JPH11311901A - Developing device and image forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the flocculation of developer in a developing device in which the napping height of the developer is regulated by forming a wall surface opposed to a sleeve nearly along the ridge line of a magnetic brush on the upstream side of a regulating member in a developer carrying direction. SOLUTION: A carrying amount regulating member 60 has a regulation projecting part 61 opposed to the surface of the sleeve 31a through fixed space over its longitudinal direction and is formed of aluminum. The developer is gradually regulated from the front part of the projecting part 61, and finally passes therethrough by an amount regulated by the space. A flow rate regulating member 90 formed of aluminum is provided adjacently to the member 60. The member 90 has the same length as the member 60, and the wall surface 91 opposed to the sleeve 31a of a developer carrying roller 31 is formed nearly along the ridge line of the magnetic brush formed on the sleeve 31a. Therefore, the developer near the wall surface 91 is sufficiently attracted by the magnetic force of a magnet roll 31c, so that the developer is smoothly carried without being retained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device employing a two-component magnetic brush developing system and an image forming apparatus such as a copying machine or a printer using the developing device.

[0002]

2. Description of the Related Art In a developing apparatus using a two-component developer composed of a toner and a magnetic carrier, the carrier and the toner are frictionally charged by stirring the developer. The toner electrostatically adheres to the carrier surface due to the triboelectric charging, and the carrier to which the toner adheres is supplied to the transport roller.

A bucket roller is known to efficiently perform both the stirring of the developer and the supply of the developer to the transport roller. FIG. 5 shows a part of the developing device provided with the bucket roller. This bucket roller 220
A plurality of trough-shaped buckets 260 are provided between two disk-shaped side plates provided opposite to each other at a predetermined interval on the rotating shaft, and recesses are formed at predetermined intervals in the circumferential direction of the side plates. Are arranged so as to face outward, and a plurality of stirring blades 270 are provided between the buckets.

The above-structured bucket roller 220 is
A predetermined gap is provided with the bottom of a developer container having a U-shaped cross section provided therebelow, and the developer is stored in the developing container so that substantially the lower half of the bucket roller 220 is buried. I have. When the bucket roller 220 is rotated at a relatively high speed in the direction of the arrow, the developer
After being pumped at 0 and scraped off by the sliding member 800, it is supplied to the transport roller 310. Further, the developer in the developing container is stirred by the stirring blade 270.

The transport roller 310 is composed of a fixed magnet roll 310c having a plurality of magnetic poles in the circumferential direction and a sleeve 310a enclosing the magnet roll 310c. The developer supplied by the bucket roller 220 deposits the developer on the sleeve surface. Magnetically attracted. The magnetically attracted and brush-shaped developer is conveyed by the rotation of the developing sleeve, the conveyance amount is regulated by the spike height regulating member 600, and further conveyed.

[0006]

The developer regulated (pushed back) by the spike height regulating member 600 stays at a corner or the like as shown by an arrow A in the figure. In such a state, for example, when the temperature in the copying machine, that is, the temperature in the developing device rises as in a case where copying is continuously performed, the accumulated developer aggregates. When the agglomerated developer is used for development, a problem occurs that noise is generated in a finished image.

Although the developing device using a bucket roller has been described above as an example, any developing device that employs a system in which the amount of developer conveyed on the sleeve is regulated by a spike height regulating member may be used. May occur in a space in front of the ear height regulating member. SUMMARY OF THE INVENTION In view of the above-described problems, the present invention provides a developing device that controls the height of a developer conveyed on a sleeve, in which the aggregation of the developer is prevented, and an image forming apparatus using the developing device. With the goal.

[0008]

In order to achieve the above object, a developing device according to the present invention comprises a fixed magnet body having a plurality of magnetic poles on a peripheral surface thereof, and is rotated in one direction by rotating the fixed magnet body. A sleeve that receives a developer containing magnetic particles at a predetermined receiving position in cooperation with a magnet body, forms a magnetic brush, and conveys the sleeve; and a regulating member that regulates an amount of the developer conveyed on the sleeve. Wherein a wall surface facing the sleeve is formed substantially along a ridge line of the magnetic brush on the upstream side of the regulating member in the developer transport direction.

Further, the developing device further has a developer accommodating portion for accommodating a developer, and a plurality of buckets in a circumferential direction. A bucket roller for pumping up the developer and transporting the developer to the receiving position of the sleeve; and for the developer on the bucket being pumped to scrape off the developer on the bucket before reaching the developer receiving position of the sleeve. And a sliding member made of a magnet.

Further, an image forming apparatus according to the present invention includes the above-mentioned developing device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to a single-color digital copying machine (hereinafter simply referred to as "copier").
An example in which the present invention is applied will be described. FIG. 1 is a diagram illustrating an entire configuration of a copying machine according to an embodiment. The copying machine includes an image reader unit 1 for reading a document image and a printer unit 2 for printing the read image on copy paper and reproducing the image.
It is composed of

The image reader section 1 is a well-known one that scans an original image placed on a platen glass and converts the scanned image into an electric signal to obtain image data. The image data obtained by the image reader unit 1
The digital signal is subjected to / D conversion and further subjected to necessary processing such as shading correction, density conversion, and edge enhancement, and then output as a laser diode drive signal.

The printer unit 2 forms an image on copy paper by an electrophotographic method, and includes an exposure scanning unit 4, an image processing unit 5, a paper feeding unit 6, and the like. The exposure scanning unit 4 includes a laser diode 7, a polygon mirror 8, a scanning lens 9, and the like. The laser diode 7 receives the drive signal from the control unit 3 and emits light modulated laser light. The emitted laser light is reflected and deflected by a mirror surface of a polygon mirror 8 that is driven to rotate at a constant speed, passes through a scanning lens 9, and exposes and scans the surface of the photosensitive drum 10 of the image processing unit 5.

The image processing unit 5 includes the photosensitive drum 1
0, a cleaner 11, an eraser lamp 12, a charging charger 13, a developing device 14, and the like are arranged. The photoreceptor drum 10 is uniformly charged by a charging charger 13 after the residual toner on the photoreceptor surface is removed by a cleaner 11 before receiving the above-mentioned exposure, and further irradiated by an eraser lamp 12 to remove electricity. When exposure is performed in such a uniformly charged state, an electrostatic latent image is formed on the photoconductor on the surface of the photoconductor drum 10.

The electrostatic latent image is developed by the developing device 14 and is visualized as a toner image. This toner image is
The transport belt 1 is fed from the sheet feeding unit 6 in synchronization with the image forming operation and stretched by a driving roller 18 and a driven roller 19.
7, the image is transferred onto the copy paper conveyed by
Then, the paper is discharged onto the paper discharge tray 16 and the image formation based on the image data of the document is completed.

FIG. 2 is a sectional view of the developing device 14. The developing device 14 mainly includes a developer supply unit 20 and a developing unit 3.
0, a toner density detecting section 40 and a toner replenishing section 50. The developer supply section 20 includes a developer tank 21 and a bucket roller 22. The developer tank 21 has a groove-shaped bottom having a semicircular cross section having a longitudinal direction perpendicular to the paper surface, and stores a two-component developer composed of a toner and a magnetic carrier in the groove-shaped recess.

The bucket roller 22 is provided so that its outermost periphery has a certain gap with the groove-like bottom of the developer tank 21. The bucket roller 22 is provided with two
The side plates 24 and 25 are attached to face each other (only the side plate 24 on the back side of the drawing is shown in the drawing).
A plurality of buckets 26 (six in the illustrated example) are erected between 25. The bucket 26 has a gutter shape having a substantially U-shaped cross section, and is attached to the side plates 24 and 25 at substantially intervals such as in the circumferential direction of the same circle so that the concave portions thereof face outward. Since each bucket 26 is provided at a predetermined interval as described above, each bucket 2
The developer can flow into and out of the bucket roller 22 through the space between the six rollers. Also, the bucket roller 22
Has a plurality of stirring blades 27 and 28 for stirring the developer, respectively. The stirring blades 27 and 28 are thin plate-shaped members provided at a predetermined angle with respect to the axial direction of the rotating shaft 23, one of which is fixed to the plurality of buckets 26, and It is attached at a predetermined interval. Further, the stirring blades 27 and 28 are connected to the side plate 2.
It has a role of transporting the developer in the two directions of the side plates 24 and 25 from substantially the center between the side plates 4 and 25. Therefore, the stirring blades 27 and 28 with respect to the rotation shaft 23 are separated from the substantially center. It is mounted so that the direction of inclination is reversed.

The bucket roller 2 configured as described above
2, when the rotating shaft 23 is rotated at a relatively high speed in the direction of arrow a in the figure by a driving means (not shown), the entire bucket roller 22 rotates, and the stirring blades 27 and 28 and the bucket 26 The developer inside is stirred, whereby the toner and the magnetic carrier are frictionally charged.
At the same time, the developer in the developer tank 21 is pumped up by the bucket 26 and supplied to the developing unit 30. Further, the developer is supplied to the side plates 24 and 25 by the stirring blades 27 and 28.
The sheet is conveyed from substantially the center between the side plates 24 and 25 in two directions.

The developing section 30 includes three developer conveying rollers 3
1, 32, 33 and a scraper 34 are provided. The developer transport roller 31 receives the developer supplied by the bucket roller 22, and transports the developer to the next developer transport roller 32. It is provided so as to have a predetermined gap in parallel. Developer transport roller 31
Are a thin cylindrical sleeve 31a and a sleeve 31
a, and a sleeve 31a is formed around a magnet roll 31c, which is fixed so as not to rotate, by a sleeve 31a.
Is configured to rotate in the direction of.

The magnet roll 31c is composed of five pole asymmetric magnetic poles as shown in the figure. The S1 pole is a magnetic pole (hereinafter, a magnet roll 31c) for receiving the developer supplied by the bucket roller 22.
Is also referred to as a "developer receiving magnetic pole". )
Since the developer conveyed with the rotation of the bucket roller 22 is received and received, the rotation direction of the bucket roller 22 is slightly opposite to the position closest to the outer periphery of the bucket roller 22 in the circumferential direction of the magnet roll 31c. It is staggered. The N2 pole is a magnetic pole for delivering the developer to the developer transport roller 32, and is positioned slightly closer to the outer periphery of the developer transport roller 32 in the circumferential direction of the magnet roll 31c. Is provided. A magnetic pole is disposed between the S1 pole and the N2 pole so that the developer is smoothly transported.
Pole and S2 pole (hereinafter referred to as sleeve 3).
The N1 pole adjacent to the developer receiving magnetic pole (S1) on the downstream side in the rotation direction of 1a is also referred to as a "first transport magnetic pole". ). N3
The pole forms an area where the magnetic field is weak between the N2 pole and the N2 pole, releases the developer from the sleeve 31a,
This is a magnetic pole for facilitating the transition to. In the developer transport roller 31 configured as described above, the developer is raised on the surface of the sleeve 31a by the magnetic force of the magnet roll 31c to form a magnetic brush. Sleeve 3
When 1a is rotated, the developer rolls fall down by the magnetic poles of the magnet roll 31c, and the developer is transported in the direction of arrow b, that is, the same direction as the rotation direction of the sleeve 31a. The magnitude of the magnetic force of each magnetic pole is determined by the required amount of the developer to be conveyed. In this example, the S1 pole is set to 500 [G] and the N1 pole is set to 400 [G]. I have. That is, the magnetic force of the developer receiving magnetic pole (S1) is set to be stronger than that of the first transport magnetic pole (N1).

A transport amount regulating member 60 for regulating the thickness of the developer transported on the sleeve 31a, that is, the transport amount between the N1 pole and the S2 pole of the magnet roll 31c is provided. The conveyance amount regulating member 60 is a sleeve 31a.
And a convex portion 61 (hereinafter, this convex portion is referred to as a regulating convex portion 61) which is opposed to the surface of the substrate with a certain gap in the longitudinal direction thereof, and is formed of aluminum. The developer is gradually regulated from a portion in front of the regulating protrusion 61, and finally,
Only the amount defined by the gap passes.

The developer that has passed through the regulating protrusion 61 is transported to the developer transport roller 32 by the rotation of the sleeve 31a. The developer transport roller 32 further transports the developer to the developer transport roller 33. While the developer is transported by the developer transport rollers 32 and 33, the photosensitive drum 1 provided to face the transport rollers 32 and 33.
Develop the latent image on zero.

The toner supply roller 53 of the toner supply section 50
Has a configuration in which a sponge roller 55 is attached to a rotating shaft 54, and the surface (uneven surface) of the sponge roller 55
To capture the toner and use the elastic force of the sponge,
The toner is supplied by rotating while being in close contact with the opening 56. The toner replenished by the toner replenishing roller 53 is linearly poured down onto the rotating bucket roller 22 from above and between the side plates 24 and 25.

Therefore, a part of the supplied toner is
It falls into the bucket roller 22 through the space between the buckets 26 (between the stirring blades 27 or 28), reaches the developer tank 21, and is agitated with the magnetic carrier.
Will be deposited on the developer pumped up in the step. Therefore, it is necessary to wipe off the developer on the bucket 26 and drop the replenished toner into the bucket roller 22 before reaching the developing unit 30. This is to prevent the toner having an insufficient charge amount from being supplied to the developing unit 30 (developer conveying roller 31) due to insufficient stirring with the magnetic carrier. Further, although the developer is pumped up in a heap in the bucket 26, there is also a purpose of stabilizing the supply amount to the developer conveying roller 31 by sliding the developer.

In order to perform this sliding cutting, the developer receiving position of the developer conveying roller 31 from the toner replenishing position by the toner replenishing roller 53 in the rotation direction of the bucket roller 22 (the position facing the magnetic pole S1 of the magnet roll 31c).
, A sliding member 80 is provided. Less than,
Referring to FIG. 3, which is an enlarged view of the vicinity of the sliding member 80, the sliding member 80 is formed of an elongated rectangular bar-shaped magnet,
In parallel with 3, the outermost track of the bucket roller 22 is arranged with a predetermined gap. The sliding member 80 is magnetized in the left-right direction, forms a magnetic brush of a developer (magnetic carrier) on the lower surface side, and slides the developer on the bucket by the magnetic brush. In addition,
The magnitude of the magnetic force of the magnet used for the sliding member 80 is determined by the size of the gap with the bucket roller at the time of installation, but in this example, it is 300 [G] or more and 8
00 [G] or less. In addition, the magnetizing in the left-right direction, instead of the magnetizing in the vertical direction, is performed because the magnetic field is generated in an arc shape on the lower surface side of the sliding-off member 80 so that the developer is cut off. This is for forming the magnetic brush into a suitable shape.

When the sliding member is formed of a magnet as described above, good sliding properties can be obtained, but the developer is more likely to stay in the portion A due to the magnetic force (see FIG. 5). ). Next, the developer transport roller 3
The vicinity of 1 will be further described. Transport amount regulating member 60
A flow path regulating member 90 made of aluminum, which is a non-magnetic material, is provided adjacent to. The flow path regulating member 90 has the same length as the carry amount regulating member 60, and the wall surface 91 of the developer carrying roller 31 facing the sleeve 31 a substantially follows the ridge line of the magnetic brush formed on the sleeve 31 a. It is formed.

FIG. 4 shows a state of the magnetic brush MB formed on the sleeve 31a. As shown in the drawing, the magnetic brush MB has a smooth ridge-like mountain range in which a valley is formed between magnetic poles at a portion corresponding to the magnetic pole due to the magnetic pole pattern of the magnet roll 31c. Tests with the above configuration showed that even when the temperature of the developing device was raised to around 56 ° C., little aggregation of the developer occurred.

Assuming the reason for this, first, as shown in FIG. 2, the magnetic brush and the wall surface 91 of the flow path regulating member 90,
A space R (hereinafter, this space is referred to as a “recirculation path”) having a constant width (length of the ear to be cut) is formed between the developer and the developer pushed back by the conveyance amount regulating member 60. The liquid flows smoothly through the smooth return path R, a part of which falls into the bucket roller 22, and a part is sucked again by the surface of the sleeve 31 a of the conveying roller 31 and is conveyed. It is considered that the agent does not stay in front of the conveyance amount regulating member 60 and aggregation is unlikely to occur.

Second, on the contrary, since the wall surface 91 is substantially in the shape of a ridge line of the magnetic brush formed on the sleeve 31a, the magnetic force of the magnet roll 31c is reduced.
It is considered that the developer in the vicinity can be sufficiently attracted, so that the developer can be smoothly transported without stagnation. Here, since the flow path regulating member is made of non-magnetic aluminum, the developer can be moved smoothly.

In the above-described embodiment, the transport amount regulating member 60 and the flow path regulating member 90 are provided separately, but they may be formed integrally. Furthermore, in the above-described embodiment, the case where the present invention is applied to a developing device in which three developer transport rollers are used has been described as an example.
The present invention is also applicable to a developing device using one, two, or four or more developer conveying rollers. For example, in the case of one developer transport roller, the one developer transport roller is
The developer is arranged so as to face both the bucket roller and the photosensitive drum, and the developer received from the bucket roller is directly conveyed to a developing area which is a position facing the photosensitive drum.

Further, the shape and number of buckets of the bucket roller, the shape and the mounting position of the stirring blade, and the like are not limited to those in the above embodiment. In short, pumping up the developer,
Any configuration that allows stirring and transport in the axial direction is acceptable.

[0032]

As described above, according to the developing device of the present invention, the upstream side of the regulating member that regulates the amount of the developer conveyed as a magnetic brush on the sleeve is located on the upstream side in the developer conveying direction. By forming the wall surface facing the sleeve substantially along the ridge line of the magnetic brush, stagnation does not easily occur, and therefore, aggregation of the developer can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a sectional view of a developing device in the copying machine.

FIG. 3 is a partially enlarged view of the cross-sectional view.

FIG. 4 is a diagram illustrating a state of a magnetic brush of a developer formed on one transport roller of the developing device.

FIG. 5 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 14 Developing Device 21 Developer Tank 22 Bucket Roller 26 Bucket 31 Developer Transport Roller 31a Sleeve 31c Magnet Roll 60 Transport Amount Restriction Member 61 Restriction Protrusion 80 Sliding Member 90 Channel Restriction Member 91 Wall Surface

Claims (3)

[Claims] 1. A developer containing magnetic particles at a predetermined receiving position in cooperation with the magnet body by being covered with a fixed magnet body having a plurality of magnetic poles on a peripheral surface and being rotated in one direction. And a regulating member that regulates the amount of the developer conveyed on the sleeve, and a sleeve that forms and conveys the magnetic brush. A developing device, wherein a wall surface facing the sleeve is formed substantially along a ridge line of the magnetic brush. 2. A developer accommodating section for accommodating a developer, and a plurality of buckets in a circumferential direction, and when the bucket is rotated in one direction, the developer in the developer accommodating section is pumped up by the bucket. A bucket roller for conveying the sleeve to a receiving position, and a sliding cutter comprising a magnet for sliding the developer on the bucket before the developer on the bucket reaches the developer receiving position on the sleeve. The developing device according to claim 1, further comprising a member. 3. An image forming apparatus comprising the developing device according to claim 1.