JP2003295549A - Small-diameter conductive brush roll for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a device especially a tandem-type color machine by reducing the diameter of a conductive brush roll to be used for charging, transferring, electricity removal and a cleaner of an electrophotographic image forming apparatus, and to attain cost reduction with the reduction of the diameter while keeping performance. <P>SOLUTION: In the conductive brush roll formed by winding a pile texture with a conductive filament yarn as a pile on a shaft 4, the single yarn of the conductive filament yarn to be used is 3D or more to meet L/A>3, thereby the conductive brush roll whose brush diameter ranges 7 to 12 mm is realized, where L110=(brush diameter - shaft diameter)/2, and A is the average interval 22 of adjacent bundles of the conductive filament yarns woven into the pile texture. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive brush roll, and more particularly to a small diameter conductive brush roll used for charging, discharging, transferring, cleaning, etc. used in an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art Electrophotographic image forming apparatuses have been widely used because the contact charging method using a conductive brush roll is ozoneless. In addition to the charging, the electrostatic brush is used not only for transfer but also for cleaning, so that a conductive brush roll may be used.

In such a conductive brush roll, a cloth called pile weave is slit into a certain width to form a ribbon-like cloth, which is spirally wound around a shaft and raised,
It is manufactured through processing steps such as shirring. At this time, a brush having a shaft diameter of 6 mm and a pile length of 5 mm having an outer diameter of about 16 mm has been most frequently used. Even with a small diameter, the outer diameter of the brush was about 13 mm.
Also, the request from the device side was sufficient at this level.

[0004]

By the way, the recent image forming apparatus is in the transition period from the monochrome machine to the full-color machine, and the development competition of the color machine is intensifying. Among the color machines, the tandem type, which has a high printing speed, is becoming the mainstream. However, since four sets of process units are required, there is a strong demand for downsizing of the members constituting the process unit. There is an increasing demand for a smaller diameter of the charging brush roll that charges the photoconductor, and the outer diameter is 10 m.
In some extreme cases, there was a demand for 8 mm.

However, since the charging brush roll is a component that directly affects the image quality, it is not allowed to sacrifice the performance, and it is impossible to reduce the outer diameter to 12 mm or less on the conventional extension line. The reason will be described below. Usually, the brush uses a pile woven material having filament yarn as a pile. The filament yarn is manufactured by an aggregate of a plurality of filaments. For example, the conductive yarn of rayon, which has been used for a charging brush, is manufactured by an assembly of 100 filaments, that is, a bundle of 100 filaments. Even when this yarn is pile-weaved, it is woven in this bundle. FIG. 4 is a cross-sectional view of the pile woven fabric in the weaving direction. As shown in the figure, a conductive filament yarn is woven into the weft yarn 104 as a pile yarn 102 while being entwined in a W shape. The pile yarn 102 of a 100-filament bundle is converged at the base cloth portion 106, but is released at the pile portion 108 and spreads toward the tip. And the pile section 1
When the length of 08 is L110 or more, it overlaps with the spread of the filaments forming the adjacent piles. In such a state, the surface of the tip of the pile portion 108 is
Two filaments are evenly distributed. However, when the length of the pile portion 108 is L110 or less, a gap is formed between the pile yarns 102 and the spread of the bundle of the adjacent pile yarns 102. Therefore, the distribution of filaments on the surface of the tip of the pile portion 108 becomes uneven. This uneven distribution of filaments
As a charging brush, it impairs the uniform charging of the body to be charged, resulting in fatal damage.

The filament density of the conventional charging brush, which is 100,000 filaments per inch ² , has been used as a high density product close to the limit as a pile weave. At this time, the thickness of one filament (hereinafter referred to as “single yarn”) is 6 denier. The density of the bundle is 1 because it is woven in a bundle of 100 filaments.
There are 1000 bundles per inch ² and 1.55 bundles per mm ² . Unlike pile weave its perpendicular arrangement to the weaving direction of the bundle of fabric, also woven but not necessarily uniform placement on the specifications, per 1 mm ^2,
The flock density of 1.55 bundles is equal to the average spacing A between adjacent bundles.
112 is about 0.8 mm.

At this time, in order to make the filament distribution on the brush surface uniform, the length L110 of the pile portion 108 is set.
Has been empirically known to require at least 2.5 mm, preferably 3 mm or more. Thickness T1 of the base cloth portion 106
Although not shown, 14 is about 1 mm when the thickness of the back coat layer on the back surface of the base cloth portion and the thickness of the double-sided adhesive tape for adhering to the shaft are included. Therefore, the minimum value of the brush outer diameter is the shaft diameter + (T114 + L110) × 2, and when the shaft diameter is 5 mm, 5+ (1 + 2.
5) × 2 = 12 That is, the minimum brush outer diameter is 12
mm. Even if the specifications of the brush change slightly, the minimum brush diameter does not change so much.

[0008] Further, along with the downsizing and cost reduction of the device, the demand for cost reduction of parts is also increasing, but in this respect, there is a limit in the conventional extension line. The present invention has been made to solve such a problem, and an object thereof is to provide a small-diameter conductive brush having a small outer diameter at a lower cost without sacrificing performance.

[0009]

In order to achieve the above object, the present invention provides an electrophotographic conductive brush roll formed by winding a pile woven fabric having conductive filament yarn as a pile on a shaft. Is 12 mm or less, the single filament of the conductive filament yarn is 3 denier or less, and L / A> 3. However, L = (brush outer diameter-shaft diameter)
/ 2, A is the average spacing between adjacent bundles of the conductive filament yarns woven into the pile fabric.
In the present invention, the outer diameter of the conductive brush roll is 7 to 12 mm.
Therefore, the diameter was significantly reduced compared to the conventional product. Further, the material cost and the processing cost can be reduced, and the image forming apparatus can be downsized and the cost can be reduced.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a charging brush 2 showing an example of a small diameter conductive brush roll for an image forming apparatus according to the present invention. This charging brush 2 has a shaft 4
Is formed by spirally winding a pile woven fabric, and the shaft 4 and the base fabric portion 6 of the fabric are bonded to each other via an adhesive layer 8 made of a double-sided adhesive tape or the like. Base cloth part 6
A pile portion 10 having a pile of conductive yarns is formed on the outer circumference of the pile portion.

The outer diameter of the shaft 4 is 4 to 6 mm.
The one used is 4 to 5 mm for A4,
In the case of A3 correspondence, it is properly used such as 5 to 6 mm. The outer diameter 12 of the charging brush 2 is 7 to 11 mm,
The thickness of the conductive yarn of the pile portion 10 is 3 denier or less,
It is preferably 2.5 denier or less. The total thickness of the adhesive layer 8 and the base cloth portion 6 is set to 0.5 mm or less. The pile length 14 of the brush is 1/2 of the value obtained by subtracting the value of the outer diameter 12 of the shaft 4 from the value of the outer diameter 12 of the brush for convenience. That is, the pile length 14 is a value obtained by combining the pile portion 10, the base cloth portion 6 and the adhesive layer 8. The pile length 14 of the charging brush 2 is 1.5 to
3 mm, preferably 2.5 mm or less is adopted.

Next, the pile woven material used for the charging brush 2 will be described with reference to FIG. As described above, in the past, 100 filament bundles each having a thickness of 6 denier, that is, 600 denier per bundle, were used as the conductive yarn of rayon, whereas in the present embodiment, the conductive yarn of nylon is used as the single yarn. 2 denier, 50 filament bundle, that is, 100 denier per bundle was used. This is because nylon has a higher thread strength than rayon and has a smaller denier that could not be realized with rayon. Further, the pile weaving machine was modified so that the thickness of the yarn of the base cloth was ½ or less of that of the conventional one, and the number of threads in the weaving direction and the weaving width direction was doubled or more. As a result, we succeeded in increasing the weave density of the bundle up to 6 times that of the conventional one. Therefore, the average distance between adjacent bundles was about 0.33 mm, which was less than half that of the conventional 0.8 mm. Therefore, the length L1 of the pile portion 10
For No. 10, the filament distribution on the surface of the tip of the pile portion 10 could be made uniform at about 1 mm. The pile length 14 including the base cloth portion 6 and the like was sufficient at 1.5 mm. Therefore, if this cloth is wound on a 4 mm shaft 4, the brush outer diameter will be 7 mm, and if it is wound on a 6 mm shaft 4,
The charging brush 2 having a brush outer diameter of 9 mm is realized. The smaller the brush outer diameter, the more important it is to make the single yarn denier smaller. When the outer diameter 12 is 7 to 8 mm, the effect is large when the outer diameter 12 is 1.5 to 2 denier. 11-12
If it is mm, 3 denier can be used.

This is because the nylon used in this embodiment has a higher yarn strength than rayon, and therefore it is possible to manufacture a finer conductive yarn. However, some new techniques have been adopted in order to maximize the thinness limit. It was adopted. Generally, fibers are processed on the assumption that they are used for clothing, but when used in a brush for an image forming apparatus, the strength of the yarn may be lower than that used in clothing. If the strength of the thread is not a problem,
This means that the draw ratio in the yarn manufacturing process may be reduced. If the draw ratio is reduced, thinner yarn can be produced. In addition, ordinary nylon yarn is cold drawn, but hot drawn. Thereby, a thinner and more stable conductivity was obtained. Specifically, while a general nylon yarn has a draw ratio of 2 to 3 times or more in the cold, in the present embodiment example, conductive nylon is 2 times or less in the heat of 150 ° C. level. The centrifugal ratio of This made it possible to reduce the thickness to 1.5 denier.

The conductive thread may be made of other material such as polyester in addition to nylon, and a thread thinner than the conventional product may be manufactured and employed based on the above-mentioned concept. Also, the number of filaments in one bundle is not limited to 50 filaments, and a smaller number of filaments is more effective and more flexible. However, it is difficult to reduce the single yarn denier and the number of filaments, and it is realistic to increase the number of filaments by reducing the single yarn denier.
If it is 1.5 denier, 30 to 100 filaments are preferable, and if it is 2 denier, 20 to 80 filament bundles are preferable.

As described above, the small-diameter conductive brush roll for an image forming apparatus according to the present embodiment can realize the charging brush 2 having a small diameter which has never existed in the prior art, so that it has a great effect on downsizing of the image forming apparatus. I was able to bring it. Particularly, in a tandem type color machine, since four sets of process units are required, miniaturization of components in the process unit greatly contributes to miniaturization of the apparatus. Further, by using the charging brush 2, a cleanerless system in which the cleaning member can be omitted can be adopted, and the size can be further reduced. Figure 2
FIG. 3 is a main part configuration diagram of an image forming apparatus of a tandem type color machine equipped with the charging brush 2 of the present invention. The photoconductor 16, the charging brush 2, the exposure 18, and the developing machine 20 constitute one process unit, and four sets of these are arranged horizontally.
When downsizing the apparatus, it is how to shorten the interval 22 between adjacent process units. Here, the outer diameter 12 of the charging brush 2 is 8 mm, and the outer diameter 12 of the photoconductor 16 is 12 mm.
Of 24 mm was used. As shown in the figure, in the cleanerless system, the space 22 between the process units is equal to that of the charging brush 2.
The outer diameter 12 and the outer diameter 12 of the photoconductor 16 were determined, and in this case, the interval 22 could be 34 mm. Even the entire set of 4 process units could be accommodated within the range of about 130 mm. This has never been possible before.

FIG. 3 is an external view of the charging brush 2 according to the second embodiment of the present invention. Similar to FIG. 1, the brush portion 24 is formed on the shaft 4, and the conductive yarns and the like are all the same as those in FIG. 1. However, the bristles 26 are partially present from the outer periphery of the brush portion 24. In the conventional example using the conductive yarn of 6 denier, such flying hairs 26 were fatal to uneven charging, but in the present embodiment, uneven charging did not occur. It is presumed that this is because the brush is in soft contact with the body to be charged because the conductive yarn of 2 denier level is used.

In this way, the bristles 2 protruding from the outer periphery of the brush portion
If 6 does not affect the uneven charging, the accuracy of the outer circumference of the brush portion 24 may be rough. In the conventional example, after the cloth is wound on the shaft 4, the shirring process for trimming the raised hair and the outer periphery is performed. However, in the present embodiment, the shirring process is not required and the pile length is 14
However, since it is shorter than the conventional example, the raising property in the state of the cloth is good, so that the raising process is not required. However, the raising of the hair is performed by centrifugal force to make a pile, and the effect of the centrifugal force is reduced in the small diameter brush, and the smaller the diameter, the more meaningless the raising process is. In this way, the processing steps can be omitted,
It was possible to bring about a significant reduction in processing costs.

[0018]

EXAMPLES As examples of the present invention, 17 types of charging brushes based on the above-described form examples and, as comparative examples, conventional types and 7 types of charging brushes conforming thereto were prepared and mounted on an image forming apparatus to evaluate image quality. I went. Table 1 is a summary of the results.

[Table 1] In Table 1, the outer diameter is the outer diameter of the brush, and the pile length L is a value obtained by subtracting the shaft diameter from the outer diameter by half, and the base cloth portion and the adhesive layer are added to the actual pile length. It was done. The fineness is the fineness of the conductive yarn to be the brush pile, F is the number of filaments in one bundle, and D is the denier in one bundle. Also, although the filament density and the bundle density of the conductive yarn are also shown, A is the average distance between the adjacent bundles of the woven bundle. The bundle density is 1 / A ² . Here, A is calculated from the fineness and the filament density. Then, the value of L / A, the evaluated image quality, and the cost ratio of the conductive yarn were also calculated and shown. Regarding the image quality, ◯ is good, x is bad, and Δ is slightly bad. The weight ratio of the conductive yarn required for each brush was calculated and used as the cost ratio.

Comparative Example 1 is a form of a charging brush that has been used most often in the past, and Comparative Examples 2 to 7 are:
The outer diameter of the brush is reduced based on this. The embodiment is in the form of a small diameter brush made based on the embodiment of the present invention. It can be seen from Table 1 that there is a correlation between the L / A value and the image quality. Also in the comparative example, if L / A is 4 or more, the image quality is good. The outer diameter of the brush is limited to 12 mm,
If it is less than that, the image quality deteriorates. On the other hand, in the embodiment, if L / A is 3 or more, almost good image quality is obtained. In the example, since the thickness of the base cloth is smaller than that of the comparative example, good image quality can be obtained even if L / A is smaller than that of the comparative example.

In Table 1, the cost ratio of the conductive yarn is shown. This shows the cost ratio of the conductive yarn of the brush of the other embodiment, where the cost of the conductive yarn of Comparative Example 1 is 1. In the case of the charging brush, the cost of the conductive yarn is the highest, and the cost of the conductive yarn greatly affects the cost of the charging brush. As can be seen from the above, in terms of the cost of the conductive yarn, the present embodiment is 20 to 3 of the conventional charging brush.
It could be reduced to 0%. Further, as described above, the number of man-hours can be reduced also in the processing step, and a very large cost reduction can be realized as a whole.

The charging brush has been described above in detail with respect to the embodiments and examples of the present invention. However, even a brush such as a cleaning brush, a transfer brush or a charge eliminating brush in an electrophotographic image forming apparatus has a small diameter. The necessity of a uniform brush is the same as that of the charging brush, and the same effect can be obtained even when the present invention is used for such an application, and thus is included in the present invention.

[0022]

As described above, the small diameter conductive brush roll for an image forming apparatus of the present invention has a brush outer diameter of 7 to 12.
The diameter can be made smaller, and the diameter can be greatly reduced compared to the conventional one. Therefore, this is particularly effective for an image forming apparatus that requires four sets of process units such as a tandem type color machine. In addition, the number of processing steps can be reduced while reducing the diameter, and the most expensive material such as conductive yarn can be reduced, resulting in a large reduction in the price of the brush.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a charging brush showing an example of a small diameter conductive brush roll for an image forming apparatus according to the present invention.

FIG. 2 is a configuration diagram of a main part of an image forming apparatus of a tandem type color machine equipped with a charging brush of the present invention.

FIG. 3 is an external view of a charging brush according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view in the weaving direction of the pile woven fabric.

[Explanation of symbols]

2 ... Charging brush, 4 ... Shaft, 6 ... Base cloth part, 8 ... Adhesive layer, 10 ... Pile part, 12 ... Outer diameter, 14 ... Pile length, 1
6 ... Photoconductor, 18 ... Exposure, 20 ... Developing machine, 22 ... Interval,
24 ... brush part, 26 ... protruding bristles, 102 ... pile yarn,
104 ... Weft, 106 ... Base cloth part, 108 ... Pile part, 1
10 ... L, 112 ... Interval A, 114 ... T.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/06 G03G 21/00 340 21/10 314 F term (reference) 2H035 AA14 AB01 AB02 AB03 AZ01 2H134 GA01 GB01 HB01 HB03 HB19 KD04 KE01 KG01 KG04 KG05 KG08 KH03 KH10 KJ02 2H171 FA11 FA15 FA17 FA18 GA03 GA04 GA15 QB04 QB07 QB09 QC03 QC14 QC23 QC25 JA23 GA45 HA08 GA23B AHABWA25B AWAB WA25 WA08 WA12 WA02 WA08 WA09 WA02 WA09 WA09 WA02 WA09 WA08 WA09 WA09 WA09 WA09 WA08 WA09 WA09 WA08 WA09 WA09 WA09 WA08 WA09 WA02 WA08 WA09 WA09 WA08 WA09 WA08 WA09 WA02 WA08 WA09 WA08 WA09 WA02 WA08 WA12 JA25 JA26 MA02 MA20 MB01 3B202 AA30 AB03 BA03 BC01 EA01

Claims (3)

[Claims] 1. An electrophotographic conductive brush roll formed by winding a pile woven fabric having conductive filament yarn as a pile on a shaft, and having a brush outer diameter of 12 mm.
Below, the number of single filaments of the conductive filament yarn is 3
A small diameter conductive brush roll for an image forming apparatus, which has a denier or less and L / A> 3. However, L = (brush outer diameter-shaft diameter) / 2, A
Is the average spacing between adjacent bundles of the conductive filament yarns woven into the pile fabric. 2. The small diameter conductive brush roll for an image forming apparatus according to claim 1, wherein a raising step is omitted in the manufacturing process of the conductive brush roll. 3. The small diameter conductive brush roll for an image forming apparatus according to claim 1, wherein the raising process and the shearing process are omitted in the manufacturing process of the conductive brush roll.