JPH04118677A - Developing device - Google Patents

Abstract

PURPOSE:To obtain an excellent color image by arranging the magnetic poles of the same polarity positioned on a downstream side in the rotating direction of a developing roller at a position where developer is not attracted by the action of magnetic force. CONSTITUTION:When the developer 2 is allowed not to be attracted to the developing roller 12 by the magnetic pole N4 positioned on the downstream side in the rotating direction of the roller 12, the quantity of the developer 2 supplied to the roller 12 is decreased, and then, a plate material 16 arranged between a bucket roller 13 and the magnetic pole N4 is made short in a length direction so that the developer 2 may sufficiently be supplied. The developer 2 held on the roller 12 is made in a magnetic brush state to be carried to an image carrier 3 side by the action of the magnetic force of a fixed magnetic pole 14. After the quantity of the developer 2 is regulated by a regulating mem ber 15, the brush of the developer 2 formed on the roller 12 is brought into contact with the surface of the image carrier 3 so that toner may be supplied to the spot of a latent image, thereby obtaining the excellent color image.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a developing device used in an image forming apparatus such as a copier or a printer. Then, the developer in the developer supply section is supplied to a developing roller having a fixed magnetic pole therein, the developing roller is rotated, and the supplied developer forms a magnetic brush by the magnetic action of the fixed magnetic pole. The present invention relates to a developing device that transports the image carrier toward the image carrier side.

[Prior art and its problems] Various developing devices have been used to perform development in image forming devices such as copiers and printers. In addition to a one-component development system that uses only a toner and a carrier, a two-component development system that uses a developer that is a mixture of toner and carrier is known.

Here, as shown in FIG. 2, in a developing device using a two-component developing method in which toner and carrier are mixed, the developer (2) in the developer supply section (11) is transferred to the developing roller (1).
A packet roller (13) is provided in the developer supply section (11) as a supply member (13) for supplying the developer to the developer supply section (11).
) inside the fixed magnetic pole (14).
It is known that the developing roller (12) is supplied with a developing roller (12).

In this developing device (1'), the developer (2) supplied from the packet roller (13) to the developing roller (12) as described above is transferred to a fixing device provided inside the developing roller (12>). The developer (2) in the developer supply section (11) is held on the developing roller (12) by the magnetic force of the magnetic pole (14), and the developer (2) in the developer supply section (11) is held on the developing roller (12) by the magnetic force of the fixed magnetic pole (14). By suctioning and holding the developer (2) on the developing roller (I2) as described above, the developing roller (12) is rotated.
Due to the magnetic force of the fixed magnetic pole (14), the image is conveyed to the image carrier (3) in the form of a magnetic brush.

Also, during the stage where the developer (2) held on the developing roller (12) is made into a magnetic brush and is transported to the image carrier (3) side, the developer (2) is transported by the regulating member (15). After controlling the amount of the developer (2), the developer (2) is transported to a developing area facing the image carrier (3) as the developing roller rough 12) rotates, and in this developing area, the developer (2) is transferred onto the developing roller (12). The magnetic brush of the formed developer (2) is brought into contact with the surface of the image carrier (3) to supply toner to the latent image area formed on the image carrier (3).

On the other hand, in recent years, image forming apparatuses such as those described above have become more color-oriented, and a plurality of developing devices are arranged around the image bearing member, and each developing device supplies toner of a different color to the image bearing member. , which was adapted to form color images, was developed.

However, in the conventional developing device (1'), the magnetic brush of the developer (2) formed on the developing roller (12) is brought into contact with the surface of the image carrier (3) as described above to remove the toner. Since the image is supplied to the image carrier (3), when the previous developing device (1'') performs development and the next developing device (1') develops a different color, the first developing device (1'') performs development. A magnetic brush formed on a developing roller (12) in the next developing device (1') comes into contact with the surface of the image carrier (3) to which toner has been applied by the next developing device (1'), and the image carrier Toners of different colors are supplied to the surface of the image carrier (3), causing color mixture in the formed image, and contact with the magnetic brush in this way may cause toners of different colors to be supplied to the surface of the image carrier (3).
) The toner applied to the surface of the paper was scraped off, causing problems such as a decrease in the density of the formed image.

Therefore, in the past, as mentioned above, the developing device (
1°) and the toner supplied from the magnetic brush formed on the developing roller (12) of the next developing device (1') are mixed. Color mixture may occur in the formed image, or the toner supplied to the surface of the image carrier (3) by the previous developing device (1') may be transferred onto the developing roller (12) of the next developing device (1'). Various methods have been considered to prevent scraping by the formed magnetic brush.

Such methods include providing a shutter in the developing device, or changing the angle of a magnetic roller installed inside the developing roller as shown in Japanese Patent Laid-Open No. 61-208063. Some devices are designed to prevent the developer from being conveyed to the image carrier by the developing roller, and some are designed to prevent the developer from being conveyed to the image carrier by moving the developing device away from the image carrier and moving the developing device away from the image carrier. There are known devices in which the magnetic brush of the developer formed on the image carrier does not come into contact with the image carrier.

However, in any of the above methods, it is necessary to provide a shutter, a means for changing the angle of the magnet roller, a means for moving the developing device, etc., which makes the device complicated and increases the cost. .

Also, if you change the angle of the magnetic roller or move the developing device as described above, when you return them to their original positions to perform development again, their positions will shift, causing the image to become distorted. There was also the problem that the formation could not be performed properly.

[Problems to be Solved by the Invention] The present invention rotates the supply member provided in the developer supply section as described above, and supplies the developer in the developer supply section to a developer having a fixed magnetic pole inside. feed to the roller,
It is an object of the present invention to solve the above-mentioned problems in a developing device in which the developing roller is rotated to convey the supplied developer to the image carrier side while forming a magnetic brush by the magnetic force of the fixed magnetic pole. This is a subject to be addressed.

That is, in the present invention, when a required number of developing devices as described above are provided around an image carrier to form a color image, the toner supplied to the surface of the image carrier by the previous developing device is Color mixing may occur in the image formed by mixing with toner supplied by the next developing device, or toner supplied to the surface of the image carrier by the previous developing device may form on the developing roller of the next developing device. It is an object of the present invention to prevent scraping by a magnetic brush applied by a magnetic brush by simple control.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, a supply member provided in a developer supply section is rotated,
The developer in the developer supply section is supplied to a developing roller which is provided with a fixed magnetic pole inside, the developing roller is rotated, and the developer supplied to the developing roller is applied to a magnetic brush by the magnetic action of the fixed magnetic pole. A developing device that conveys the image to the image carrier side while forming it faces the above-mentioned supply member. Magnetic poles of the same polarity are provided adjacent to each other in the rotational direction of the developing roller, and the magnetic pole located on the downstream side in the rotational direction of the developing roller is connected to the fixed magnetic pole in the developer supply section. The developer is disposed at a position where it is not attracted by magnetic force, and a control means is provided for slowing down or stopping the rotation of the supply member to stop the supply of developer from the supply member to the developing roller. .

[Function] In the developing device according to the present invention, when performing normal development, the supply member provided in the developer supply section is rotated in a normal state, and the developer accommodated in the developer supply section is transferred to this supply member. The developer is supplied from the supply member to the developing roller, and the developing roller to which the developer is supplied in this way is rotated, and the supplied developer is turned into a magnetic brush and conveyed to the image carrier side by the magnetic action of the fixed magnetic pole. Then, the magnetic brush of the developer is brought into contact with the surface of the image carrier, so that the toner is supplied to the latent image area formed on the image carrier.

On the other hand, when developing is not performed using this developing device,
The control means slows down or stops the rotation of the supply member so that the developer is not supplied to the developing roller from the supply member.

In addition, in this developing device, among the magnetic poles of the same polarity among the fixed magnetic poles provided at a position facing the supply member as described above, the magnetic pole located on the downstream side in the rotational direction of the developing roller is inserted into the developer supply section. Since the stored developer is arranged at a position where it is not attracted by magnetic force, the developer stored in the developer storage section is not supplied to the developing roller by the action of the fixed magnetic pole.

For this reason, if the rotation of the supply member is slowed down or stopped by the control means as described above so that no developer is supplied from the supply member to the developing roller, no developer is supplied to the developing roller and the developing A magnetic brush of developer is no longer formed on the roller, and toner is supplied from this developing device to the surface of the image carrier, causing color mixing with the toner supplied to the surface of the image carrier by the previous developing device. There is no possibility that the toner supplied to the surface of the image carrier by the previous developing device is scraped off.

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

As shown in FIG. 1, the developing device (1) in this embodiment also supplies the developer (2) in the developer supply section (11) to the developing roller (1'), similarly to the conventional developing device (1'). )
The developer supply section (1
1) A packet roller (13) is provided inside, and the packet roller (13) is rotated to supply the developer (2) in the developer supply section (11), which has a fixed magnetic pole (14) inside. It was arranged to supply the developing roller (12).

At a position where the fixed magnetic poles 14) provided inside the developing roller (12) face the packet roller (13), magnetic poles N of the same polarity are arranged adjacent to each other in the rotational direction of the developing roller (12). , , N4 are provided, and the developer (2) supplied from the packet roller (13) to the developing roller rough 12) as described above is transferred to the same polarity magnetic poles N3. N,
Among them, the developing roller (12) is held by the magnetic force of the magnetic pole N4 located on the downstream side in the rotational direction of the developing roller (12).

Here, in the developing device (1) in this embodiment, the above-mentioned magnetic poles of the same polarity N3. At N4, the magnetic force of the magnetic pole N4 located on the downstream side in the rotational direction of the developing roller (12) is weakened, and the position of this magnetic pole N4 is set to be lower than that of the conventional developing device (1°) shown in FIG. Laura (12)
The developer (2
) is prevented from being attracted to the developing roller (12).

Moreover, if the developer (2) in the developer supply section (11) is prevented from being attracted to the developing roller (12>) by the magnetic pole N4 located on the downstream side in the rotational direction of the developing roller (12), the developing roller (12) Since the amount of developer (2) supplied to the roller (12) decreases, in the developing device (1) of this embodiment, the plate material disposed between the packet roller (13) and this magnetic pole N4 The length of (16) is made shorter than that of a conventional developing device (1°) so that the developer (2) is sufficiently supplied from the packet roller (13) to the developing roller (12).

Then, the developer (2) supplied to the developing roller (12) by the packet roller (13) as described above is held on the developing roller (12) by the magnetic force of the magnetic pole N4 in the fixed magnetic pole (14>), By rotating the developing roller (12), the developer (2) held on the developing roller (12) is turned into a magnetic brush by the magnetic force of the fixed magnetic pole (14), and is applied to the image carrier (3) side. I had it transported.

Also, during the stage where the developer (2) held on the developing roller (12) is made into a magnetic brush and is transported to the image carrier (3) side, the developer (2) is transported by the regulating member (15). After controlling the amount of developer (2) to be applied, the developer (2) is transferred to the image carrier (3) as the developing roller (12) rotates.
is transported to a developing area facing the
A magnetic brush of developer (2) formed on the developing roller (12) is brought into contact with the surface of the image carrier (3) to supply toner to the latent image area formed on the image carrier (3). I did it like that.

After the toner is supplied to the latent image portion of the image carrier (3) in this way, the developer (2) on the developing roller (12) is transferred to the developing device as the developing roller (12) rotates. (1), and the magnetic pole N3. of the same polarity in the above fixed magnetic pole (14). At a location where N4 is adjacent to each other, the repelling magnetic field causes the developer (2) to separate from the developing roller (12) and return into the developer supply section (11).

On the other hand, when the developing device (1) does not perform development, the rotation of the packet roller (13) is controlled by a control means (not shown), and the rotation of the packet roller (13) is controlled by a control means (not shown).
Rotate at low speed or use a packet roller (13
) is stopped, and the packet roller (13
) to prevent the developer (2) from being supplied to the developing roller (12).

If the developer (2) is prevented from being supplied to the developing roller (12) from the packet roller (13) in this way, the developer (
2) is not supplied to the developing roller (12), the developer (2) held on the developing roller (12) by this magnetic pole N4 is transported as the developing roller (12) rotates, and the above-mentioned After being returned to the developing device (1), the developer (2) completely disappeared from the developing roller (12).

Therefore, even if the developing roller (12) rotates, the developer (2
) is not conveyed to the image carrier 3) side, and the magnetic brush of the developer (2) no longer comes into contact with the surface of the image carrier (3).

A plurality of the developing devices (1) are arranged around the image carrier (3), and each developing device (1) is connected to the image carrier (3).
When forming a color image by supplying toners of different colors to the image carrier (3), the portion where the toner is supplied to the image carrier (3) by the previous developing device (1) is the same as that of the subsequent developing device (1).
), in the subsequent developing device (1), the control means stops supplying the developer (2) from the packet roller (13) to the developing roller (12>), and this developing device A magnetic brush of the developer (2) was prevented from forming on the roller (12).

In this way, the toner supplied to the image carrier (3) by the earlier developing device (1) and the toner supplied by the later developing device (1) will not mix and cause color mixture. Furthermore, the image carrier (3) is
The toner supplied to the developing device (1) is no longer scraped off by the subsequent developing device (1), and a good color image can now be obtained.

[Effects of the Invention] As detailed above, in the developing device according to the present invention, the supply member provided in the developer supply section is rotated to supply the developer to the developing roller having a fixed magnetic pole inside. In supplying the developer, a control means is provided to reduce or stop the rotation of the supply member to stop the developer from being supplied from the supply member to the developing roller. Of the magnetic poles of the same polarity provided on the fixed magnetic poles adjacent to each other in the rotational direction of the roller, the magnetic pole located on the downstream side in the rotational direction of the developing roller is prevented from attracting the developer contained in the developer supply section. Therefore, when the supply of developer from the supply member to the developing roller is stopped by the control means, no developer is supplied to the developing roller at all, and a magnetic brush of developer is formed on the developing roller. lost.

Therefore, when a plurality of developing devices according to the present invention are arranged around an image carrier and a color image is formed by supplying toner of a different color from each developing device to the image carrier, the control as described above is required. By simply slowing down or stopping the rotation of the supplying member, a magnetic brush of developer is no longer formed on the developing roller, and the toner supplied to the image carrier by the previous developing device is mixed with the toner supplied to the image carrier by the subsequent developing device. This eliminates the possibility of color mixing occurring due to mixing with toner, or of toner being supplied to the image bearing member by a previous developing device being scraped off by a subsequent developing device.

As a result, when the developing device according to the present invention is used, the rotation of the supply member can be slowed down or stopped without changing the angle of the magnet roller or moving the developing device as in the conventional case. With simple control, it is now possible to obtain good color images.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing how a developing device according to an embodiment of the present invention is used, and FIG. 2 is a schematic sectional view showing how a conventional developing device is used. (1)...Developing device (2)...Developer (3)
... Image carrier (11) ... Developer supply section (1
2)...Developing roller (13)...Supplying member (packet roller) Fig.

Claims (1)

[Claims] 1. Rotate the supply member provided in the developer supply section to supply the developer in the developer supply section to the development roller, which has a fixed magnetic pole inside; In a developing device that transports the supplied developer to the image carrier side while forming a magnetic brush by the magnetic action of the fixed magnetic pole, the fixed magnetic pole at a position facing the supply member has a magnetic pole of the same polarity. are arranged adjacent to each other in the rotational direction of the developing roller, and the magnetic pole located on the downstream side in the rotational direction of the developing roller is arranged in a position where the developer contained in the developer supply section is not attracted by magnetic force. A developing device comprising: a control means for slowing or stopping the rotation of the supplying member to stop the supply of developer from the supplying member to the developing roller.