush. Even if the attached carrier has a small particle size, it can now be reliably collected by the above-mentioned brush.

Further, since the brush raised up by the magnetic force of the magnet is brought into soft contact with the surface of the image carrier as described above, the toner image formed on the surface of the image carrier is not disturbed.

As a result, when the carrier collection device according to the present invention is used to collect the carrier attached to the surface of the image carrier, the toner image formed on the surface of the image carrier may be disturbed. Even carriers with small particle sizes can now be reliably recovered from the surface of the image carrier.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the state in which a carrier recovery device according to an embodiment of the present invention is used. (1)...Developer (1a)...Carrier (2)...Image carrier (10)...Developing device (20)...Carrier collection device (21)...Brush roller ( 23)...Brush (24)...
Magnet diagram 1

Claims (1)

[Claims] 1. At a position on the downstream side in the rotational direction of the image carrier from the development area where the surface of the image carrier is developed by a developing device using a developer containing a mixture of toner and carrier. In a carrier recovery device that recovers carriers, a brush roller having a brush made of magnetic flexible fibers on the outer peripheral surface is provided to face the image carrier, and a magnet is installed inside the brush roller. 1. A carrier recovery device characterized in that the brush roller is rotated in a direction opposite to the rotational direction of the image carrier so that the brush provided on the brush roller is brought into contact with the surface of the image carrier.