JPH0812518B2 - Developing device for electrophotographic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used in an electrophotographic apparatus such as a copying machine or a laser printer, and is a developing device for developing an electrostatic latent image formed on a photoconductor. It is about.

[Conventional technology]

For example, in an electrophotographic apparatus such as a copying machine, conventionally, the electrostatic latent image is developed by attaching a toner made of a color pigment to the electrostatic latent image formed on the photoconductor to form a visible image. It has become.

In this case, a plurality of developing devices containing toners of various colors are provided inside the copying machine in order to visualize not only the electrostatic latent image in black but also color in each color. There is also a configuration in which the developing device of No. 1 can be selected and used. For example, in the case of forming a full-color image, a developing device accommodating cyan, magenta, yellow, and, if necessary, a black toer is separately provided, and light exposure is performed by color separation through a plurality of predetermined color filters. Thereby forming an electrostatic latent image on the photoconductor. After developing this electrostatic latent image with toner of a color corresponding to each filter, the toners of the respective colors are superposed to obtain a full-color copy image.

As described above, in order to attach only the toner of a specific color among the toners of various colors stored in the plurality of developing devices to the photoconductor, the toner does not attach to the photoconductor in the developing device that is not used for the development. Need to be configured. Therefore, for example, the developing gap, that is, the distance between the photoconductor and the developing unit of the developing device can be changed, and when the developing device is not used for the development, the developing gap is switched to be large so that the toner on the photoconductor is not changed. It does not adhere.

However, as described above, if the developing gap or the like is switched when the developing device is not used for the development, the developing conditions vary, and the image density tends to change in the future. Especially, if the development gap is not positioned accurately,
It becomes impossible to always form a normal image.

Further, in the developing device adopting the magnetic brush developing method, the position of the magnetic pole of the magnet constituting the developing section is shifted during non-developing so that the magnetic brush formed in the vicinity of the magnetic pole and the photoconductor are brought into contact with each other. However, in this type of developing device, especially when a two-component developer is used, if the magnetic poles are not positioned accurately, the change in image density In addition to the above, the carrier adheres to the recording medium, resulting in a marked deterioration in image quality.

Therefore, a blocking plate is provided in the path of the developer reaching the developing unit where the magnetic brush is formed, and by opening and closing the blocking plate, the supply of the developer to the developing unit is controlled and the developing device is used for the development. Some have been made to be able to switch whether or not to be performed.

By the way, in the developing unit of the developing device using the magnetic brush developing method as described above, a magnet roller provided with a sleeve rotatably fitted to the outer periphery of a cylindrical magnet is usually used as a photosensitive member on which an electrostatic latent image is formed. Are provided so as to face each other.

Further, a sleeve that rotatably fits around the outer circumference of the cylindrical magnet is provided so that the developer circulates smoothly inside the developing device, and the sleeve is arranged close to the developing magnet roller to develop the electrostatic latent image. There is also provided one in which a conveying roller that receives and conveys the developer after being supplied to the developing roller is provided, and a separator that partitions the conveying roller and the developing magnet roller.

The separator is provided so that the gap between the developing magnet roller and the sleeve is as narrow as possible,
By scraping off the developer attached to the surface of the sleeve of the magnet roller for development, which has been used for development,
The developer was reliably delivered to the transport magnet roller.

[Problems to be Solved by the Invention]

However, in the developing device of the above-mentioned conventional electrophotographic apparatus,
When the developer is transferred from the developing magnet roller to the conveying magnet roller, a pressure is generated due to a change in the moving direction of the developer. Due to this pressure, the developer existing near the area surrounded by the developing magnet roller, the conveying magnet roller, and the separator tends to be excessively stressed, which causes the deterioration of the developer. Was there.

[Means for solving the problem]

In order to solve the above problems, a developing device of an electrophotographic apparatus according to the present invention includes a rotatable magnet sleeve, and a developing magnet roller that conveys a developer in opposite directions, and the developing magnet roller. And a transport magnet roller for delivering and transporting the developer after being used for the development of the electrostatic latent image from the developer and the transport magnet roller are arranged close to each other, and the developing magnet roller and the transport magnet roller are In the developing device of the electrophotographic apparatus, which is provided with a separator for partitioning the space between the facing center of these rollers on the front side in the transport direction of the developing magnet roller, the gap between the sleeve of the developing magnet roller and the separator is On the surface of the developing magnet roller due to the developer not transferred from the developing magnet roller to the conveying magnet roller. It is characterized in that it is set to be greater than the thickness of the developer layer is made.

[Action]

With the above structure, the gap between the sleeve of the developing magnet roller and the separator is formed on the surface of the sleeve of the developing magnet roller by the developer not transferred from the developing magnet roller to the conveying magnet roller. Since the thickness is set to be larger than the thickness of the developer layer, when the developer is transferred from the developing magnet roller to the conveying magnet roller, the pressure generated due to the change in the moving direction of the developer is ,
The space between the sleeve of the developing magnet roller and the separator is allowed to escape.

Therefore, it is possible to prevent an excessive stress from being applied to the developer existing near the region surrounded by the developing magnet roller, the conveying magnet roller, and the separator.

〔Example〕

As an embodiment of the present invention, the case of use in a copying machine will be described below with reference to FIGS. 1 to 5.

Inside the copying machine, for example, as shown in FIG. 2, a pair of drive rollers 1 and 2 are provided.
An endless belt-shaped photoconductor 3 on which an electrostatic latent image is formed by being exposed is stretched between the two. A plurality of developing tanks 4 are disposed above the photoconductor 3 so as to face the photoconductor 3 and can be switched between a developing position and a non-developing position.
~ 7 are provided. Replenishing tanks 20 for accommodating toner are arranged above the developing tanks 4 to 7. A cleaning blade 16 is provided below the photoconductor 3.

In the vicinity of the drive roller 1, there are three rollers 8, 9, ...
10 are provided, and an endless belt-shaped intermediate transfer member 11 that comes into contact with the photoconductor 3 is provided on these rollers 8, 9, 10. A main charger 12 is provided near the driving roller 2, and a first transfer charger 13 is provided near the roller 8.
And a second transfer charger 15 is provided below the roller 10.

A paper feeding device 17 for supplying the transfer paper 14 is provided on one side of the lower part of the copying machine, while the transfer paper is provided on the other side.
A fixing device 18 for fixing the toner transferred to 14 is provided. An exposure device 19 for exposing the photoconductor 3 to form an electrostatic latent image is provided above the copying machine.

All of the developing tanks 4 to 7 have the same structure, and for example, as shown in FIG. 1 for the developing tank 4, a sleeve 22b rotatably fitted to the outer circumference of a cylindrical magnet 22a is provided.
A developing magnet roller 22 forming a developing unit is provided facing the opening 21 for transferring toner to the photoconductor 3.

The cylindrical magnet 22a is fixed to the developing tank 4. A magnetic pole N11 is formed at a position facing the photoconductor 3 on the outer peripheral portion of the cylindrical magnet 22a, and magnetic poles S11, N12, and S12 are sequentially formed in the direction indicated by arrow A. The sleeve 22b that is rotatably fitted to the cylindrical magnet 22a is made of, for example, a non-magnetic material such as aluminum and has a cylindrical shape.

Like the developing magnet roller 22, a sleeve 23b rotatably fitted around the outer periphery of the cylindrical magnet 23a is provided above the developing magnet roller 22, and the developer after being developed is used as a developing magnet. A transfer magnet roller 23 is provided which is transferred from the roller 22 and is transferred upward.

The columnar magnet 23 a that constitutes the carrying magnet roller 23 is fixed to the developing tank 4. The developing magnet roller 2 on the outer peripheral portion of the cylindrical magnet 23a.
A magnetic pole S21 is formed at a position closest to 2, and
Magnetic poles N21, S22, N22, and S23 are sequentially arranged in the direction indicated by arrow B.
Are formed. Further, the sleeve 23b is made of a non-magnetic material such as aluminum and has a cylindrical shape similarly to the carrying magnet roller 23 of the developing magnet roller 22.

In contrast to the magnetic pole S21 of the columnar magnet 23a that constitutes the transport magnet roller 23 is formed at the position closest to the developing magnet roller 22 as described above,
A cylindrical magnet that constitutes the developing magnet roller 22.
The magnetic pole N12 of 22a is formed at a position displaced in the direction opposite to the direction indicated by arrow A from the position closest to the transport magnet roller 23. Further, the magnetic force of the magnetic pole N12 of the cylindrical magnet 22a forming the developing magnet roller 22 is set to be smaller than the magnetic force of the magnetic pole S21 of the cylindrical magnet 23a forming the conveying magnet roller 23.

Above the carrying magnet roller 23, the developer carried by the carrying magnet roller 23 and the toner replenished from the replenishing tank 20 based on a signal from a toner concentration sensor 28 described later are stirred. A stirring roller 24 is provided. Diagonally below the transport magnet roller 23,
That is, below the first stirring roller 24, the second stirring roller which further stirs the developer stirred by the first stirring roller 24 and supplies it to the developing magnet roller 22.
25 are provided. These agitating rollers 24 and 25 are respectively rotatably supported on the developing tank 4 by the central shafts 30 and 30.
In addition, a plurality of stirring fins 31 ... Is provided in a spiral shape.

As shown in FIG. 3, a boss member 46 is attached to one end of the central shaft 30 of the second stirring roller 25,
A drive gear 54 is attached to the other end of the central shaft 30. A driving force is transmitted from a driving means (not shown) to the driving gear 54, so that the stirring fin 31 and the boss member 46 are rotationally driven.

In addition, as shown in FIG.
A closure device 35 is installed. This occlusion device 35
Flange members 61 and 62 rotatably supported near both ends of the central shaft 30 of the second stirring roller 25, respectively, and a closing plate mounted between these flange members 61 and 62 and having an arc-shaped cross section. It consists of 38 and 38. The closing plates 38, 38 are arranged in point-symmetrical positions with respect to the central axis 30 of the second stirring roller 25, and have slit-shaped openings 63,
63 is formed.

On the outer side of the flange member 62 in the closing device 35, a shaft portion 62a protruding outside the developing tank 4 is formed. A cylindrical clutch cover 40 is loosely fitted around the shaft portion 62a and the outer periphery of the boss member 46 attached to the central shaft 30 of the second stirring roller 25. Clutch cover 40
A notch 40a is formed at one end of the coil spring 47, and one end of the coil spring 47 is fixed.

A flange member is provided on the other end of the coil spring 47.
It is fixed to the shaft portion 62a of 62. The coil spring 47 is set so that the inner diameter when no external force is applied is smaller than the outer diameters of the shaft portion 62a of the flange member 62 and the boss member 46. Further, the spiral direction of the coil spring 47 is changed by the rotational force in a predetermined direction transmitted from the driving means to the boss member 46.
However, the inner diameter is set so as to shrink so as to further tighten the boss member 46 and the shaft portion 62a of the flange member 62.

That is, according to the operation of the switching means 36 described later,
When the clutch cover 40 can rotate integrally with the boss member 46, since the boss member 46 and the shaft portion 62a of the flange member 62 are tightened by the coil spring 47, the rotational force transmitted from the central shaft 30 to the boss member 46. But in addition,
While being transmitted to the flange member 62 via the coil spring 47 and the shaft portion 62a, when the rotation of the clutch cover 40 is restricted, a portion of the coil spring 47 located near the outer periphery of the boss member 46 is Since the tightening force of the boss member 46 by 47 is loose,
A slip is generated between the coil spring 47 and the coil spring 47, so that the transmission of the driving force from the boss member 46 to the flange member 62 is blocked.

On the outer periphery of the clutch cover 40 of the spring clutch 39, as shown in FIG. 5, claws 40b to 40e are provided in four equally divided portions, that is, at every 90 ° center angle. Further, in the vicinity of the claws 40b to 40e on the outer periphery of the clutch cover 40,
The two protrusions 40f and 40g are formed in positions symmetrical with respect to the central axis 30 of the second stirring roller 25.

The shaft portion 62a of the flange member 62, the boss member 46, the coil spring 47, and the clutch cover 40 constitute a spring clutch 39.

On the outside of the developing tank 4 on the side where the spring clutch 39 is provided, there is further provided a switching means 36 for controlling the transmission and interruption of the driving force by the spring clutch 39 to switch the open / close state of the closing device 35. There is. A stopper portion 49 is formed on one end side of the switching means 36, and the stopper portion 49 is used for the pawls 40b to 40e of the clutch cover 40.
Arm that engages with and prevents rotation of the clutch cover 40
43, a support shaft 48 for rotatably supporting the central portion of the arm 43, a solenoid body 44a and a plunger 44b,
The stopper portion 49 of the arm 43 and the claw 40 of the clutch cover 40
The solenoid 44 for rotating the arm 43 in the direction to release the engagement with b to 40e, is interposed between the arm 43 and the solenoid main body 44a of the solenoid 44, and is provided between the stopper portion 49 of the arm 43 and the clutch cover 40. A spring 45 for urging the arm 43 in a direction to engage the claws 40b to 40e, and a clutch cover.
The projecting pieces 40f and 40g of 40 are provided with a rotary position detection switch 53 that detects an open / closed state of the closing device 35 by being turned on when a movable piece (not shown) is pressed.

A separator 29 is provided between the developing magnet roller 22, the conveying magnet roller 23, the first stirring roller 24, and the second stirring roller 25 to partition these rollers from each other. The gap d between the separator 29 and the sleeve 22b of the developing magnet roller 22 is developed by the developer not transferred from the developing magnet roller 22 to the conveying magnet roller 23.
It is set to be larger than the thickness of the developer layer formed on the surface of the sleeve 22b.

Transport magnet roller on top of separator 29
The end on the 23 side is formed in an acute angle shape, and scrapes off the developer carried by the carrying magnet roller 23 from the sleeve 23b. Further, the upper surface of the separator 29 is formed as an inclined surface descending from the acute-angled end portion on the side of the conveying magnet roller 23 to the end portion on the side of the second stirring roller 25.

The portions of the separator 29 that face the transport magnet roller 23 and the second stirring roller 25 are respectively
The sleeve 23b of the magnet roller 23 for conveyance, and the second
A closing plate 38 of a closing device 35 provided on the outer circumference of the stirring roller 25
The circular arc surface 32.
33 are formed. On the other hand, the portion of the wall surface of the developing tank 4 facing the second agitating roller 25 is similarly closed by the closing device 35.
It is formed in an arc shape so that the gap between it and the closing plate 38 can be kept small.

Since the separator 29 and the wall surface of the developing tank 4 are formed as described above, the developer passage is formed between the first stirring roller 24 and the second stirring roller 25 by the wall surface of the developing tank 4 and the separator 29. While the 64 is formed, a developer passage 65 is formed between the second stirring roller 25 and the developing magnet roller 22. Also, the developer passages 64 and 65
Is connected or closed with the rotation of the closing device 35,
By controlling the supply of the developer to the developing magnet roller 22, the developing tank 4 can be switched between the developing state and the non-developing state.

A toner concentration sensor 28 that detects the concentration of toner contained in the developer is provided below the developer passage 65. Further, below the toner concentration sensor 28 in the developer passage 65, a doctor 27 that forms a predetermined gap with the sleeve 22b of the developing magnet roller 22 is provided.

In the above configuration, turn on the copy switch (not shown)
By the operation, the drive rollers 1 and 2 are respectively indicated by arrows C and D.
It rotates at a constant speed in the direction indicated by. Therefore, the portion of the photoconductor 3 on the upper side of the drive rollers 1 and 2 moves in the direction indicated by the arrow E, is uniformly charged by the main charger 12, and then is exposed by the exposure device 19 to form an electrostatic latent image. Is formed. This electrostatic latent image is developed by toner adhesion by the developing tank in the developing tanks 4 to 7.

The developed toner image moves in the direction indicated by arrow E as the photosensitive member 3 moves, and is transferred to the intermediate transfer member 11 by the first transfer charger 13. The toner image transferred to the intermediate transfer member 11 is further fed by the second transfer charger 15 to the paper feeding device 17 ...
The image is transferred onto a transfer paper 14 sent from and is fixed by a fixing device 18.

As described above, when the electrostatic latent image formed on the photoconductor 3 is developed by the developing tanks 4 to 7, the following operations are performed inside the developing tanks 4 to 7.

In the first stirring roller 24, the toner supplied from the replenishing tank 20 and the developer carried by the carrying magnet roller 23 are agitated and mixed. Here, when the developing tank is in the developing state, the closing device 35 attached to the second agitating roller 25 is rotated so that the slit-shaped openings 63, 63 face the developer passage 64 and the developer passage 65. Is set to. Therefore, the developer stirred by the first stirring roller 24 passes through the developer passage 64, reaches the second stirring row 25, and is further stirred by the second stirring roller 25.
It is supplied to the developing magnet roller 22 through the developer passage 65.

When the developer passes through the developer passage 65, the toner concentration sensor 28 detects the concentration of the toner contained in the developer. When the concentration of the toner contained in the developer becomes equal to or lower than a predetermined concentration, new toner is supplied from the replenishment tank 20.

The developer in the developer path 65 is the developing magnet roller 22.
Due to the gap formed between the sleeve 22b and the doctor 27, the amount of the developer adhering to the sleeve 22b is regulated to be appropriate. The developer attached to the sleeve 22b is
With the rotation of the sleeve 22b in the direction indicated by the arrow A, the sleeve 22b moves downward and reaches the vicinity of the lower side of the magnetic pole N11 formed on the cylindrical magnet 22a of the developing magnet roller 22.

In the vicinity of the lower part of the magnetic pole N11, the developer becomes a brush according to the direction of the magnetic force lines, and so-called spikes are formed.
When the spikes are brought into sliding contact with the photoconductor 3, the photoconductor 3
The toner adheres only to the charged portion where the electric charge is present, and the electrostatic latent image is developed.

The developer after being subjected to development rises as the sleeve 22b rotates while adhering to the sleeve 22b, and reaches the vicinity of the lower portion of the transport magnet roller 23. In the vicinity of the lower portion of the transport magnet roller 23, first, a bristles are formed according to the direction of the magnetic force lines of the magnetic pole N12 formed on the cylindrical magnet 22a of the developing magnet roller 22. Then, when the sleeve 22b further rotates, the influence of the magnetic line of force of the magnetic pole S21 formed on the cylindrical magnet 23a of the transport magnet roller 23 strongly affects the developer.

Therefore, in particular, since the magnetic force of the magnetic pole S21 of the cylindrical magnet 23a is set to be stronger than the magnetic force of the magnetic pole N12 of the cylindrical magnet 22a, the developing magnet roller is used.
Most of the developer adhering to the sleeve 22b of 22 is absorbed by the spikes formed on the surface of the sleeve 22b of the conveying magnet roller 23 due to the influence of the magnetic pole S21 of the cylindrical magnet 23a, and the arrow of the sleeve 23b is shown. It is conveyed upward with the rotation in the direction indicated by B.

At this time, in the vicinity of the area surrounded by the developing magnet roller 22, the conveying magnet roller 23, and the separator 29, the direction in which the developer flows changes. But,
Sleeve 22b of developing magnet roller 22 and separator 2
The gap d with respect to 9 is larger than the thickness of the developer layer formed on the surface of the sleeve 22b of the developing magnet roller 22 by the developer not transferred from the developing magnet roller 22 to the conveying magnet roller 23. Since the pressure of the developer escapes from this gap, the pressure of the developer does not become too high.

Therefore, as the sleeve 22b of the developing magnet roller 22 rotates, the developer transported to the position of the pole N12 formed on the cylindrical magnet 22a is efficiently transferred to the sleeve 22b of the transporting magnet roller 23. In addition, the developer can be smoothly conveyed and circulated without applying excessive stress to the developer.

Therefore, the deterioration of the developer due to the excessive stress applied to the developer in the carrying stage can be significantly suppressed.

On the other hand, the developer adhered to the sleeve 23b of the carrying magnet roller 23 is carried further upward as the sleeve 23b rotates in the direction shown by the arrow B, and an acute angle on the carrying magnet roller 23 side above the separator 29. Scraped at the edges. The developer scraped off by the separator 29 moves downward along the inclined surface forming the upper surface of the separator 29, and as described above, is supplied by the first stirring roller 24 to the replenishment tank 20.
It is mixed and stirred with the toner supplied from. After that, the circulation of the developer is repeated as the rollers 22 to 25 rotate, and the electrostatic latent image formed on the photoconductor 3 is developed.

When the development of the electrostatic latent image formed on the photoconductor 3 is completed as described above, the non-developed state, that is, the toner is on the photoconductor, is ready for development by another developing tank. It is necessary to make it a state where it does not adhere to 3. Therefore,
The switching unit 36 performs the following closing operation on the closing device 35.

First, the solenoid 44 is energized and the plunger 44
b drives backwards against the biasing force of the spring 45. Therefore, the arm 43 rotates in the direction indicated by the arrow P, and the arm 43
The engagement between the stopper portion 49 of the spring clutch 39 and the claw 40b of the clutch cover 40 in the spring clutch 39 is released, and the clutch cover 40 rotates integrally with the boss member 46 attached to the central shaft 30 of the second stirring roller 25. I will get it.

Then, due to the rotational force of the boss member 46 and the clutch cover 40, the inner diameter of the coil spring 47 tries to contract, and the boss member 46 and the shaft portion 62a formed on the flange member 62 of the closing device 35 are tightened. So the central axis 3
The rotational force transmitted from 0 to the boss member 46 is further transferred to the flange member 6 via the coil spring 47 and the shaft portion 62a.
2, and the closing device 35 is rotated.

On the other hand, the energization of the solenoid 44 is stopped after the clutch cover 40 starts to rotate, and the arm 43 rotates in the direction indicated by the arrow Q by the urging force of the spring 45. Therefore,
When the clutch cover 40 rotates about 90 ° as described above,
This time, the claw 40c of the clutch cover 40 engages with the stopper portion 49 of the arm 43, and the rotation of the clutch cover 40 is restricted again.

Therefore, the boss member 46 of the coil spring 47 is
Since the tightening force of the boss member 46 by the coil spring 47 is relaxed in the portion located near the outer periphery of the, the driving force is not transmitted from the boss member 46 to the flange member 62, and the rotation of the closing device 35 is stopped. That is, the closing device 35 stops together with the clutch cover 40 at a position rotated by about 90 °, and the developer passage
64 and 65 are closed by the closing plates 38 and 38 of the closing device 35.

Therefore, the developer agitated by the first agitating roller 24 is prevented from reaching the developing magnet roller 22, and the developer adsorbed on the developing magnet roller 22 is eventually absorbed by the carrying magnet roller 23. After all have been conveyed, the rollers 22 to 25 are stopped. therefore,
Cylindrical magnet 22a in developing magnet roller 22
The ears of the developer formed near the lower part of the magnetic pole N11 formed in the above are disappeared, and the development of the photoconductor 3 by the toner in the developing tank is stopped until the next development is performed. It will be in a standby state.

In addition, as described above, the blocking device 35 causes the developer passages 64 and 65 to pass.
When it is in the closed state, the movable piece of the rotation position detection switch 53 is not pressed by any of the protrusions 40f and 40g formed on the clutch cover 40, and the rotation position detection switch 53 is turned off. Therefore, the control device (not shown) detects that the developing device is not in the developing state.

On the other hand, when the development of the photoconductor 3 is started again by the developing tank in the standby state as described above, the solenoid 44 is energized and the spring clutch 39 is turned on as in the case where the development is completed as described above. Through the occlusion plate 38 or about
Rotate 90 °. The developer passages 64 and 65 are closed by the blocking device 35.
The developer is supplied to the developing magnet roller 22 again by communicating with each other through the slit-shaped openings 63, 63, the spikes of the developer are formed, and the development of the photoconductor 3 is performed. Done.

As described above, by providing the conveying magnet roller 23 above the developing magnet roller 22, the developing tank 4
It becomes possible to smoothly circulate the developer while reducing the size of the developing tanks 7 to 7 in the width direction and downsizing the developing tanks 4 to 7. In particular, the magnetic force of the magnetic pole S21 formed on the cylindrical magnet 23a of the carrying magnet roller 23 is the magnetic pole N formed on the cylindrical magnet 22a of the developing magnet roller 22.
Since the magnetic force is set to be larger than the magnetic force of 12, the developer conveyed by the developing magnet roller 22 is efficiently transferred to the conveying magnet roller 23.

Moreover, when the developer is transferred from the developing magnet roller 22 to the conveying magnet roller 23, the pressure generated by the change in the moving direction of the developer is the sleeve 22b of the developing magnet roller 22 and the separator 2
Since it escapes from between 9 and 9, excessive stress is not applied to the developer existing near the area surrounded by the developing magnet roller 22, the conveying magnet roller 23, and the separator 29, and the deterioration of the developer is ensured. To be prevented.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, although the developing magnet roller 22 and the conveying magnet roller 23 are arranged in the vertical direction in the above-mentioned embodiment, the present invention is applicable not only to this but also in the case of arranging them in the horizontal direction.

Further, the number and arrangement order of the magnetic poles formed on the cylindrical magnets 22a and 22b are not limited to those in the above embodiment. Further, the photoconductor 3 is not limited to the belt-shaped one as in the above embodiment, but may be a drum-shaped one. Further, the number of developing tanks is not limited to plural, and one developing tank may be applied. The rotation stop position of the closing device 35 is set by setting the width of the closing plates 38, 38 of the closing device 5 in the above embodiment to be larger than the distance between the wall surfaces of the developing tanks 4 to 7 and the separator 29. Magnet roller 22 for development due to variations in
The developer may be configured to be surely prevented from flowing out.

〔The invention's effect〕

As described above, the developing device of the electrophotographic apparatus according to the present invention includes the developing magnet roller that includes the rotatable sleeves and conveys the developer in the opposite directions, and the electrostatic latent image from the developing magnet roller. A transport magnet roller that delivers and transports the developer after being used for image development is disposed close to each other, and between the developing magnet roller and the transport magnet roller,
In a developing device of an electrophotographic apparatus, which is provided with a separator which is located on the front side in the conveying direction of the developing magnet roller from the facing center of these rollers, the gap between the sleeve of the developing magnet roller and the separator is the developing magnet. The thickness of the developer layer formed on the surface of the developing magnet roller is larger than the thickness of the developer layer that has not been transferred from the roller to the conveying magnet roller.

As a result, when the developer is transferred from the developing magnet roller to the conveying magnet roller, the pressure generated by the change in the moving direction of the developer is generated between the sleeve of the developing magnet roller and the separator. Since it can be released, excessive stress is not applied to the developer existing near the region surrounded by the developing magnet roller, the conveying magnet roller, and the separator.

Therefore, there is an effect that the deterioration of the developer can be easily prevented.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a vertical sectional view showing the structure of a developing tank, and FIG. 2 is a vertical sectional view showing the structure of a copying machine. FIG. 3 is a vertical cross-sectional view showing the configurations of the second stirring roller and the spring clutch,
FIG. 4 is a perspective view showing the structure of the second stirring roller, and FIG. 5 is a front view showing the structure of the switching means of the closing device. 3 is a photoconductor, 4 to 7 is a developing tank, 22 is a developing magnet roller, 22a is a cylindrical magnet, 22b is a sleeve, 23 is a conveying magnet roller, 23a is a cylindrical magnet, 23b is a sleeve, and 29 is a separator. is there.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-208077 (JP, A) JP 60-50563 (JP, A) Actually opened 55-47009 (JP, U)

Claims (1)

[Claims] 1. A developing magnet roller, each of which has a rotatable sleeve and conveys the developing agent in opposite directions, and a developing agent which has been used for developing an electrostatic latent image from the developing magnet roller. The transfer magnet roller to be transferred and transferred is disposed close to each other, and the transfer magnet roller is transferred between the developing magnet roller and the transfer magnet roller from the center of opposition of these rollers. In a developing device of an electrophotographic apparatus provided with a separator for partitioning on the front side in the direction, the gap between the sleeve of the developing magnet roller and the separator is not transferred from the developing magnet roller to the conveying magnet roller. It is set to be larger than the thickness of the developer layer formed on the surface of the developing magnet roller by the agent. A developing device for an electrophotographic apparatus, which is characterized in that