JPH10333431A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain high image quality over a long term by stably forming a developer layer to be a thin layer without giving excessive stress to two-component developer on a developer carrier. SOLUTION: Plural layer thickness regulating members 6 and 7 are juxtaposed along in the rotating direction of the developer carrier 1 as a layer thickness regulating means 5 regulating the layer thickness of the developer G on the developer carrier 1 and arranged to be opposed to the developer carrier 1; a magnetic body 8 is provided at least at a part of the most downstream layer thickness regulating member 6 positioned on the most downstream side in the rotating direction of the developer carrier 1; and an area between the regulating member 6 and the most upstream layer thickness regulating 7 positioned on the most upstream side in the rotating direction of the developer carrier 1 is arranged to be opposed to the center part of a trimming magnetic pole 4a arrayed on the front side of a developing area (m) out of the magnetic poles 4 of a magnet member 3 fixedly installed in the developer carrier 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in a copying machine such as an electrophotographic system, a printer, and other image forming apparatuses, and more particularly to a developing device using a two-component developer composed of a toner and a carrier. Regarding improvement.

[0002]

2. Description of the Related Art In general, various types of developing devices are used in copying machines, printers and other image forming apparatuses of the electrophotographic type. For example, in a developing apparatus using a two-component developer composed of a toner and a carrier, a developing device is used. A two-component developer is carried on a roll (developer carrier), and the developer is formed into a layer. At the same time, a magnetic brush is used to develop an electrostatic latent image on a latent image carrier such as a photosensitive drum. Generally done. In recent years, there has been a great demand for color and high image quality in copiers and printers, and particularly in development, there has been a demand for faithful development of electrostatic latent images.

In order to faithfully develop an electrostatic latent image, it is necessary to reduce the distance between the latent image carrier and the developer carrier.
Here, as the distance between the latent image carrier and the developer carrier decreases, the developer layer formed on the developer carrier also needs to be formed thinner. Conventionally, as a layer thickness regulating means for regulating the thickness of the developer layer on the developer carrier, one trimming blade (layer thickness regulating member) is used, and the surface of the developer carrier and the trimming blade are usually fixed. A method is adopted in which a gap (trimming gap) is opened and held in a non-contact state. In this method, the developer passing amount can be adjusted by controlling the trimming gap. However, in order to form a thin layer, the trimming gap needs to be set very small.

[0004]

However, when the trimming gap is set to be small, the developer layer formed on the developer carrier becomes uneven or the trimming gap becomes small as compared with the case where the trimming gap is set to be large. A streak is formed in the developer layer due to clogging of a foreign material into a part, and a large stress is applied to the developer when the developer passes through the trimming gap, thereby shortening the life of the developer. There were challenges.

[0005] In order to solve this kind of technical problem, there has been already proposed a method of installing a plurality of layer thickness regulating members as a layer thickness regulating means (for example, Japanese Patent Application Laid-Open No. 58-1051).
76, JP-A-3-160481). For example, of the two layer thickness regulating members, the trimming gap of the upstream layer thickness regulating member located on the upstream side in the rotation direction of the developer carrier is larger than that of the downstream layer thickness regulating member located on the downstream side. A developer that is set to a large value (for example, see Japanese Patent Application Laid-Open No. 3-160481) or a developer that is formed by integrating two layer thickness regulating members and that exists in a region between magnetic poles in a developer carrier (the state of aggregation of the developer) (Where the density is high) is regulated by each layer thickness regulating member (for example, Japanese Unexamined Patent Publication No.
No. -105176) has already been proposed.

Certainly, in this type of system, by providing a plurality of layer thickness regulating members, it is possible to increase the leveling effect of the layer thickness regulating members, and accordingly, a uniform developer layer is provided. May be able to form. However, as shown in the above-described method, simply installing a plurality of layer thickness regulating members cannot increase the trimming gap as compared with the conventional method (using a single layer thickness regulating member). However, it is impossible to reduce the stress on the developer and extend the life of the developer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problem, and stably forms a developer layer without applying excessive stress to a two-component developer on a developer carrier. An object of the present invention is to provide a developing device which can be formed in a thin layer and which can obtain stable and high image quality for a long period of time.

[0008]

That is, according to the present invention, as shown in FIG. 1, an electrostatic latent image Z is developed in a development area m using a two-component developer G comprising at least a magnetic carrier and a toner. In a developing device for forming an image, a rotatable developing sleeve 2 on which a two-component developer G is carried and a plurality of magnetic poles 4 fixedly provided inside the developing sleeve 2 and surrounding the developing sleeve 2
And a layer-thickness regulating means 5 which is arranged opposite to the developer carrier 1 and regulates the layer thickness of the developer G on the developer carrier 1. A plurality of layer thickness regulating members 6 and 7 are provided side by side as the layer thickness regulating means 5 along the rotation direction of the developer carrier 1,
The magnetic material 8 is provided on at least a part of the most downstream layer thickness regulating member 6 located on the most downstream side with respect to the rotation direction of the developer, and the most downstream layer located on the most downstream side with respect to the rotation direction of the developer carrier 1 is provided. The region between the thickness regulating member 6 and the most upstream layer thickness regulating member 7 located on the most upstream side is arranged to face the center of the trimming magnetic pole 4a arranged in front of the developing region m in the magnetic pole 4 of the magnet member 3. It was done.

In such technical means, the magnet member 3 is not necessarily required to be in the form of a roll as long as it is fixed and installed in the developing sleeve 2. From the viewpoint of accurately adjusting the action state of the magnetic field, a roll-shaped member is preferable. The magnetic poles 4 arranged around the magnet member 3 may be formed by appropriately magnetizing the periphery of the metal core, by separately embedding a magnet for the magnetic pole around the core, The magnetic pole sheet may be appropriately selected, for example, by pasting a magnetic pole sheet that has been magnetized at a predetermined par end around the perimeter, and the arrangement pattern of the magnetic poles 4 may be appropriately selected.

The trimming magnetic pole 4a referred to in the present invention is a magnetic pole at a position facing the layer thickness regulating means 5 among the magnetic poles 4 of the magnet member 3 fixed and installed inside the developer carrier 1. It means a magnetic pole that forms a magnetic field that directly acts on the developer G when regulating the layer thickness of the developer G. Further, in the present invention, the central portion of the trimming magnetic pole 4a refers to two distribution points (central points) that measure the radial component of the magnetic flux density of the magnetic pole and show a magnetic flux density of 80% of the maximum magnetic force.
Means

In addition, regarding the structure of the layer thickness regulating members 6 and 7, at least a part of the most downstream layer thickness regulating member 6 has a magnetic material 8.
The lowermost layer thickness regulating member 6 may be appropriately selected, such as by separately attaching a magnetic material such as a magnetic plate to the most downstream layer thickness regulating member 6, or by forming the most downstream layer thickness regulating member 6 itself from a magnetic material. . Regarding the layer thickness regulating member 7 other than the most downstream layer thickness regulating member 6, the presence or absence of the magnetic body 8 is not particularly limited.

Further, the installation positions of the layer thickness regulating members 6 and 7 are as follows.
As long as the region between the most downstream layer thickness regulating member 6 and the most upstream layer thickness regulating member 7 is disposed so as to face the center of the trimming magnetic pole 4a, it may be appropriately selected. The angle formed by the most upstream layer thickness regulating member 7 is smaller than the angle formed by two points having a magnetic force of 60% of the maximum magnetic force of the trimming magnetic pole 4a, and at least one of the plurality of layer thickness regulating members 6 and 7 has the trimming magnetic pole 4a. 60% of maximum magnetic force
As described above, it is more preferable to face the portion having a magnetic force of 70% or more.
And the most upstream layer thickness regulating member 7 is the trimming magnetic pole 4a.
It is preferable to face a portion having a magnetic force of 60% or more, more preferably 70% or more of the maximum magnetic force of the above. here,
If the thickness of the layer thickness regulating members 6 and 7 is less than 60%, it is necessary to reduce the trimming gap in order to form the developer layer in a thin layer.

When the amount of developer per unit area passing through the most downstream layer thickness regulating member 6 is Mlow and the amount of developer per unit area passing through the most upstream layer thickness regulating member 7 is Mup, It is preferable to satisfy the relationship of ≦ Mup / Mlow ≦ 10. That is, the setting position of the trimming gap is
The amount of the developer passing through the most upstream portion (the position of the most upstream layer thickness regulating member 7) is set to be larger than the amount of the developer passing through the most downstream portion (the position of the most downstream layer thickness regulating member 6). The ratio is more preferably 2 times or more and 10 times or less. If it is less than 2 times, the effect of widening the trimming gap cannot be obtained. If it exceeds 10 times, the developer accumulates or overflows between the plurality of layer thickness regulating members 6 and 7, so that excessive stress is applied to the developer. Giving is not preferred.

Next, the operation of the above technical means will be described. In FIG. 1, a plurality of layer thickness regulating members 6 and 7 are arranged so as to sandwich the maximum point of the magnetic force of the trimming magnetic pole 4a between the most downstream layer thickness regulating member 6 and the most upstream layer thickness regulating member 7, and The magnetic body 8 is arranged at least on the most downstream layer thickness regulating member 6. In the layer thickness regulating means 5 having such a configuration, the two-component developer G is provided with a plurality of layer thickness regulating members 6.
7, the two-component developer G on the developer carrier 1
Are sequentially formed at a plurality of locations. Further, since the magnetic force of the trimming magnetic pole 4a is mainly concentrated between the magnetic material 8 of the most downstream layer thickness regulating member 6 and the magnetic restriction of the two-component developer G at the trimming gap portion of the most downstream layer thickness regulating member 6. The force acts, and the two-component developer G passes through the trimming gap portion of the lowermost layer thickness regulating member 6 with the ears standing. Therefore, even if the most downstream layer thickness regulating member 6 has a wide trimming gap, the developer layer on the developer carrier 1 is formed as a thin layer.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the accompanying drawings. FIG. 2 is a schematic configuration diagram of an electrophotographic image forming apparatus equipped with an embodiment of the developing device according to the present invention. Referring to the figure, the image forming process of the image forming apparatus will be described. For example, the surface of a latent image carrier 11 composed of a photosensitive drum or the like is uniformly charged to a negative polarity by a uniform charger 12 such as a scorotron. You. Next, image exposure corresponding to the image is performed by an exposure device 13 such as a laser scanning device, and an electrostatic latent image corresponding to the image is formed on the surface of the latent image carrier 11. Furthermore,
The developing device 14 is of a magnetic brush developing type using a two-component developer (a developer composed of a toner and a carrier), and the magnetic brush rubs the electrostatic latent image to form the latent image carrier 1.
1 to form a toner image.

Next, a transfer material 15 such as a paper or a transparent sheet is conveyed from a paper feed tray (not shown) by a delivery roll, and once its tip is stopped by a registration roll (not shown), and then is moved to a predetermined position. It is sent to the transfer position at the timing. The transferred transfer material 15 comes into close contact with the toner image on the latent image carrier 11, and after the toner image is transferred onto the transfer material 15 by the action of a transfer device 16 such as a corotron, a charge removing device 17 such as a corotron is used. After the toner image is peeled off from the latent image carrier 11, the toner image is fixed on the transfer material 15 by a fixing device (not shown), and then carried out of the image forming apparatus. After the transfer, the latent image carrier 11 is
After the cleaning pretreatment is performed as necessary, the residual toner on the surface of the latent image carrier 11 is scraped off by the cleaning device 18. In FIG. 2, reference numeral 19 denotes a transfer pre-processing unit provided as needed and adjusting the charge of the developed toner image to facilitate transfer.

Next, details of the developing device used in the present embodiment are shown in FIGS. In FIG. 3, the developing device 1
Reference numeral 4 denotes a developing housing 21 having an opening at a portion facing the latent image carrier 11. A developing roll 22 is disposed at a position facing the opening of the developing housing 21, and a developing roll 22 is provided on the rear side of the developing roll 22. Is provided with a pair of developer stirring and conveying members 23 and 24 for stirring and conveying the developer G, and further, a developing area of the developing roll 22 (an area opposed to the latent image carrier 11 and in which development is effectively performed). A layer thickness regulating component 25 for the developer G is disposed on the front side (upstream side) of FIG. Reference numeral 26 denotes a toner cartridge for replenishing the developing housing 21 with toner.

In this embodiment, the developing roll 22
As shown in FIG. 4, the developing sleeve 22 includes a non-magnetic rotatable developing sleeve 221 and a magnet roll 222 fixed and installed in the developing sleeve 221.
The developing sleeve 221 is rotated by a drive motor (not shown) while maintaining a predetermined developing interval between the developing sleeve 1 and the peripheral surface of the latent image carrier 11. Note that there may be a mode in which the developing sleeve 221 and the latent image carrier 11 are arranged in contact with each other. A plurality of magnetic poles are arranged in an appropriate pattern on the magnet roll 222. In the present embodiment, the developing magnetic pole S1 is disposed at a position corresponding to the developing area, and a transport magnetic pole N1 for transporting the developer and an upstream of the transport magnetic pole N1 are arranged upstream of the developing magnetic pole S1. Thickness regulation parts 2
5, a trimming magnetic pole S for forming a developer layer is formed.
2, and a pair of separation magnetic poles N2 and N3 having the same polarity for separating the residual developer G from the development roll 22 is disposed downstream of the development area.

In this embodiment, the pair of developer stirring / conveying members 23 and 24 is a screw member (screw structure) also serving as a stirring member rotating in directions opposite to each other. The toner supplied from the toner cartridge 26 is transported by the thrust, and the developer G is transported and circulated in the opposite directions to sufficiently stir and mix the toner and the carrier. The developer is applied on the peripheral surface of the developing sleeve 221 in a layered manner.

Particularly, in the present embodiment, the layer thickness regulating component 2
4, a pair of layer thickness regulating members 251 and 252 arranged side by side with respect to the rotation direction of the developing roll 22, as shown in FIG. A magnetic plate 251b is attached to a portion of the surface of the surface 251a facing the upstream layer thickness regulating member 252 near the front end, and the upstream layer thickness regulating member 252 is an upstream side surface of the nonmagnetic plate 252a having a predetermined thickness. Plate 2 near the tip
What bonded 52b is used. In this embodiment, the non-magnetic plate 2 is used as the upstream layer thickness regulating member 252.
A member consisting of only 52a may be used. The layer thickness regulating members 251 and 252 are held with a predetermined trimming gap between them and the developing sleeve 221.
In particular, in the present embodiment, the trimming gap of the downstream layer thickness regulating member 251 is, for example, 0.9 mm, and the trimming gap of the upstream layer thickness regulating member 252 is, for example, 1.0 mm.
It is set to 4 mm.

Further, in the present embodiment, the two layer thickness regulating members 251 and 252 are arranged so as to sandwich the center of the trimming magnetic pole S2 of the magnet roll 222. The center of the trimming magnetic pole S2 here means two distribution points which measure the radial component of the magnetic flux density of the magnetic pole and show a magnetic flux density of 80% with respect to the maximum magnetic force. FIG. 5 shows magnetic force patterns 1 of various trimming magnetic poles S2.
The positions C1, C2, and C3 of the center of the magnetic pole in the cases of (1) to (3) are illustrated.

According to the present embodiment, the two-component developer G on the surface of the developing sleeve 221 is provided with the double-layered layer thickness regulating member 251 provided to face the trimming magnetic pole S2 of the magnet roll 222. , 252 to form a uniform developer layer. Then, the uniformly formed developer layer develops a latent image on the peripheral surface of the latent image carrier 11 in a development area to form a predetermined toner image. When the performance of forming the developer layer at this time was evaluated, it was confirmed that the developing device according to the present embodiment was excellent, as is clear from the results of Examples and Comparative Examples described later. However, the amount of the developer passing through the layer thickness regulating member 25 is such that the amount of the developer passing through the upstream layer thickness regulating member 252 is larger than the amount of the developer passing through the downstream layer thickness regulating member 251. It is preferable to set the ratio to 2 times or more and 10 times or less.

[0023]

【Example】

Example 1 In this example, as shown in FIG.
1 (corresponding to the downstream layer thickness regulating member 251 in FIG. 4), the layer thickness regulating member T2 (corresponding to the upstream layer thickness regulating member 252 in FIG. 4)
For both the upstream side and the downstream side, a magnetic stainless plate having a thickness of 0.4 mm and a height of 4 mm was attached to the front end of a non-magnetic metal plate having a thickness of 1 mm, with the lower surfaces thereof together. FIG. 6 shows the radial distribution of the magnetic flux density of the trimming magnetic pole S2 of the developing roll 22 of this embodiment. FIG.
As shown in the figure, the maximum magnetic force of the trimming magnetic pole S2 is 50 m.
There was T. The magnetic pole center is at the point of 80% magnetic force, ie, 40 m
This is the center (C1) of the line connecting the points of T. Two layer thickness regulating members T1 and T2 are arranged so as to sandwich the center of the magnetic pole. Further, the angle b between the two layer thickness regulating members T1 and T2
Is smaller than the angle a formed by the point of 60% magnetic force, that is, two points of 30 mT, and both the two-layer thick-layer regulating members T1 and T2 are opposed to a point of 30 mT or more. In the present embodiment, the angle a is set to 30 degrees, the angle b is set to 18 degrees, and the magnetic pole center C1 is set to a position deviated by + 10 ° from the layer thickness regulating member T1. Actually, as shown in FIG. 7, when the developing device is mounted on the image forming apparatus, the layer thickness regulating parts are arranged such that the downstream layer thickness regulating member T1 is in the 12 o'clock direction of the timepiece. .

At this time, as shown in FIG. 8, the upstream side of the trimming gap is 1.4 mm, and the downstream side is 0.9 mm.
mm, the amount of developer on the developing sleeve when trimming is performed only on the upstream side is 120 g.
/ M ² , the amount of developer on the developing sleeve when two sheets were installed was 35 g / m ² . Then, in the present embodiment, when a predetermined number of continuous copies were performed, it was confirmed that high image quality was stably obtained over a long period of time. Specifically, no unevenness was observed in the halftone portion after continuous printing of 5,000 sheets of blank paper, and no fog was observed in the background portion even after continuous copying of 100,000 sheets.

Embodiment 2 The present embodiment has substantially the same configuration as that of Embodiment 1 except that the magnetic stainless steel plate of the upstream layer thickness regulating member T2 is removed. At this time, as shown in FIG. 8, the upstream side of the trimming gap is 1.4 mm, and the downstream side is 0.1 mm.
8 mm, the amount of developer on the developing sleeve when trimming was performed only on the upstream side was 200 mm.
g / m ² , and the amount of developer on the developing sleeve when two sheets were installed was 35 g / m ² . Then, in this embodiment,
When a predetermined number of continuous copies were performed, it was confirmed that high image quality was stably obtained over a long period of time.

Comparative Example 1 This comparative example is a model using one layer thickness regulating member.
As shown in FIGS. 7 and 8, the developer layer is regulated only by the downstream layer thickness regulating member T1. At this time, in order to obtain the same amount of the developer on the developing sleeve of 35 g / m ² as in the first and second embodiments, the trimming gap is set to 0.1.
It was necessary to set it to 65 mm. For this reason, in this comparative example, when a predetermined number of continuous copies were performed, it was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with the first and second embodiments. Specifically, 5,
Unevenness was observed in the halftone area after continuous running of 000 sheets of white paper, and fog in the background was observed after continuous copying of 100,000 sheets.

Comparative Example 2 As shown in FIGS. 7 and 8, this comparative example has basically the same configuration as that of the first embodiment, but is different from the first embodiment. The magnetic stainless steel plate is removed. At this time, the upstream trimming gap is set to 1.4 mm, and the downstream trimming gap is set to 0.45 mm in order to obtain the same amount of developer on the developing sleeve of 35 g / m ² as in the first embodiment. Was needed. For this reason, in this comparative example, when a predetermined number of continuous copies were performed, it was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with the first and second embodiments.

Comparative Example 3 As shown in FIGS. 7 and 8, this comparative example has a structure basically similar to that of the first embodiment. However, unlike the first embodiment, the position of the upstream layer thickness regulating member is different from that of the first embodiment. To the further upstream side (+
36 °), and the angle between the downstream layer thickness regulating member T1 and the upstream layer thickness regulating member T3 is larger than the angle between two points having a magnetic force of 60% of the maximum magnetic force of the trimming magnetic pole. At this time, the upstream trimming gap is set to 1.4 mm, and the downstream trimming gap is set to 0.65 mm in order to obtain the same amount of developer on the developing sleeve of 35 g / m ² as in the first embodiment. Was needed. For this reason, in this comparative example, when a predetermined number of continuous copies were performed, it was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with the first and second embodiments.

Comparative Example 4 As shown in FIGS. 7 and 8, this comparative example has basically the same configuration as that of the first embodiment, but differs from the first embodiment in that the center position of the trimming magnetic pole is changed to the layer thickness. C2 is deviated by 20 ° from the regulating member T1, so that the center of the trimming magnetic pole does not face the intermediate region between the layer thickness regulating members T1 and T2. At this time, the same as in Example 1, 120 g / m
^{2. In} order to obtain the amount of developer on the developing sleeve of 35 g / m ² on the downstream side, the upstream trimming gap is set to 1.6 m.
m, and it was necessary to set the trimming gap on the downstream side to 0.5 mm. For this reason, in this comparative example, when a predetermined number of continuous copies were performed,
It was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with 2.

Comparative Example 5 As shown in FIGS. 7 and 8, this comparative example has a structure basically similar to that of the first embodiment, but differs from the first embodiment in that the center position of the trimming magnetic pole is set to the layer thickness. C3 is deviated by −2 ° from the regulating member T1 so that the center of the trimming magnetic pole does not face the intermediate region between the thickness regulating members T1 and T2. At this time, the same as in Example 1, 120 g / m
^2. To obtain the amount of developer on the developing sleeve of 35 g / m ² on the downstream side, the trimming gap on the upstream side should be 0.6 m
m, and it was necessary to set the trimming gap on the downstream side to 0.9 mm. For this reason, in this comparative example, when a predetermined number of continuous copies were performed,
It was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with 2.

Comparative Example 6 As shown in FIGS. 7 and 8, this comparative example has a structure basically similar to that of the first embodiment, but is different from the first embodiment. The amount of developer is less than twice that of the downstream side (in this example, 60 g / m ² for 35 g / m ² on the downstream side).
m ² ). At this time, in order to obtain the same amount of developer on the developing sleeve of 35 g / m ² on the downstream side as in the first embodiment, the trimming gap on the upstream side is set to 0.5 mm, and the trimming gap on the downstream side is set to 1.1 mm. It was necessary to set. For this reason, in this comparative example,
When a predetermined number of continuous copies were executed, it was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with the first and second embodiments.

Comparative Example 7 As shown in FIGS. 7 and 8, this comparative example has a structure basically similar to that of the first embodiment, but is different from the first embodiment. The developer amount exceeds 10 times that of the downstream side (in this example, 40 g for 35 g / m ² on the downstream side).
0 g / m ² ). At this time, in order to obtain the same amount of developer on the developing sleeve of 35 g / m ² on the downstream side as in the first embodiment, the upstream side trimming gap is set to 2.5 mm, and the downstream side trimming gap is set to 0.6 mm.
mm. For this reason, in this comparative example, when a predetermined number of continuous copies were performed, it was confirmed that the period during which high image quality was stably obtained was significantly shortened as compared with the first and second embodiments.

[0033]

As described above, according to the present invention,
Since the developer layer is formed by both the smoothing effect of the developer layer by the plurality of layer thickness regulating members and the magnetic binding force by the trimming magnetic pole pattern, the developer layer is compared with the conventional configuration. Can be stably formed in a thin layer, and a high-quality image faithful to the electrostatic latent image can be obtained. In particular, in the present invention, even when the developer layer is formed as a thin layer, it is possible to keep the gap between the layer thickness regulating member and the developer carrier wide, without giving excessive stress to the developer. The developer layer can be formed as a thin layer. As a result, high image quality can be stably obtained over a long period of time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a schematic configuration of a developing device according to the present invention.

FIG. 2 is an explanatory diagram illustrating an example of an image forming apparatus into which an embodiment of a developing device to which the present invention has been applied is incorporated;

FIG. 3 is an explanatory diagram illustrating an overall configuration of a developing device according to the embodiment.

FIG. 4 is an explanatory diagram showing a configuration example of a layer thickness regulating component of the developing device according to the embodiment.

FIG. 5 is an explanatory diagram showing a magnetic force central portion with respect to various magnetic force patterns of the trimming magnetic pole in the embodiment.

FIG. 6 is an explanatory diagram illustrating a relationship between a magnetic force pattern of a trimming magnetic pole and a position of a layer thickness regulating member of the developing device according to the first embodiment.

FIG. 7 is an explanatory diagram showing a layout of a layer thickness regulating member and a magnetic pole center in each of Examples and Comparative Examples.

FIG. 8 is an explanatory diagram showing a layer regulating portion configuration, the presence or absence of a magnetic member (magnetic plate), a developer passage amount, a trimming gap, and evaluation judgment in each of Examples and Comparative Examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Developer carrier, 2 ... Developing sleeve, 3 ... Magnet member,
4 magnetic pole, 4a trimming magnetic pole, 5 layer thickness regulating means,
6 ... most downstream layer thickness regulating member, 7 ... most upstream layer thickness regulating member, 8
... magnetic material, m ... development area, Z ... electrostatic latent image, 22 ... development roll, 221 ... development sleeve, 222 ... magnet roll, S1-S2, N1-N3 ... magnetic pole, S2 ... trimming magnetic pole,
25 ... layer thickness regulating component, 251 ... downstream layer thickness regulating member, 2
52: upstream layer thickness regulating member, 251a, 252a: non-magnetic plate, 251b, 252b: magnetic plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasunori Uneda 2274 Hongo, Fuji Xerox Co., Ltd., Ebina City, Kanagawa Prefecture

Claims (4)

[Claims] 1. A developing device for visualizing an electrostatic latent image (Z) in a developing area (m) using a two-component developer (G) comprising at least a magnetic carrier and a toner. (G) is a rotatable developing sleeve (2) and a magnet member (3) fixedly provided inside the developing sleeve (2) and having a plurality of magnetic poles (4) arranged therearound. A developer carrier (1); and a layer thickness regulating means (5) disposed opposite to the developer carrier (1) and regulating the layer thickness of the developer (G) on the developer carrier (1). The layer thickness regulating means (5) includes a plurality of layer thickness regulating members (6, 7) arranged in parallel along the rotation direction of the developer carrier (1), and rotates the developer carrier (1). A magnetic body (8) is provided on at least a part of the most downstream layer thickness regulating member (6) located on the most downstream side in the direction, The region between the most downstream layer thickness regulating member (6) located on the most downstream side in the rotation direction of the developer carrying member (1) and the most upstream layer thickness regulating member (7) located on the most upstream side is magnetized. A developing device characterized in that the magnetic pole (4) of the member (3) is disposed so as to face the center of a trimming magnetic pole (4a) arranged in front of the developing area (m). 2. The developing device according to claim 1, wherein the angle between the most downstream layer thickness regulating member and the most upstream layer thickness regulating member is 60% of the maximum magnetic force of the trimming magnetic pole. And wherein at least one of the plurality of layer thickness regulating members (6, 7) faces a portion having a magnetic force of 60% or more of the maximum magnetic force of the trimming magnetic pole (4a). Developing device. 3. The developing device according to claim 1, wherein both the most downstream layer thickness regulating member and the most upstream layer thickness regulating member have the maximum magnetic force of the trimming magnetic pole.
A developing device facing a portion having a magnetic force of 0% or more. 4. The developing device according to claim 1, wherein the amount of developer per unit area passing through the most downstream layer thickness regulating member is Mlow, and the unit area passing through the most upstream layer thickness regulating member is. When the developer amount per unit is Mup, 2 ≦
A developing device, wherein a relationship of Mup / Mlow ≦ 10 is satisfied.