JP2606877B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to, for example, an electrostatic transfer type copying machine or a laser printer, and is used for developing an electrostatic latent image or the like formed on a recording medium. The present invention relates to a developing device.

[Conventional technology]

In a copying machine or the like, a toner made of a color pigment is adhered to the electrostatic latent image for the purpose of visualizing the electrostatic latent image formed on the recording medium. In this case, in order to visualize the electrostatic latent image not only in black but also in each color, a plurality of developing devices containing toners of various colors are provided inside the copying machine. The developing device is configured to be used selectively.

For example, when forming a full color, a developing device containing cyan, magenta, yellow, and, if necessary, a black toner is separately provided, and an electrostatic latent image on a recording medium that has been color-separated through a filter of each color is provided. Developing with the toner of each color described above, the toner of each color is superimposed on the recording medium to obtain a full-color copy image.

Therefore, the developing device needs to be configured so that the toner does not adhere to the electrostatic latent image when not used for development.

Conventionally, in order to prevent the toner of the developing device that is not subjected to development from adhering to the electrostatic latent image on the recording medium, conventionally, for example, switching is performed so as to change the developing gap, that is, the distance between the recording medium and the developing unit of the developing device. In general, the configuration is such that the toner is not sent to the developing area facing the recording medium.

However, with the above-described configuration, when the developing gap is switched so that the developing device is not used for the development, the developing condition varies, which tends to cause a change in image density. As described above, unless the positioning of the developing gap is performed accurately, a normal image cannot always be formed.

Further, in a developing device adopting the magnetic brush developing method, the position of the magnet constituting the developing unit is shifted so that the magnetic brush does not come into contact with the recording medium. When the position is shifted, not only does the image density change, but when a two-component type developer is used, the carrier adheres to the recording medium.
The image quality will be significantly reduced.

Therefore, a stirring roller is provided in a developer supply passage for supplying the developer to a developing magnet roller which is arranged opposite to the recording medium and performs development, and a slit is formed concentrically with the outer periphery of the stirring roller. The developer supply passage is closed or opened by a shutter mechanism whose rotation can be controlled, and the developer fed through the developer supply device is applied to a magnet type developer magnet roller. It is conceivable that the electrostatic latent image on the recording medium is developed by developing the developer, and the developer after the development is pumped up by the developing magnet roller and transported to the place where the developer is stirred by the transporting magnet roller. .

As a result, without changing the developing gap,
It is possible to prevent toner of the developing device that is not used for development from adhering to the electrostatic latent image on the recording medium.

[Problems to be solved by the invention]

However, in the case where the developer after being pumped up by the developing magnet roller is transported to the stirring roller by the transporting magnet roller as described above, the developer is transported by the transporting magnet roller. When the developer is scraped off from the transfer magnet roller by the scraper, the amount of developer rising at the developer release magnetic pole formed on the transfer magnet roller is small, and the developer release magnetic pole and the developer transfer passage are removed. The developer is magnetically attracted in a protruding state in the gap between the developer transport magnetic pole formed before the developer transfer magnetic pole and the developer release magnetic pole on the transport magnetic roller and the developer transport magnetic pole before the developer release magnetic pole. The developer that is magnetically attracted in a state in which it is in the middle cannot be sufficiently scraped off by the scraper. It is conceivable that the magnetic force of the developer release magnetic pole is set to be large to increase the amount of developer spikes, but in this case, the developer is excessively magnetically attracted to the transfer magnet roller. On the contrary, the scraper cannot be sufficiently scraped off by the scraper.

As described above, if the developer conveyed by the conveying magnet roller cannot be sufficiently scraped off by the scraper, the developer that has not been scraped off by the scraper will have the developer release magnetic pole and the developer in front of it. Since such a developer remains between the magnetic poles of the carrier or passes through a gap of about 0.2 mm formed between the scraper and the magnet roller for the carrier, stress is accelerated in such a developer, and This leads to a problem that the life is greatly shortened.

Further, as a developer, a toner composed of a toner and a carrier is used.
When developing using a component-based developer, the carrier tends to deteriorate, and it is necessary to periodically replace the developer in the developing tank with a new developer in order to obtain a stable copy image. is there. When replacing such a developer,
The developing magnet roller and the transporting magnet roller are rotated together, the developer stored in the developer is pumped up by the developing magnet roller, and the developer is transported to the developer releasing magnetic pole by the transporting magnet roller. From the opening at the upper end of the developing tank.

However, as described above, if the developer is magnetically attracted between the developer release magnetic pole of the transport magnet roller and the developer transport magnetic pole in front of the developer release magnetic pole, the developer can be sufficiently removed. Can not do,
A large amount of deteriorated developer, such as a large amount of developer remaining between the developer release magnetic pole and the developer transport magnetic pole in front of it, or the developer entering between the scraper and the transport magnet roller. Will remain inside.

In this way, when a large amount of deteriorated developer remains in the developing tank, a new developer accommodated in the developing tank becomes
Mixing with deteriorated residual developer, and even though the developer in the developing tank is replaced with a new developer, the density of the copied image is reduced or the carrier adheres to the recording medium and the image quality is reduced. Such a problem occurs.

[Means for solving the problem]

In order to solve the above-described problems, a developing device according to the present invention conveys a developing magnet roller that is arranged opposite to a recording medium and performs development, and a developed developer that is drawn up by the developing magnet roller. And a scraper for scraping off the developer magnetically attracted by the transfer magnet roller, and a magnetic pole formed on the transfer magnet roller. A developer releasing magnetic pole for releasing the developer from the transporting magnet roller and a developer transporting magnetic pole formed in front of the developer releasing magnetic pole on the developer transporting path are formed between the two magnetic poles. The angle between the two magnetic poles is set so that the state is formed almost continuously, and the developer release magnetic pole at the tip of the scraper is used to carry the developer. It is characterized in that it is set to be close positions than the magnetic poles.

As described above, in a case where the spike state of the developer is formed almost continuously between the developer release magnetic pole formed on the transport magnet roller and the developer transport magnetic pole in front of the developer release magnetic pole. For example, if the magnetic force of the developer release magnetic pole and the developer transport magnetic pole is set to 500 gauss, and the outer diameter of the transport magnet roller is set to a diameter of 35 mm, the above-described developer release magnetic pole and the front thereof Is set within 40 °.

(Operation)

As described above, the configuration is such that the state of standing of the developer is substantially continuously formed between the developer release magnetic pole formed on the transport magnet roller and the developer transport magnetic pole in front of the developer release magnetic pole. In addition, a large amount of developer spikes are formed between the developer release magnetic pole and the developer transport magnetic pole in the transport magnet roller.

As a result, the developer magnetically attracted onto the transfer magnet roller can be sufficiently scraped off by the scraper. In addition, the tip of the scraper is set so that the developer release magnetic pole is closer to the developer transport magnetic pole, so the scraper is magnetically attracted to the transport magnet roller when the developer is released. Scrape off the developer. That is, since the released developer is scraped off in a good standing state by setting the gap angle, the scraping effect is promoted.

Therefore, when the developer is transported by the transport magnet roller, the developer remains between the developer release magnetic pole and the developer transport magnetic pole or passes through a gap formed between the scraper and the transport magnet roller. Since such a situation does not occur, the stress of the developer is suppressed, and the life of the developer can be extended.

Further, when the developer in the developing tank is periodically replaced, the state of standing of the developer is obtained also between the developer releasing magnetic pole and the developer carrying magnetic pole, so that the work of removing the developer is remarkably performed. In addition to being smooth and easy, it is possible to take out all of the developer without leaving it.

〔Example〕

One embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

As shown in FIG. 1, inside a developing tank 1 in which a developer is stored, the developer is arranged to face a photoreceptor 3 which is a recording medium, and a magnetic brush is formed on the developer by a magnetic force to form a photoreceptor. A magnet type developing magnet roller 2 for performing development by making contact with the electrostatic latent image on 3 is rotatably mounted.

The developing magnet roller 2 has a rotatable cylindrical non-magnetic sleeve 2a whose outer peripheral portion is made of Al or the like. Inside the non-magnetic sleeve 2a, a magnet 2b whose periphery is magnetized to each pole is incorporated, and these magnets 2b form four magnetic poles N11, S11, N12, and S12, and the N 2 of the magnet 2b. The pole (N11) is fixed so as to form a main pole and face the photoconductor 3.

With this configuration, when the non-magnetic sleeve 2a rotates with respect to the fixed magnet 2b,
The developer magnetically adsorbed on the surface of the non-magnetic sleeve 2a is transported by the non-magnetic sleeve 2a while the magnetic pole N1
A magnetic brush of a developer is formed on the outer peripheral surface of the non-magnetic sleeve 2a corresponding to 1, S11, N12, and S12. This magnetic brush is the main pole (N11) of the magnet 2b facing the photoreceptor 3.
Are formed in a spike shape along the magnetic force of the photoconductor 3, and the photoconductor 3 is developed by rubbing the electrostatic latent image formed on the photoconductor 3 with the spike.

Above the developer magnet roller 2, a magnet for transporting the developed developer pumped up by the developing magnet roller 2 to a portion of a scraper 7 provided for scraping off the developer. A transfer type magnet roller 6 is attached.

The transfer magnet roller 6 has substantially the same configuration as the development magnet roller 2 described above, except for the difference in the number of magnetic poles and the like.

That is, there is a magnet 6b having a developer release magnetic pole S23 and the like on the outer periphery, and the magnet 6b allows the five magnetic poles S21, N21, S22, N22, S23 to face the developer transport passage Y.
Is formed and the magnet in this fixed state
A nonmagnetic sleeve 6a is rotatably fitted on the outer periphery of 6b.

As described above, the magnetic poles S21 and N disposed on the developer conveying path Y around the conveying magnet roller 6 are disposed.
At 21, S22, N22, and S23, a developer release magnetic pole S23 for releasing the developer from the transfer magnet roller 6, and a developer transfer formed before the developer release magnetic pole S23 on the developer transfer path Y The magnetic pole N22 is formed of the magnetic poles S23 and N22 so that the spike state of the developer formed by being magnetically attracted to the magnetic poles S23 and N22 is almost continuously formed between the magnetic poles S23 and N22. The gap angle is set.

Specifically, when the magnetic force of the developer release magnetic pole S23 and the magnetic force of the developer carrying magnetic pole N22 are each 500 gauss and the outer diameter of the carrying magnet roller 6 is 35 mm,
The gap angle θ between the developer release magnetic pole S23 and the developer carrying magnetic pole N22 is set within 40 ° (θ ≦ 40 °). As a result, the spike state of the developer is formed almost continuously between the developer release magnetic pole S23 and the developer carrying magnetic pole N22. If the magnetic force of the developer release magnetic pole S23 and the developer carrying magnetic pole N22 exceeds 500 gauss, the developer on the carrying magnet roller 6 is magnetically attracted too much, making it difficult for the scraper 7 to scrape off the developer. Become. Therefore, it is desirable that the magnetic force of at least the developer releasing magnetic pole S23 and the developer carrying magnetic pole N22 be magnetized to 500 gauss or less.

By rotating the non-magnetic sleeve 6a with respect to the fixed magnet 6b, the transfer magnet roller 6 can transfer the developer in a state where the developer is magnetically attracted to the surface of the non-magnetic sleeve 6a. ing.

Near the top of the transfer magnet roller 6, the tip of a scraper 7 for scraping off the developer magnetically attracted to the surface of the nonmagnetic sleeve 6 a is attached to the nonmagnetic sleeve 6 a of the transfer magnet roller 6. It is provided close to the surface with a slight gap (about 0.2 mm). The scraping surface of the scraper 7 is formed so as to be inclined downward from the front end to the rear end.
The rear end of the scraper 7 is extended to the vicinity of the below-described stirring section for stirring the developer. The scraper 7 is provided between the three members of the magnet roller 6 for conveyance, the stirring roller 9 and the magnet roller 2 for development, and has a partition part for partitioning these members. The gap between the portion of the scraper 7 other than the tip portion and the transfer magnet roller 6 is set to about 0.5 mm.

Above the scraper 7, a toner stirring roller 8 for stirring and mixing the toner supplied from the toner box 14 and the developer in the developing tank 1 is in a state close to the scraping surface of the scraper 7. It is rotatably attached with. And the toner in the toner box 14 is
The toner is supplied to the toner stirring roller 8 in the developing tank 1 based on a command from the toner concentration control means.
, The toner and the developer are stirred and mixed, and sent to the stirring section along the scraper 7.

The above-described stirring unit is rotatably provided with a stirring roller 9 and is fitted concentrically around the outer periphery of the stirring roller 9.
A cylindrical shutter 10 having slits 10a and 10b on opposite circumferential walls is provided. The stirring roller 9 is disposed in the middle of a developer supply passage Z for circulating and supplying the developer conveyed by the conveying magnet roller 6 to the developing magnet roller 2. The rotation of the shutter 10 and the stirring roller 9 is controlled independently of each other. When the slits 10a and 10b of the shutter 10 are set to open the developer supply passage Z as shown in FIG. While the supply of the developer to the roller 2 is controlled, the shutter 10 rotates by an angle of about 90 ° from the state shown in FIG. When both are set to the closed state, the supply of the developer is stopped.

During the development of the electrostatic latent image formed on the photoreceptor 3, only the necessary developing device has its shutter 10
Is set to the open state, the supply of the developer to the developing magnet roller 2 is continued, and at the same time when the development of the electrostatic latent image on the photoconductor 3 is completed, the shutter 10 is rotated by about 90 °,
The slits 10a and 10b of the shutter 10 are connected to the curved portion 1a of the developer 1.
And closed by the partition of the scraper 7,
The developer supply passage Z is shut off by the component wall of the shutter 10, and the developer supply passage Z
The supply of the developer to the developing magnet roller 2 is stopped by closing the shutter.

A regulating doctor blade 5 for regulating the supply amount of the developer magnetically attracted to the developing magnet roller 2 is provided near the end of the developer supply passage Z. The blade 5 is provided with a toner concentration detection sensor 13.

On the other hand, an upper lid 15 is provided at the upper end opening of the developing tank 1, and the upper lid 15 covers and closes the upper opening of the developing tank 1 except for the toner supply port 16 from above. Further, a toner box 14 is provided on the developing tank 1, and the toner contained in the toner box 14 can be supplied to the inside of the developing tank 1 at any time through the toner supply port 16. I have.

In the above configuration, when the non-magnetic sleeve 2a of the developing magnet roller 2 is rotated in the direction of the arrow in FIG. 1 with the developer, the non-magnetic sleeve 2a is formed by being magnetically attracted to the surface of the non-magnetic sleeve 2a. A developer magnetic brush rubs the electrostatic latent image formed on the photoconductor 3 to perform development.

The developer after development is pumped up while being magnetically attracted by the rotation of the non-magnetic sleeve 2a of the developing magnet roller 2, and the developer on the non-magnetic sleeve 2a reaches the position of the magnetic pole N12. Then, the magnetic force is attracted by the magnetic force of the magnetic pole S21 of the magnet 6b of the transfer magnet roller 6 close to the development magnet roller 2, and the transfer from the development magnet roller 2 to the transfer magnet roller 6 is performed.

The developer magnetically attracted to the transfer magnet roller 6 is magnetically attracted to the surface of the non-magnetic sleeve 6a with the rotation of the non-magnetic sleeve 6a rotating in the direction of the arrow, and the developer is released. It is transported to the vicinity of S23.

At this time, at each of the magnetic poles S21, N21, S22, N22, and S23 formed on the transfer magnet roller 6, a developer release magnetic pole S23 for releasing the developer from the transfer magnet roller 6, and a developer release magnetic pole S23 S23 developer transfer path Y
The angle between the magnetic poles S23 and N22 is set so that the developer carrying magnetic pole N22 formed on the upper side is almost continuously formed between the magnetic poles S23 and N22. Therefore, the developer transported by the rotation of the non-magnetic sleeve 6a is developed in a relatively wide area near the developer release magnetic pole S23 and the developer transport magnetic pole N22 and further between the magnetic poles S23 and N22. A continuous standing state of the agent is obtained.

As described above, when the spike state of the developer is obtained in a wide area from the developer release magnetic pole S23 of the transfer magnet roller 6 to the developer transfer magnetic pole N22, the developer is turned along with the rotation of the non-magnetic sleeve 6a. The tip of the scraper 7 is sufficiently scraped off. When scraping off, the tip of the scraper 7 is set such that the developer release magnetic pole S23 is located closer to the developer carrying magnetic pole N22, so that the scraper 7 is turned off when the developer is released. The developer magnetically attracted to the transfer magnet roller 6 is scraped off. That is, since the released developer is scraped off in a good standing state by setting the gap angle, the scraping effect is promoted.

The developer scraped off by the scraper 7 is stirred and mixed by the toner stirring roller 8 with the toner replenished from the inside of the toner box 14 through the toner supply port 16, and then is stirred along the scraping surface of the scraper 7. Will be transferred to

In the stirring section, when the shutter 10 is rotated and set to the open state as shown in FIG. 1, the developer flows into the stirring roller 9 from the slit 10a on the entrance side of the shutter 10, and the developer here. Is stirred. Then, the stirring roller 9
As a result, the developer is sent out from the slit 10b on the exit side of the shutter 10, and is sent to the developing magnet roller 2 through the developer supply passage Z, and is again subjected to development by the developing magnet roller 2.

To end the development, the developer supply passage Z is shut off by rotating the shutter 10 by about 90 °. As a result, the developer is not sent to the developing magnet roller 2, so that no magnetic brush is formed on the non-magnetic sleeve 2 a of the developing magnet roller 2, so that the photoconductor 3 is not developed.

Next, when the developer inside the developing tank 1 is newly replaced, the toner box 14 and the upper lid 15 are removed from the developing tank 1, and the upper end opening of the developing tank 1 is opened.

Then, after replacing the developing tank 1 upside down as shown in FIG. 2, the developing magnet roller 2 and the conveying magnet roller 6 are both rotated in the arrow direction. Then, the developer stored in the developing section of the developing tank 1 is drawn out by the developing magnet roller 2, further conveyed by the conveying magnet roller 6, and is moved from the opening of the developing tank 1 in the direction of arrow A. Is discharged to At this time,
Since the developer is formed in a spike shape over a wide area between the developer release magnetic pole S23 and the developer transport magnetic pole N22 of the transport magnet roller 6, the developer transported by the transport magnet roller 6 is formed. Is sufficiently scraped off by the tip of the scraper 7 and discharged in the direction of arrow A. If the magnetic force of the developer releasing magnetic pole S23 and the developer carrying magnetic pole N22 is set to a relatively weak magnetic force of 500 gauss or less, the work of taking out the developer from the developing tank 1 can be performed more smoothly and easily. Becomes

〔The invention's effect〕

As described above, the developing device according to the present invention includes, as described above, a developing magnet roller that is arranged to face a recording medium and performs development, and a transporting device that transports the developed developer drawn up by the developing magnetic roller. What is claimed is: 1. A developing device comprising: a magnet roller; and a scraper for scraping off a developer magnetically attracted by the transfer magnet roller, wherein the transfer magnet roller includes a magnetic pole formed on the transfer magnet roller. The developer release magnetic pole that releases the developer from the developer release magnetic pole, and the developer transport magnetic pole that is formed in front of the developer release magnetic pole on the developer transport path, the developer standing state is almost continuous between these two magnetic poles The angle between the two magnetic poles is set so that the magnetic flux is formed at the same time. At the tip of the scraper, the developer release magnetic pole is closer than the developer carrying magnetic pole. Is a configuration that is set to be the position.

As a result, the spike state of the developer is formed almost continuously between the developer release magnetic pole formed on the transfer magnet roller and the developer transfer magnetic pole in front of the developer release magnetic pole. As a result, a large amount of spikes of the developer are formed at the release portion, and the developer magnetically attracted onto the transfer magnet roller can be sufficiently scraped off by the scraper.

In addition, the tip of the scraper is set so that the developer release magnetic pole is closer to the developer transport magnetic pole, so the scraper is magnetically attracted to the transport magnet roller when the developer is released. Scrape off the developer. That is, since the released developer is scraped off in a good standing state by setting the gap angle, the scraping effect is promoted.

Therefore, when the developer is transported by the transporting magnet roller, a large amount of the developer remains between the developer releasing magnetic pole and the developer transporting magnetic pole in front of the developer releasing pole, or is formed between the scraper and the transporting magnet roller. Since the developer does not pass through the gap, the stress of the developer is suppressed, and the life of the developer can be extended. Also, when the developer in the developing tank is periodically replaced, a large amount of developer spike is formed between the developer release magnetic pole and the developer transport magnetic pole in front of the developer release magnetic pole. The operation of scraping off and removing the developer becomes extremely smooth and easy, so that the developer does not remain on the conveying magnet roller, and the developer can be reliably removed with almost no remaining.
As a result, the deteriorated developer in the developing tank does not mix with the new developer, so that the effect of maintaining high copy image quality can be achieved.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view showing the entire structure of a developing device, and FIG. 2 is a diagram for newly replacing a developer in a developing tank. FIG. 5 is an explanatory diagram illustrating a state of the developing device at the time. 1 is a developing tank, 2 is a developing magnet roller, 2a is a non-magnetic sleeve of the developing magnet roller, 2b is a magnet of the developing magnet roller, 3 is a photoconductor (recording medium),
Reference numeral 6 denotes a transfer magnet roller, 6a denotes a non-magnetic sleeve of the transfer magnet roller, 6b denotes a magnet of the transfer magnet roller, 7 denotes a scraper, 8 denotes a toner stirring roller, 9 denotes a stirring roller, 10 denotes a shutter, and 14 denotes toner. The box 15 is the top lid. Y is a developer conveyance passage, and Z is a developer supply passage. S21, N21, S22, N22, and S23 are magnetic poles of the conveying magnet roller. Of these magnetic poles, N22 is a developer conveying magnetic pole, and S23 is a developer releasing magnetic pole.

Claims (1)

(57) [Claims] A developing magnet roller disposed opposite to the recording medium to perform development; a transport magnet roller for transporting the developed developer drawn up by the developing magnet roller; and a transport magnet. A scraper for scraping off the developer magnetically attracted by the roller, the developer being a magnetic pole formed on the transfer magnet roller, the developer being released from the transfer magnet roller. The magnetic poles and the developer carrying magnetic poles formed on the developer carrying passage of the developer releasing magnetic poles are formed such that the spikes of the developer are formed almost continuously between the magnetic poles. And the tip of the scraper is set so that the developer release magnetic pole is closer to the developer carrying magnetic pole. A developing device.