JP2018022021A - Developing blade and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing blade including an elastic member that is excellent in both charge-providing performance to toner and wear resistance, and can form good images over a long period.SOLUTION: A developing blade comprises a long-shaped plate and an elastic member that is arranged on the long-shaped plate along the longitudinal direction of the plate. The elastic member includes ends respectively located on both ends in the longitudinal direction and a center part located between the ends. At least one side in the width direction of the center part is formed by using a silicone resin, and the ends are formed by using a resin having a higher wear resistance than that of the silicone resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developing blade used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and an image forming apparatus including the developing blade.

  Conventionally, in an image forming apparatus employing an electrophotographic method or an electrostatic recording method such as a copying machine, a printer, a facsimile, etc., as a member that regulates the layer thickness of toner supplied to the surface of the developing roller and performs frictional charging, A developing blade is used.

  Specifically, toner is attached to the electrostatic latent image formed on the photosensitive drum via a developing roller to visualize the electrostatic latent image, and then the visualized image (toner image) is transferred from the photosensitive drum to paper or the like. In a conventional image forming apparatus that transfers an image to a recording medium and forms an image, the developing blade is used to regulate the toner supplied to the surface of the developing roller to a uniform thickness and to frictionally charge the toner. ing.

  And as a developing blade, what has arrange | positioned the elastic member which contacts a developing roller along the longitudinal direction of a plate on the single side | surface of an elongate metal thin plate is used. As the elastic member that contacts the developing roller, an elastic member formed using urethane resin or an elastic member formed using silicone resin is used (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 4-86852

  However, a developing blade having an elastic member formed using urethane resin cannot sufficiently increase the charge amount of toner, and image quality is higher than that of a developing blade having elastic member formed using silicone resin. There was a problem of being inferior.

  On the other hand, a developing blade having an elastic member formed using a silicone resin can sufficiently charge the toner to form a good image, but the elastic member has low wear resistance and is used for a long time. When contacted with the developing roller, the end of the elastic member that is particularly susceptible to load may be worn, causing problems such as toner leakage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a developing blade that includes an elastic member that is excellent in both charge imparting property and abrasion resistance to toner and that can form a good image over a long period of time.
Another object of the present invention is to provide an image forming apparatus capable of forming a good image over a long period of time.

An object of the present invention is to advantageously solve the above-described problems. A developing blade according to the present invention includes a long plate and a long plate on the long plate along the longitudinal direction of the plate. A developing blade provided with an elastic member, wherein the elastic member includes end portions located on both ends in the longitudinal direction and a central portion located between the both end portions, and the central portion includes at least One side in the width direction is formed using a silicone resin, and the end portion is formed using a resin having higher wear resistance than the silicone resin. Thus, if at least one side in the width direction of the central portion of the elastic member is formed using silicone resin, the one side in the width direction of the elastic member is brought into contact with the developing roller and is formed using silicone resin. A satisfactory image can be formed by sufficiently charging the toner at the portion. Further, if the end portion of the elastic member is formed using a resin having high wear resistance, it is possible to suppress wear of the end portion of the elastic member that is particularly likely to be loaded when contacting the developing roller. Therefore, it is possible to obtain a developing blade that is excellent in both charge imparting property and abrasion resistance for the toner.
In the present invention, the “abrasion resistance” of the resin can be evaluated by conducting a Taber abrasion test in accordance with JIS K7204. The smaller the abrasion amount, the higher the abrasion resistance.

  Here, in the developing blade of the present invention, it is preferable that the end portion and the central portion are integrally formed. This is because if the end portion and the central portion constituting the elastic member are integrated, the toner can be prevented from leaking from between the end portion and the central portion.

  In addition, the developing blade of the present invention is preferably formed using the high wear-resistant resin and has a region connected to at least one of the end portions in the central portion. In the elastic member in which the end and the center are integrally molded, if the region formed using the same resin as the end extends from the end to the center, the end and the center are good. This is because it is possible to prevent the central portion and the end portion from peeling off during use of the developing blade.

  In the developing blade of the present invention, it is preferable that the region extends between both end portions. If the region formed using the same resin as the end portion extends between both end portions, an elastic member in which the end portion and the central portion are well bonded can be easily formed on the plate. Because.

In the developing blade of the present invention, it is preferable that the maximum height of the region is lower than the maximum height of a portion formed using the silicone resin. If the maximum height of the region formed using the same resin as the end portion is made lower than the maximum height of the portion formed using the silicone resin, the portion formed using the silicone resin by contact with the developing roller Since the region formed using the same resin as the end portion can be prevented from coming into contact with the developing roller when it wears out, a good image can be formed over a longer period. It is.
In the present invention, “height” refers to a distance measured in a direction perpendicular to the surface of the plate from the surface of the plate on which the elastic member is provided.

  Furthermore, in the developing blade of the present invention, it is preferable that the elastic member has a notch at a position on one side in the width direction of the end portion and adjacent to the central portion. This is because if the notch is provided, excess toner can be discharged well when the developing blade is brought into contact with the developing roller to regulate the toner layer thickness. Moreover, in the elastic member having a notch, the wear resistance is particularly improved when the end portion is formed using a resin having higher wear resistance than the silicone resin.

  Here, in the developing blade of the present invention, the resin having high wear resistance includes a non-foamed urethane resin. This is because the non-foamed urethane resin is excellent in wear resistance.

  In the developing blade of the present invention, it is preferable that seal members are adjacently disposed on both sides in the longitudinal direction of the elastic member. If the seal member is provided, it is possible to prevent the toner from leaking out from both sides in the longitudinal direction of the elastic member when the developing blade is brought into contact with the developing roller to regulate the layer thickness of the toner.

Another object of the present invention is to advantageously solve the above-described problems, and an image forming apparatus according to the present invention includes any one of the developing blades described above, the elastic member of the developing blade, and the elastic members. A developing roller abutting on one side in the width direction, wherein the central portion of the elastic member is disposed at a position corresponding to the image forming area. Thus, if the developing blade described above is used and the central portion of the elastic member of the developing blade is arranged at a position corresponding to the image forming area, the portion formed using the silicone resin is used. The toner can be sufficiently charged and a good image can be formed over a long period of time.
In the present invention, the “position corresponding to the image forming area” refers to a position where the toner used for image formation can be charged.

According to the present invention, it is possible to provide a developing blade that includes an elastic member that is excellent in both charge imparting property and abrasion resistance to toner and that can form a good image over a long period of time.
In addition, according to the present invention, it is possible to provide an image forming apparatus capable of forming a good image over a long period of time.

2A and 2B are diagrams illustrating an example of a configuration of a developing blade according to the present invention, in which FIG. 1A is a plan view, FIG. 1B is a front view, and FIG. 1C is a cross-sectional view taken along line II in FIG. . FIG. 2 is an explanatory diagram illustrating a partial configuration of an image forming apparatus to which the developing blade illustrated in FIG. 1 is applied. (A) And (b) is a top view which shows the structure of the modification of the image development blade shown in FIG. (A)-(c) is a top view which shows the structure of the other example of the image development blade according to this invention. It is a top view which shows the structure of another example of the image development blade according to this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals have the same configuration.

Here, FIG. 1 shows a developing blade 10 as an example of the present invention.
As shown in the plan view of FIG. 1A, a developing blade 10 according to an example of the present invention is provided with a long plate 1 and a long plate 1 along a longitudinal direction X of the plate 1. And an elastic member 2 provided. The developing blade 10 regulates the layer thickness of the toner supplied to the surface of the developing roller by bringing the elastic member 2 into contact with the developing roller in an image forming apparatus such as a copying machine, a printer, or a facsimile machine. Used as a member for frictional charging of toner.
Note that the elastic member 2 on the plate 1 is elastically provided with seal members 3 for preventing toner leakage from both sides in the longitudinal direction of the elastic member 2 at both longitudinal portions of the elastic member 2 (portions indicated by broken lines in FIG. 1A). You may arrange | position adjacent to the member 2. FIG.

Here, the plate 1 of the developing blade 10 is not particularly limited, and can be formed using a thin metal plate (for example, a SUS plate or a phosphor bronze plate). Moreover, the dimension of the longitudinal direction X of the plate 1 can be 200-300 mm, for example, the dimension of the width direction Y can be 10-20 mm, for example, and thickness can be 0.08-0.15 mm. be able to.
The plate 1 has two notches 11 separated from each other at a part of the edge 1a on one side (the lower side in FIG. 1A) in the width direction Y of the plate 1. The notch 11 passes the excess toner scraped off when the elastic member 2 of the developing blade 10 is brought into contact with the developing roller to regulate the thickness of the toner supplied to the surface of the developing roller. It can function well as a discharge part.

As shown in FIG. 1A, the elastic member 2 is provided on the edge 1 a side on the surface of the plate 1, and the end 22 located on both ends in the longitudinal direction X, and between both ends 22 And a central portion 21 located at the center. The elastic member 2 has a notch 23 at a position corresponding to the notch 11 of the plate 1. Specifically, the elastic member 2 has a length in the longitudinal direction X at one end in the width direction of the end portion 22 (lower side in FIG. 1A) and adjacent to the central portion 21. It has a notch 23 that is shorter than the length in the longitudinal direction X.
In addition, as for the edge part 22, the length of the longitudinal direction X is 3 mm or more and 5 mm or less normally. Further, the central portion 21 generally has a length in the longitudinal direction X that is equal to or greater than the maximum width of an image that can be formed in the image forming apparatus using the developing blade 10. When the plate 1 has the cutout portion 11, the length in the longitudinal direction X of the central portion 21 is generally substantially equal to the distance along the longitudinal direction X between the cutout portions 11. Here, “substantially equal” indicates that the difference between the notch portions 11 and the distance along the longitudinal direction X is, for example, 1.0 mm or less.
As shown in the front view of the developing blade 10 in FIG. 1B, on one side in the width direction Y, the height of the central portion 21 and the height of the end portion 22 are the same.

Here, in the central portion 21 of the developing blade 10, a region 21A on at least one side in the width direction Y (the lower side in FIG. 1A) is formed using silicone resin. Specifically, in the central portion 21 of the developing blade 10, a region 21A on one side in the width direction is formed using silicone resin, and a region 21B on the other side in the width direction (upper side in FIG. 1A) It is formed using the same resin as the end 22 which will be described in detail later.
The silicone resin used for forming the region 21A is not particularly limited, and examples thereof include millable silicone and liquid silicone rubber.

The region 21 </ b> B on the other side in the width direction of the central portion 21 is connected to both end portions 22. That is, the region 21 </ b> B extends in the longitudinal direction X across the both end portions 22.
Further, as shown in FIG. 1 (c) a cross section taken along line I-I of FIG. 1 (a), the region 21B, the maximum height _{h 2} of the region 21B of region 21A which is formed by using a silicone resin maximum is formed to be lower than the height h _1.

Further, the end 22 of the developing blade 10 is formed using a resin having higher wear resistance than the silicone resin used for forming the region 21 </ b> A, and extends to the outside in the longitudinal direction from the notch 11 of the plate 1. It is extended.
The resin having higher wear resistance than the silicone resin is not particularly limited, and examples thereof include urethane resins such as two-component curable polyurethane and polyurethane-based thermoplastic rubber. Among them, from the viewpoint of excellent wear resistance, as a resin having higher wear resistance than a silicone resin, a resin having a wear amount of less than 0.85 g when a Taber wear test is conducted in accordance with JIS K7204. Preferably, non-foamed urethane resin is more preferable.

  The end 22 is integrally formed with the central portion 21. Specifically, the elastic member 2 including the central portion 21 and the end portion 22 is formed by using the known method such as two-color molding, for example, and forming the end portion 22 and the region 21B after forming the region 21A. Alternatively, the region 21A is formed after the end 22 and the region 21B are formed.

  The seal member 3 arbitrarily disposed on the plate 1 is a member for preventing the toner from leaking to the other side in the width direction. The seal member 3 is used in the field of the developing blade. Any known sealing member can be used.

  According to the developing blade 10 having the above-described configuration, the region 21A on the one side in the width direction of the central portion 21 is formed using silicone resin, so that one side in the width direction of the elastic member 2 contacts the developing roller. By controlling the toner layer thickness and triboelectric charging, the toner in contact with the central portion 21 can be charged satisfactorily. Further, in the developing blade 10, since the end portion 22 is formed using a resin having higher wear resistance than the silicone resin, the end portion 22 of the elastic member 2 that is particularly easily loaded when brought into contact with the developing roller. Can be prevented from being worn. Therefore, if the developing blade 10 is used, a good image can be formed over a long period of time. In addition, although the resin having higher wear resistance than the silicone resin that constitutes the end portion 22 generally has a lower charge imparting property to the toner than the silicone resin, as described above, the dimension in the longitudinal direction X of the central portion 21. Is usually larger than the maximum width of an image that can be formed in the image forming apparatus using the developing blade 10, the end 22 of the developing blade 10 may be made of a resin having higher wear resistance than silicone resin. As a result, a good image can be formed.

Further, in the developing blade 10, since the central portion 21 and the end portion 22 are integrally formed, the central portion 21 and the end portion 22 are compared with the case where the central portion 21 and the end portion 22 are separated. It is possible to prevent the toner from leaking out.
Further, in the developing blade 10, a region 21 </ b> B formed in the same resin as the end portion 22 (resin having higher wear resistance than the silicone resin) and connected to the end portion 22 exists in the central portion 21. Therefore, compared with the case where the region 21B does not exist in the central portion 21, the contact between the portion formed using the silicone resin and the portion formed using the resin having higher wear resistance than the silicone resin The area can be increased and the central portion 21 and the end portion 22 can be favorably bonded. Therefore, it is possible to prevent the central portion 21 and the end portion 22 that are integrated from being peeled off due to a load applied due to contact with the developing roller.
Further, in the developing blade 10, the region 21 </ b> B of the central portion 21 is formed using the same resin as the end portion 22 (resin having higher wear resistance than the silicone resin), and extends between both end portions 22. Since it extends, both the end portions 22 and the region 21B can be formed at a time. Therefore, both ends 22 are not connected via the region 21B, and the elastic member 2 can be easily formed as compared with the case where each end 22 needs to be formed separately.

Further, the developing blade 10, the maximum height h ₂ of the region 21B existing in the center portion 21 is less than the maximum height h ₁ of the region 21A, which is formed by using a silicone resin, region by contact with the developing roller Even when 21A is worn, it is possible to prevent the region 21B from coming into contact with the developing roller at an early stage. Therefore, it is possible to maintain the effect of charging the toner and forming a good image using the region 21A formed using the silicone resin over a long period of time.
From the viewpoint that region 21B due to wear of the region 21A is sufficiently prevented from contacting with the developing roller, the maximum height difference between _{h 2} of the maximum height _{h 1} and the region 21B of region 21A _(h 1 -h ₂ ) is preferably 0.01 mm or more. For the same reason, the dimension in the width direction Y of the region 21A is preferably 2.0 mm or more.
On the other hand, from the viewpoint of moldability, the difference between the maximum height _{h 2} of the maximum height _{h 1} and the region 21B of the region 21A _(h 1 -h ₂₎ is preferably 0.5mm or less. For the same reason, the dimension in the width direction Y of the region 21A is preferably 2.5 mm or less.

  Further, since the developing blade 10 is provided with the notches 11 and 23, when the toner layer thickness is regulated, excess toner can be scraped off and discharged. In general, when a notch is formed at the end of the elastic member, wear of the end is easily promoted by the toner staying in the notch, but the developing blade 10 is more resistant to abrasion than silicone resin. Since the end portion 22 is formed using a high resin, sufficient wear resistance can be ensured even when the notch portion 23 is formed in the end portion 22.

  The developing blade 10 having the above-described configuration is used in a developing unit 50 that constitutes a part of the image forming apparatus, as shown in FIG. In the image forming apparatus shown in FIG. 2 with only a part of the configuration, the electrostatic latent image is formed by attaching toner to the electrostatic latent image formed on the photosensitive drum 60 by a known method via the developing unit 50. Is visualized, and then the visualized image (toner image) is transferred to a recording medium (not shown) such as paper to form an image. 2 includes a toner box 52 that contains toner 51 as a developer, an agitator 53 that agitates the toner 51 in the toner box 52, and the toner 51 in the toner box 52 as a developing roller. The toner conveying roller 54 to be supplied to the surface of 55 and the developing blade 10 always urged so as to come into contact with the developing roller 55 are accommodated in a housing 56.

  More specifically, in the developing blade 10 having the above-described configuration, one side in the width direction of the elastic member 2 of the developing blade 10 contacts the developing roller 55, and the central portion 21 of the elastic member 2 is an image forming area. It is used by being installed in the housing 56 so as to be arranged at a position corresponding to.

  In the image forming apparatus having the developing unit 50, one side in the width direction of the central portion 21 arranged at a position corresponding to the image forming area is in contact with the developing roller 55, so that the toner is sufficiently charged and a good image is obtained. Can be formed. Further, the developing blade 10 is formed by using a resin having higher wear resistance than the silicone resin at the end portion 22 and is excellent in wear resistance. Therefore, the image forming apparatus having the developing unit 50 is good in the image forming apparatus. An image can be formed over a long period of time.

  As described above, the developing blade and the image forming apparatus using the developing blade of the present invention have been described using an example, but the present invention is not limited to the above example.

  Specifically, in the developing blade of the present invention, the central portion 21 and the end portion 22 of the elastic member 2 may not be integrally formed.

  Further, the region 21B connected to the end portion 22 exists only in a part of the central portion 21 as shown in FIG. 3A, and does not extend over the entire length of the central portion 21 in the longitudinal direction. Alternatively, as shown in FIG. 3B, it may not be present in the central portion 21 (that is, the central portion 21 may be formed using only a silicone resin). Furthermore, the region 21 </ b> B connected to the end portion 22 may extend only to a part of the central portion 21 in the height direction.

  Furthermore, as shown in FIG. 4, the end portion 22 may not extend to the outside in the longitudinal direction from the notch portion 11 of the plate 1. Specifically, for example, the end 22 may terminate in the longitudinal direction X at the same position as the outer end in the longitudinal direction of the notch 11. The developing blades 10C, 10D, and 10E shown in plan views in FIGS. 4A to 4C are different from those in FIGS. 1, 3A, and 3B except that the end positions of the end portions 22 are different. The developing blades 10, 10A, 10B shown in FIG.

  Further, as shown in FIG. 5, the plate 1 and the elastic member 2 may not have the notches 11 and 23.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these Examples.
In Examples and Comparative Examples, the evaluation of the wear resistance of the resin and the durability test were performed as follows.

<Abrasion resistance>
Based on JIS K7204, a Taber abrasion test was performed under the following conditions. And the amount of wear was measured. The smaller the amount of wear, the better the wear resistance.
[Measurements]
・ Abrasive paper: No. 100 (manufactured by Sumitomo 3M)
・ Rotation speed: 71rpm
・ Rotation speed: 2000 times ・ Load: 4.8N
<Durability test>
A developing blade was attached to an image forming apparatus having a developing unit having the configuration shown in FIG. 2, and 15,000 sheets of images were printed. The image quality, the presence or absence of toner leakage, and the state of the end of the developing blade were evaluated according to the following criteria.
[Image quality]
○: Density unevenness △: Density unevenness slightly, but no problem level ×: Density unevenness [toner leakage]
○: No leaking △: Slightly leaking but no problem level ×: Leaking [End state]
○: No dirt △: Slightly dirty but no problem level ×: Dirty

Example 1
A developing blade having the shape shown in FIG. 1 was prepared. In addition, as silicone resin which forms the area | region 21A of the center part 21, RBL-9200-60 (Abrasion amount: 0.85g) by Toray Dow Corning is used, Resin which forms the edge part 22 and the area | region 21B As for this, E580 (urethane resin, wear amount: 0.02 g) manufactured by Japan Miractolan Co., Ltd. was used. The maximum height of the region 21A was 1.50 mm, the dimension in the width direction Y of the region 21A was 2.3 mm, and the maximum height of the region 21B was 1.45 mm.
And the durability test was implemented. The results are shown in Table 1.

(Comparative Example 1)
The developing blade of Example 1 except that the elastic member 2 (both center and end) is formed only of silicone resin (RBL-9200-60 manufactured by Toray Dow Corning Co., wear amount: 0.85 g). A developing blade having the same configuration as in Example 1 was prepared.
And the durability test was implemented. The results are shown in Table 1.

(Comparative Example 2)
The elastic member 2 (both center and end) has the same configuration as that of the developing blade of Example 1 except that the elastic member 2 (both made by Nippon Milactolan, E580, wear amount: 0.02 g) is formed only. A developing blade was prepared.
And the durability test was implemented. The results are shown in Table 1.

  From Table 1, it can be seen that if the developing blade of Example 1 is used, a good image can be formed over a long period of time. On the other hand, with the developing blade of Comparative Example 1 having an elastic member made only of a silicone resin, a good image can be formed at the initial stage of printing, but since the abrasion resistance is low, a good image can be formed over a long period of time. I can't understand. In addition, it can be seen that with the developing blade of Comparative Example 2 provided with an elastic member made only of urethane resin, the toner cannot be sufficiently charged and a good image cannot be formed from the beginning of printing.

According to the present invention, it is possible to provide a developing blade that includes an elastic member that is excellent in both charge imparting property and abrasion resistance to toner and that can form a good image over a long period of time.
In addition, according to the present invention, it is possible to provide an image forming apparatus capable of forming a good image over a long period of time.

DESCRIPTION OF SYMBOLS 1 Plate 2 Elastic member 3 Seal member 10,10A, 10B, 10C, 10D, 10E, 10F Developing blade 11 Notch part 21 Center part 22 End part 23 Notch part 50 Developing unit 51 Toner 52 Toner box 53 Stirrer 54 Toner Conveying roller 55 Developing roller 56 Housing 60 Photosensitive drums 1a and 1b Edge 21A region 21B region

Claims (9)

A developing blade comprising a long plate and an elastic member disposed on the long plate along the longitudinal direction of the plate,
The elastic member includes an end portion located on each of both ends in the longitudinal direction, and a central portion located between both end portions,
The central portion is formed using at least one side in the width direction using a silicone resin,
The end portion is a developing blade formed using a resin having higher wear resistance than the silicone resin.   The developing blade according to claim 1, wherein the end portion and the central portion are integrally formed.   The developing blade according to claim 2, wherein the developing portion is formed using the resin having high wear resistance and has a region connected to at least one of the end portions in the central portion.   The developing blade according to claim 3, wherein the region extends between both ends.   The developing blade according to claim 3 or 4, wherein a maximum height of the region is lower than a maximum height of a portion formed using the silicone resin.   The developing blade according to claim 1, wherein the elastic member has a cutout portion at a position adjacent to the center portion on one side in the width direction of the end portion.   The developing blade according to claim 1, wherein the highly wear-resistant resin is a non-foamed urethane resin.   The developing blade according to claim 1, wherein seal members are disposed adjacent to both sides of the elastic member in the longitudinal direction. The developing blade according to any one of claims 1 to 8,
A developing roller in contact with the elastic member of the developing blade on one side in the width direction of the elastic member;
With
The image forming apparatus, wherein the central portion of the elastic member is disposed at a position corresponding to an image forming area.

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