JPS624706B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and device for discharging developer from a dry developing device used in electrophotographic copying machines, electrostatic printing machines, and the like.

A dry type developing device generally uses a dry type two-component developer consisting of a carrier made of a magnetic material and a toner made of a low melting point thermoplastic resin base mixed with a coloring dye, a pigment such as carbon black, etc. This dry two-component developer is stirred in the developing device,
Due to the friction between the carrier and the toner, the toner is charged to a polarity opposite to the polarity of the charge on the electrostatic latent image holding member that is the object to be developed. It is attached to the surface of the non-magnetic sleeve and conveyed by the magnetic brush device, and comes into contact with the surface of the electrostatic latent image holding member.
Here, the charged toner is attracted to the charge on the electrostatic latent image holding member and develops the electrostatic latent image. In a developing device that uses such a two-component developer, toner is consumed each time an electrostatic latent image is developed, so in general, toner is replenished so that the mixing ratio of toner and carrier is always at the desired value. It is configured to be Further, although the carrier is not consumed during development and is used repeatedly, it deteriorates due to stirring and the like, so it is necessary to replace it with a new one after a predetermined period of time or after a predetermined number of times of development. This carrier replacement is performed by collecting the developer containing the old carrier from the developing device and then loading the developer containing toner and new carrier in an appropriate mixing ratio.

Conventionally, as a recovery device for developer containing such an old carrier, Japanese Utility Model Publication No. 51-50533 discloses a developing device in which the scooping edge of the developer storage section is brought into contact with the circumferential surface of a non-magnetic developing drum. It has been proposed that the developing drum be attached to the developing drum and rotated to collect the developer containing the old carrier adhering to the surface of the developing drum. However, in this case, the magnet built into the developing drum remains fixed as in normal development, so the developer is transported only by the frictional force with the developing drum, and the transporting force is reduced. Extremely weak. For this reason, the collection efficiency is poor, and when the amount of developer becomes low, the developer attached to the vicinity of the magnetic poles of the magnet cannot be scooped up and conveyed to the edge position by the rotation of the non-magnetic developing drum alone. It has the disadvantage that it remains in the body and cannot be completely recovered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for discharging developer which eliminates the above-mentioned drawbacks and allows efficient and almost complete recovery of developer containing old carrier in a developing device.

In the present invention, a magnet and a non-magnetic sleeve covering the magnet are rotated relative to each other to discharge developer from a developing device which develops an electrostatic latent image using a magnetic brush tip while rotating the non-magnetic sleeve. The method for discharging the developer from the developing device by scraping off the magnetic brush tips adhering to the surface thereof is characterized in that the magnet and the non-magnetic sleeve are rotated together.

As described above, according to the method of the present invention, since the magnet and the non-magnetic sleeve are rotated together when collecting the developer, the conveyance force of the developer adhering to the surface of the non-magnetic sleeve is reduced. In addition, even if the amount of developer in the developing device decreases, it can be effectively attached to the surface of the non-magnetic sleeve and transported, and it has the advantage of being almost completely recovered.

On the other hand, in a developing device that uses a dry developer and includes a magnet and a non-magnetic sleeve, the magnet is fixed and the non-magnetic sleeve is rotated to cause the developer to act on the electrostatic latent image holding member. There are relatively many configurations. Further, in this case, from the viewpoint of the developing effect, it is desirable that the magnetic pole of the magnet be located close to the electrostatic latent image holding member.

Another object of the present invention is to provide a developing device that rotates a non-magnetic sleeve with a fixed magnet during normal development, but allows the magnet and non-magnetic sleeve to rotate together when collecting developer. The developer is appropriately constructed and arranged so that the developer can be efficiently and almost completely recovered, and the magnetic pole of the magnet can be easily fixed in a predetermined position relative to the electrostatic latent image holding member after the developer is recovered. There is no need to provide an evacuation device.

In order to discharge developer from a developing device which rotates a non-magnetic sleeve around a fixed magnet and develops an electrostatic latent image using a magnetic brush tip, the present invention provides a method for discharging developer from a developing device in which a non-magnetic sleeve is rotated around a fixed magnet. A developer discharging device that scrapes off the magnetic brush ears adhering to the developing device and discharges the magnetic brush from the developing device, comprising means for rotatably holding the magnet, and a magnet for selectively locking the magnet at a predetermined rotational position. The magnetic sleeve is characterized by comprising a locking means, and configured such that the magnet and the non-magnetic sleeve can rotate together when the magnet is not locked by the magnetic locking means.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view diagrammatically showing the structure of an example of a dry developing device embodying the present invention. This embodiment shows a case where the present invention is applied to an electrophotographic copying machine. The electrostatic latent image holding member 1 has a surface layer made of an insulating material or a photoconductive material on its outer periphery, and is rotatably attached to the main body of a copying machine (not shown) in the direction of arrow a, and is adapted to a well-known electrophotographic method. An electrostatic latent image is formed on the surface layer.

The developing device 2 includes a magnetic brush 3 and is detachably attached to the main body of the copying machine. The magnetic brush 3 is
A cylindrical non-magnetic sleeve 4 and a magnet bar 5 provided inside the sleeve are each rotatably pivoted to a developer container 6, and when developing an electrostatic latent image,
The non-magnetic sleeve 4 is rotated in the direction of the arrow b by a driving means (not shown), and the magnetic bar 5 is moved to a predetermined rotational position, that is, at least one of the magnetic poles is aligned with the electrostatic latent image holding member 1 by a magnetic locking means (to be described later). Fix it in a position facing the In this way, the developer 7 consisting of the magnetic carrier and toner stored in the bottom part of the container 6 is attached to the surface of the non-magnetic sleeve 4 in the form of spikes by the magnetic force of the magnet rod 5, and this is attached to the surface of the non-magnetic sleeve 4. The electrostatic latent image is conveyed by rotation in the direction of arrow b of 4 and brought into contact with the surface of the electrostatic latent image holding member 1, and the electrostatic latent image formed on the holding member 1 is developed. At the lower edge of the opening of the container 6 facing the electrostatic latent image holding member 1, there is a doctor blade 8 for regulating the amount of developer 7 conveyed by the magnetic brush 3, that is, the height of the magnetic brush ear. are fixed by screws 9. Further, at a position adjacent to the magnetic brush 3 at the bottom of the container 6, a stirring member 10 including stirring blades for stirring the developer 7 and frictionally charging the toner is rotatably provided.

The developer 7 that has been conveyed by the magnetic brush 3 and has completed its developing action is scraped onto the bottom of the container 6 by a developer scraping plate 11 as shown in FIG. This scraping plate 11 is pivotally attached to the container 6 so that it can swing freely, and its swinging tip comes into contact with or approaches the surface of the non-magnetic sleeve 4 due to its own weight. In this example, at the position where the developer adhering to the non-magnetic sleeve 4 is scraped off by the scraping plate 11, the adhesion force of the developer to the non-magnetic sleeve 4 due to the magnetic force is weakened, and the developer can be easily scraped off. In order to do this, no magnetic pole is provided in the part of the magnet bar 5 that faces the scraping position. In this way, the developer on the non-magnetic sleeve 4, which has once completed its developing action, is scraped off to the bottom of the container 6, and stirred again to cause new developer 7 to adhere to the surface of the non-magnetic sleeve 4.

On the other hand, in the upper part of the container 6, a hopper 12 for storing toner for replenishment is formed by the container 6 and a toner receiving plate 13 made of a leaf spring.
The entrance of No. 2 is configured to be openable and closable by a lid 14.
Additionally, a non-magnetic sleeve 4 is provided at the exit of the hopper 12.
A toner supply roller 15 is provided which rotates in the direction of arrow C at a predetermined speed in conjunction with the rotation of the toner supply roller 15 . This supply roller 15 is provided with a notch 15a for storing the toner in the hopper 12 and replenishing it to the bottom of the container, and is arranged so that the end of the toner receiving plate 13 engages with the notch 15a during rotation. do. In this example, in order to prevent undesired replenishment of toner from the hopper 12 to the bottom of the container 6, especially from the gap between the container 6 and the toner receiving plate 13, a hole is placed above the toner receiving plate 13. A rib 6a is provided on the container 6 constituting the hopper 12 with a length of about 5 to 20 mm protruding, and a sponge 16 is provided on the lower surface of the rib 6a.
Attach. In this way, the supply roller 1
5, the toner contained in the notch 15a is replenished to the bottom of the container 6, and the mixing ratio of the toner in the developer 7 and the magnetic carrier is always maintained at a desired value. As described above, in this example, the toner receiving plate 13 made of a leaf spring can be engaged with the notch 15a of the supply roller 15, so even if all the toner stored in the notch 15a does not fall, Since the toner is forcibly scraped out when the toner receiving plate 13 is engaged, it is possible to completely replenish the toner.
In addition, since the toner is powder, the supply roller 1
Only the toner near 5 is replenished, and a so-called bridge is formed in this area, and the remaining toner may not fall to the position of the supply roller 15. However, in this example, the toner receiving plate 13 is Since it vibrates every time it enters the notch 15a, this can break the bridge, making stable replenishment possible.

Further, an opening is formed in the center of the container 6 for accommodating a developer containing a new magnetic carrier at a predetermined mixing ratio, and this opening can be opened and closed by a developer replenishment lid 17. In this example, the supply lid 17 is integrally formed of a plastic material such as polypropylene, polyethylene, ABS, etc., and includes a portion 17a for attachment to the container 6, a thin portion 17b, and a lid portion 1.
7c, and the lid portion 17c is configured to be rotatable around the thin wall portion 17b. Further, as shown in detail in FIG. 3, the lid portion 17c has an inner rib 17d for replenishment and an outer rib 17 on both sides thereof.
In addition, the inner rib 17d is further formed with a recess 17f, which together with the container 6 constitutes a click mechanism, so that the lid portion 17c can be opened and closed reliably. By providing the inner rib 17d and the outer rib 17e in this way, the rotation angle (preferably about 60 degrees) of the lid portion 17c can be restricted by the outer rib 17e and the attachment portion 17a, and the When storing the developer, the lid portion 17c
Leakage from both sides can be effectively prevented by the inner ribs 17d. Moreover, the rotation of the lid portion 17c is achieved by using a thin wall portion 17 that is integrally molded without using a hinge.
Since it is done centering on b, the replacement developer will not spill out from the rotating part. Therefore, even an unskilled person can easily replace the developer without spilling it.

Next, the holding mechanism for the magnetic brush 3 and the magnetic locking means for the magnetic bar 5 described above will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a cross-sectional view of the magnetic brush 3 taken in the axial direction. Flanges 20a and 20b are provided at both ends of the non-magnetic sleeve 4, and a drive shaft 21 is fixed to one of the flanges 20a. ing. The drive shaft 21 is rotatably connected to the developer container 6 via a bearing 22, and the drive shaft 21 protruding outside the container 6 has a drive gear 23 connected to a drive means (not shown) and the developer device 2. A manual knob 24 is fixedly provided for manually rotating the drive shaft 21 when the drive means and the drive gear 23 are disconnected from each other by being removed from the copying machine main body. The magnet bar 5 is rotatably attached to the non-magnetic sleeve 4 by bearings 25a, 25b provided on the flanges 20a, 20b inside the non-magnetic sleeve 4, and is attached to the other flange 20.
The shaft 5a of the magnet bar 5, which is pivotally supported on the b side, passes through a holding plate 26 fixed to the container 6 and protrudes to the outside, and a ratchet 27 is fixed to this. The ratchet 27 is connected to the retaining plate 26 as shown in detail in FIG.
The magnet bar 5 is provided with one notch 27a that engages with a claw 28 provided on the outer surface of the magnet bar 5, and when engaged, does not rotate in the direction of the arrow b and keeps the magnet bar 5 at a predetermined rotational position, that is, as explained in FIG. As shown, at least one magnetic pole faces the electrostatic latent image holding member 1 and is locked in a position where there is no magnetic pole in the part opposite to the scraping position by the developer scraping plate 11, and the magnetic pole is locked in the direction of arrow b. It is possible to rotate in the opposite direction. In addition, the claw 28
is biased toward the center of the ratchet 27 by a spring 29.

Hereinafter, a description will be given of an operation for replacing deteriorated developer in the above-mentioned developing device.

First, before replacing the developer, in this example, the sixth
A discharge auxiliary plate 30 as shown in the figure is prepared. This ejection auxiliary plate 30 is provided with boss holes (or notches) 31a and 31b that fit into the heads of screws 9 for fixing the doctor blade 8 or attachment bosses provided on the doctor blade 8 at one end thereof,
When the boss holes 31a and 31b are fitted into the heads or bosses of the screws 9 and fixed to the developer container 6, the other end edge is in contact with the surface of the non-magnetic sleeve 4. This discharge auxiliary plate 30
After removing the developing device 2 from the copying machine main body,
It is attached to the developer container 6 as described above. next,
A developer tray (not shown) is placed below the discharge auxiliary plate 30 as a collection container, and the manual knob 24 is used to rotate the non-magnetic sleeve 4 in a direction opposite to the direction of arrow b (hereinafter referred to as the direction). When the non-magnetic sleeve 4 rotates in the direction, the magnetic carrier on the non-magnetic sleeve 4 and the magnet bar 5 are attracted to each other by magnetic force, so that the notch 27a of the ratchet 27
The lock with the claw 28 is released, and the magnetic bar 5 rotates together with the non-magnetic sleeve 4. Therefore, the developer on the non-magnetic sleeve 4 is attached not only by the frictional force with the non-magnetic sleeve 4 but also by an extremely strong force due to the added magnetic force of the magnetic bar 5, and as the non-magnetic sleeve 4 rotates. It will be transported with a load. The developer on the non-magnetic sleeve 4 first comes into contact with the developer scraping plate 11, which is pivotably attached to the developer container 6 and comes into contact with the non-magnetic sleeve 4 due to its own weight. Because it's close,
The developer transported with strong adhesion force separates the developer from the non-magnetic sleeve 4, and the developer is not scraped off. The developer on the non-magnetic sleeve 4 that has passed through the scraping plate 11 rides on the ejection auxiliary plate 30 provided in contact with the non-magnetic sleeve 4 and is scraped off. The portion of the non-magnetic sleeve 4 where the developer has been scraped off absorbs the developer remaining at the bottom of the container 6 again and conveys it to the position of the discharge auxiliary plate 30 .

As described above, in this example, by rotating the non-magnetic sleeve 4 in the direction, the magnet bar 5 is rotated together by the magnetic force of the magnetic carrier, so that the development on the non-magnetic sleeve 4 is prevented. The adhesion force of the developer and the conveying force of the developer due to the rotation of the non-magnetic sleeve 4 are increased, so that the developer can be efficiently and almost completely recovered.

After collecting the developer, remove the discharge auxiliary plate 30 from the container 6, open the developer replenishment lid 17, and put in a predetermined amount of developer containing a new magnetic carrier at an appropriate mixing ratio. Attach it to the main body.

In addition, in the past, new developer was applied using a magnetic brush 3.
However, in this case, the developer that was introduced first would stick to the magnetic brush 3 and block the inlet of the developer that was introduced later, making the operation much more difficult. It required a lot of skill. However, in this example, in addition to the opening of the magnetic brush 3, a dedicated developer inlet is provided at a position separated from the opening, and a developer replenishment lid 1 is provided to open and close the inlet.
Since the above-mentioned various devices have been applied to the device No. 7, anyone can easily replace the developer.

After the developer is replaced, the magnetic bar 5 of the developing device 2 attached to the copying machine body is not necessarily locked at a predetermined rotational position. However, even if it is not at the predetermined rotational position, as the non-magnetic sleeve 4 rotates in the direction of arrow b during development of the electrostatic latent image, the magnet bar 5 is also integrated by the magnetic force with the magnetic carrier. Since the magnet bar 5 rotates with the movement of the magnet bar 5, the ratchet 27 and the pawl 28 engage with each other within one rotation of the magnet bar 5, and are automatically locked at a predetermined rotational position.

In addition, in the developer recovery work mentioned above,
Although the ejection auxiliary plate 30 was used, the doctor blade 8
If it is constructed so that it can move toward and away from the non-magnetic sleeve 4, it can also function as the ejection auxiliary plate 30. In addition, to recover deteriorated developer,
In addition to the saucer (not shown), as shown in FIG.
If a collection container 34, such as a plastic bag, is prepared on the entrance side and has holes 32a and 32b for fixing it to the developer container 6 together with the auxiliary plate 30, and a fitting type fastener 33, and the developer is collected in this container, the developer can be collected. You can work extremely cleanly without scattering. Furthermore, as shown in FIG. 8, a frame 35 is provided on the auxiliary plate 30, and a boss 36 is provided on this
A, 36b are provided protrudingly, and the collection container 34 shown in FIG.
It is also possible to attach a container 34' similar to the above to the developer container 6 together with the auxiliary plate 30 with the entrance open.

As described above, according to the present invention, since the non-magnetic sleeve and the magnet are rotated together when collecting the developer, the deteriorated developer can be efficiently and almost completely discharged. .
Furthermore, by providing means for locking the magnet at a predetermined rotational position, the magnet at any rotational position can be automatically set to a predetermined rotational position after the developer is replaced.

It should be noted that the present invention is not limited to the above-mentioned example, and can be modified or changed in many ways.
For example, the present invention is effectively applicable not only to a two-component developer containing a magnetic carrier and a toner, but also to a single-component developer. Furthermore, in the above-described example, when the non-magnetic sleeve 4 is manually rotated, the magnet bar 5 is rotated together by the magnetic force of the magnetic carrier, but the non-magnetic sleeve 4 and the magnet bar 5 are By interposing a one-way clutch between them, it is possible to ensure that the non-magnetic sleeve 4 and the magnetic bar 5 rotate integrally during recovery.

[Brief explanation of the drawing]

FIG. 1 is a sectional view diagrammatically showing the configuration of an example of a developing device embodying the present invention, FIG. 2 is an external perspective view of the developer scraping plate shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view of the magnetic brush cut in the axial direction to explain the holding mechanism of the magnetic brush, FIG. 5 is an external view of the locking means of the magnetic bar, and FIG. The figure is an external perspective view showing the structure of an example of a discharge auxiliary plate used during developer recovery work, FIG. 7 is an external perspective view showing the structure of an example of a collection container, and FIG. It is an external perspective view which shows the structure of another example of a container. 1... Electrostatic latent image holding member, 2... Developing device, 3
...Magnetic brush, 4...Nonmagnetic sleeve, 5...
Magnetic bar, 6...Developer container, 7...Developer, 8...
Doctor blade, 9... Screw, 10... Stirring member, 11... Developer scraping plate, 12... Hopper, 13... Toner receiving plate, 15... Toner supply roller, 16... Sponge, 17... Developer supply lid, 20a, 20b...flange, 21...drive shaft, 22...bearing, 23...drive gear,
24...Manual knob, 25a, 25b...Bearing, 26...Holding plate, 27...Ratchet, 28
...Claw, 29...Spring, 30...Ejection auxiliary plate, 3
1a, 31b...boss hole, 32a, 32b...
Hole, 33... Fastener, 34, 34'... Recovery container, 35... Frame, 36a, 36b... Boss.

Claims (1)

[Claims] 1. A magnet and a non-magnetic sleeve covering the magnet are relatively rotated to discharge the developer from a developing device which develops an electrostatic latent image using a magnetic brush tip. A method for discharging a developer, which scrapes off magnetic brush ears adhering to the surface of the developer while rotating and discharges the developer from a developing device, the method comprising rotating the magnet and a non-magnetic sleeve together. 2. In order to discharge developer from a developing device that rotates a non-magnetic sleeve around a fixed magnet and develops an electrostatic latent image using a magnetic brush tip, the developer is attached to the surface of the non-magnetic sleeve while being rotated. A developer discharging device that scrapes off the magnetic brush tip and discharges it from the developing device includes means for rotatably holding the magnet, and magnet locking means for selectively locking the magnet at a predetermined rotational position. and
A developer discharging device characterized in that the magnet and the non-magnetic sleeve are configured to rotate together when the magnet is not locked by the magnet locking means.