JPH0447733Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developing device installed in an image recording device such as an electrostatographic copying machine or a facsimile machine, and more specifically, the present invention relates to a developing device installed in an image recording device such as an electrostatographic copying machine or a facsimile machine. The present invention relates to a developing device having a developing roller in which a ear cutting magnet, a developing magnet, and a conveying magnet are arranged inside the developing sleeve to form a panicle cutting area, a developing area, and a conveyance area.

[Conventional technology]

The developer housed in the developing device has a certain number of sheets to be recorded (for example, 10,000 to 50,000 sheets) because the carrier in the developer deteriorates due to agitation in the developing device, aging, etc. At the time of maintenance, the developer in the developing device is removed and replaced with new developer.

Alternatively, on the production line, developer is supplied to the developing device for recording performance inspection, etc., but if the developer remains in the developing device, it will cause problems in terms of storage and transportation of the product. After completing the above-mentioned performance tests, etc., the developer is extracted from the apparatus.

Conventionally, when extracting this developer, the developing device is taken out of the machine, and while its developing sleeve is rotated, the developer that is magnetically attracted to the surface of the developing sleeve is suctioned and removed by a vacuum cleaner. situation.

[Problem that the invention attempts to solve]

In this way, when the developer around the developing sleeve is removed by suction while rotating the developing sleeve,
The developer housed in the developing device is sequentially conveyed to the developing magnet side by the magnetic force of the conveying magnet in the developing sleeve, and the entire amount of developer in the developing device is effectively drained out of the device. Although it is possible to extract the developer, it requires a vacuum cleaner to extract the developer, and having to carry it around is a pain for the service personnel who maintain the image recording apparatus.

[Means for solving problems]

The present invention was devised in view of the above-mentioned circumstances, and uses a unique technology that effectively utilizes the conveying magnetic poles necessary for development, allowing the development to be carried out without using a vacuum cleaner. The purpose is to make it possible to take out the entire amount of developer in the device.

In order to achieve the above object, the present invention has a magnet for cutting a magnet, a magnet for developing, and a conveyance area inside a rotatable developing sleeve in order to form a cutting area, a developing area, and a conveying area around the circumference of the developing sleeve. In a developing device having a developing roller on which a magnet is arranged, a conveying magnet immediately downstream of the developing magnet in the rotational direction of the developing sleeve is placed in a state in which a magnetic field is formed in the conveying area and in a state in which a magnetic field is not formed. The feature is that it can be switched freely.

[Effect]

According to the above characteristic structure, the conveyance magnet is made up of a permanent magnet and the permanent magnet is extracted from the developing sleeve, or the conveyance magnet is made up of an electromagnet and the electromagnet is demagnetized. By preventing the magnetic field generated by the conveying magnet from being formed around the sleeve, the developer is not conveyed to the conveying area by magnetic force, and as the developing sleeve rotates, the inside of the developing device is The developer is sequentially conveyed to the developing area around the developing sleeve, and the ears of the magnetic brush of the developer become enlarged in the developing area,
Eventually, the developer on the outer surface of the magnetic brush cannot be attracted and held by the magnetic force of the developing magnet, and the developer falls naturally.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 schematically shows an image forming section of an electrostatic photocopying machine (an example of an image recording device). Photoconductor 3 is installed inside the copying machine body in preparation for
are mounted horizontally, and around the photoreceptor 3 are a charging device 4, an exposure device 5, a developing device 6, a transfer device 7,
A recording paper separation device 8 and a cleaning device 9 are arranged in this order in the rotation direction R of the photoreceptor 3.

The developing device 6 can be inserted into and removed from the main body of the copying machine in the axial direction of the photoreceptor 3, and as shown in FIG. ) are built into the developing sleeve 16 with adjacent permanent magnets 12 to 15 having different magnetic poles, so that a cutting area, a developing area, and a conveying area are formed around the developing sleeve 16. On the other hand, an opening 11 is formed at a portion of the developing case 10 that accommodates the developer consisting of toner and carrier, corresponding to the photoreceptor 3, and the developing roller 17 is configured to face the opening 11. The developing roller 17 is attached to the developing case 10 so that the rotating direction Q of the developing sleeve 16 is the same as the rotating direction R of the photoconductor 3 at a portion corresponding to the photoconductor 3.
It is provided in

Two developer stirring tools 18 and 19 are built into the developing case 10, and the stirring tools 18 and 19 are built into the developing case 10.
A toner replenishment case 20 is connected to the developing case 10 in the upper part of the developer case 9, and the surplus developer cut by the ear cutting tool 21 is removed from the stirring tool 1.
A return plate 22 for refluxing the water is provided at the intermediate portion of 8 and 19.

In the developing roller 17 configured as described above, the conveying permanent magnet 14 is provided on the right downstream side in the rotational direction of the developing sleeve 16 with respect to the developing permanent magnet 13 so as to be freely insertable and removable in the rotational axis direction of the developing sleeve 16. The permanent magnet 14 is configured to be able to be switched between a state in which a magnetic field is formed in the conveying area of the sleeve circumference and a state in which it is not formed.

Specifically, a dovetail-shaped female fitting part a is formed in the permanent magnet holder 23 in the axial direction of the developing sleeve, and the female fitting part a is formed in the N pole portion of the conveying permanent magnet 14. A male fitting body b corresponding to the dovetail groove is formed so that the conveying permanent magnet 14 can be freely inserted and removed in the direction of the rotational axis of the developing sleeve 16, and as shown in FIG. By extracting the developer transporting permanent magnet 14 from the developing sleeve 16, a magnetic field by the transporting permanent magnet 14 is not formed in the area around the developing sleeve 16 corresponding to the arrangement of the transporting permanent magnet. .

That is, by extracting the conveying permanent magnet 14,
Developing sleeve 16 by the conveying permanent magnet 14
The developer transport function on the peripheral surface is now lost.

Therefore, the developing device 6 is taken out of the apparatus, and the conveying permanent magnet 14 that forms a magnetic field in the conveying area is extracted from the developing sleeve 16, and the magnetic field by the conveying permanent magnet 14 is transferred to the conveying area. When the developing roller 17 is rotated in the direction of the arrow Q in the same manner as during development, the permanent magnet 14 for conveying the developer has lost its ability to convey the developer. , the developer is no longer conveyed from the developing permanent magnet 13 to the portion corresponding to the conveying permanent magnet arrangement, and as the developing sleeve 16 rotates, the sleeve circumference by the developing permanent magnet 13 is no longer conveyed. The developer in the developing device is sequentially conveyed to the developing area, and the ears of the magnetic brush of the developer become enlarged in the developing area.
Eventually, the magnetic force of the permanent developing magnet 13 will no longer be able to attract and hold the developer on the outer surface of the magnetic brush, and the developer will naturally fall.

By continuing to rotate the developing sleeve 16 and appropriately receiving the free-falling developer into the developer recovery case, the entire amount of developer in the developing device 6 can be extracted to the outside of the developing case 10.

After extracting the developer, the conveying permanent magnet 14 is attached to the permanent magnet holder 23, the developing device 6 is returned to the inside of the device, and new developer is appropriately stored in the developing case 10. The developing device 6 can be involved in the development.

FIG. 4 shows a developing device 6 equipped with a developing roller 17 according to another embodiment. In this device, the conveying magnet 14 located directly downstream of the developing magnet 13 in the direction of rotation of the developing sleeve 16 is composed of an electromagnet, and the magnetic pole of the conveying magnet 14 is opposite to that of the developing magnet 13. In addition to being a pole, it is also provided so that it can be switched to demagnetize as necessary so as not to form a magnetic field in the conveying area.

That is, by placing the conveying magnet 14 under excitation, a magnetic field by the conveying magnet 14 is formed in the conveying area, and therefore, from the developing area side by the developing magnet 13 to the conveying area by the conveying magnet 14. The developer is transported to the side, and the transport magnet 14
By demagnetizing the developer, the conveyance function of the developer by the conveyance magnet 14 is lost, and the developer is no longer conveyed from the development area side to the conveyance area side.

Note that the rotation direction Q of the developing sleeve 16 may be set to be opposite to the rotation direction R of the photoreceptor 3 at a portion corresponding to the photoreceptor 3.

[Effect of idea]

As explained above, the developing device according to the present invention is
The present invention is characterized in that a conveying magnet immediately downstream of the developing magnet in the rotational direction of the developing sleeve can be freely switched between a state in which a magnetic field is formed in the conveying area and a state in which no magnetic field is formed. The magnetic field caused by the conveying magnet is reduced by configuring the conveying magnet with a permanent magnet and extracting the permanent magnet from the developing sleeve, or by configuring the conveying magnet with an electromagnet and demagnetizing the electromagnet. By preventing the developer from being formed in the conveying area around the sleeve and by preventing the developer from being conveyed to the conveying area by magnetic force, the developer in the developing device is The developer is sequentially conveyed to the developing area on the circumference of the developing sleeve corresponding to the developing magnet, and in the developing area, the ears of the magnetic brush of the developer become enlarged, and the developer on the outer surface of the magnetic brush is transferred by the magnetic force of the developing magnet. When the developer is no longer able to be absorbed and held, the developer will naturally fall, and by continuing to allow the developer to fall naturally, the entire amount of developer in the developing device can be extracted out of the device. As a whole, it is possible to make effective use of the original components of the developing device, that is, the conveying magnet, and to configure it with a permanent magnet and extract the permanent magnet from the developing sleeve, or to replace the conveying magnet with an electromagnet. By using unique technology such as switching the developing device to a demagnetized state, the entire amount of developer in the developing device can be effectively taken out of the device without using a vacuum cleaner as in the past. It became possible to do so.

[Brief explanation of the drawing]

FIG. 1 is a schematic overall view of the image forming section of the image recording device;
FIG. 2 is a sectional view of the developing device, FIG. 3 is a sectional view of the developing device with the conveying permanent magnet removed,
FIG. 4 is a sectional view of a developing device according to another embodiment. 12... Magnet for cutting ears, 13... Magnet for development, 1
4... Conveyance magnet (permanent magnet/electromagnet), 15...
...Transporting magnet, 16...Developing sleeve, 17...
developing roller.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In order to form a cutting area, a developing area, and a carrying area around the circumference of a rotatable developing sleeve, a cutting magnet, a developing magnet, and a carrying magnet are installed inside the developing sleeve. In a developing device having a developing roller arranged with a magnet, a conveying magnet immediately downstream of the developing magnet in the rotational direction of the developing sleeve is switched between a state in which a magnetic field is formed in the conveyance area and a state in which a magnetic field is not formed. A developing device characterized by being freely provided. (2) The developing device according to claim (1), wherein the conveying magnet is an electromagnet that can be demagnetized. (3) The developing device according to claim (1), wherein the conveying magnet is a permanent magnet that can be inserted into and removed from the developing sleeve.