JPH09222793A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain an excellent image without a white streaky noise, density unevenness, etc., by performing electroless nickel plating on the surface of a regulating member. SOLUTION: As the regulating member 12, a stainless steel plate is used, the end part coming into contact with a toner carrier of the plate is bent and then, the surface has the electroless nickel plating 12a. Then, the regulating member 12 is brought into press-contact with the surface of the toner carrier. Thus, when the surface of the regulating member 12 brought into press-contact with the surface of the toner carrier has the electroless nickel plating 12a, the surface of the regulating member 12 is made smooth. Especially, in the case the end part of the regulating member 12 brought into press-contact with the surface of the toner carrier is bent in the axial direction of the toner carrier, even if the bent part of the regulating member 12 is cracked, the crack does not become large by the sticking of the toner to the surface of the regulating member 12, because the surface of the bent part is smoothened by the electroless nickel plating 12a.

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 an image forming apparatus such as a copying machine and a printer, and more particularly to a one-component developing system using only toner as a developer. The plate-shaped regulating member is brought into pressure contact with the surface of the toner carrier for conveying the toner to the image carrier, and the toner supplied to the surface of the toner carrier is frictionally charged by the regulating member and the amount of toner on the surface of the toner carrier is The present invention relates to a developing device that regulates the above.

[0002]

2. Description of the Related Art Conventionally, as a developing device used in an image forming apparatus such as a copying machine or a printer, a two-component developing system in which a toner and a carrier are used as a developer, and a developing device without a carrier are used. A one-component developing system using only toner is known.

In the case of a two-component developing system, the carrier and toner are generally mixed and stirred in the main body of the apparatus to charge the toner, and the developer thus charged with the toner is magnetized inside. The developer is supplied to a developer carrying member provided with a roller, and the developer is carried by the developer carrying member to a developing area facing the image carrier to develop the electrostatic latent image formed on the image carrier. It was.

However, in the case of the two-component developing system as described above, a mechanism for mixing and stirring the toner and the carrier is required, which causes a problem that the device becomes large and the cost becomes high.

Further, in the case of the above-described two-component developing system developing device, the toner is mixed with the carrier and stirred so that the toner is charged. Part adheres to the carrier,
As a result, the carrier is spent, the charging performance of the carrier with respect to the toner is deteriorated, and there is a problem in that the charge amount of the toner is changed.
Since the carrier is repeatedly used for triboelectrification of the toner, the carrier gradually becomes spent and deteriorates, which gradually reduces the charge amount of the toner, resulting in fogging of the formed image and development of the toner. There is a problem that the image forming apparatus is scattered from the apparatus and the inside of the image forming apparatus is soiled.

For this reason, in recent years, a developing device of a one-component developing system in which only a toner is used without using a carrier has attracted attention.

Here, as such a one-component developing system, a developing device disclosed in Japanese Patent Laid-Open No. 52-143831 is generally used. As shown in FIG. 1, toner is carried on an image. A regulating member 1 formed on the surface of the toner carrier 11 conveyed to the body 1 in a plate shape of stainless steel or the like.
2'is pressed, and the toner supplied to the surface of the toner carrier 11 is frictionally charged by the regulating member 12 ', and the amount of toner on the surface of the toner carrier 11 is regulated.

However, when the plate-shaped regulating member 12 'is brought into contact with the surface of the toner carrier 11 as described above, FIG.
If a flat plate-shaped member is used as the regulating member 12 ′, the regulating member 12 ′ will be attached to the toner carrier 11 as shown in FIG.
It was very difficult to make a stable contact with the surface at an appropriate pressure in the axial direction of.

For this reason, the toner supplied to the surface of the toner carrier 11 cannot be properly triboelectrically charged, and the amount of the toner conveyed to the image carrier 1 becomes low, resulting in an image to be formed. Fogging occurs, or conversely, the toner charge amount becomes too high, so that the toner is not properly supplied to the image bearing member 1 and the density of the formed image is lowered, and the toner bearing member 11 is caused. There is a problem in that the amount of toner on the surface of the sheet cannot be properly regulated, and the amount of toner conveyed to the image carrier 1 changes, resulting in uneven density in the formed image.

Further, as described above, when the regulating member 12 'is pressed against the surface of the toner carrier 11 to regulate the amount of toner and the toner is frictionally charged, the regulating member 1 is used.
Toner may adhere to the surface of the toner carrier 2'and grow, which causes unevenness in the thickness of the toner on the surface of the toner carrier 11, resulting in white stripe noise in the formed image and uneven density. There were problems such as occurrence.

Therefore, in recent years, FIG. 2 and FIG.
As shown in (A) and (B), at the end portion where the plate-shaped regulating member 12 ′ comes into contact with the toner carrier 11, the regulating member 12 ′ is moved in the axial direction of the toner carrier 11. The strength of the regulating member 12 'is increased by bending the regulating member 12' along the axial direction so that the regulating member 12 'can be stably brought into contact with the surface of the toner carrier 11 in the axial direction at an appropriate pressure. It was

However, when the plate-shaped regulating member 12 'made of stainless steel or the like is bent, a crack is generated in the regulating member 12' at the bent portion.
When the regulating member 12 'is pressed against the surface of the toner carrier 11 to regulate the amount of toner and the toner is triboelectrically charged, a large amount of toner adheres to the cracks and grows. When the amount of toner on the surface of the toner carrier 11 is regulated by 12 ', the thickness of the toner on the surface of the toner carrier 11 becomes uneven as in the above case, and white streak-like noise appears in the formed image. There are problems such as occurrence of unevenness and uneven density.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a plate-shaped regulating member is brought into pressure contact with the surface of a toner carrier for conveying toner to an image carrier, and the toner supplied to the surface of the toner carrier by this regulating member. It is an object of the present invention to solve the above-mentioned various problems in the developing device in which the toner is triboelectrically charged and the amount of toner on the surface of the toner carrier is regulated.

That is, according to the present invention, in the developing device as described above, a plate-shaped regulating member is brought into pressure contact with the surface of the toner carrying member which conveys the toner to the image bearing member, and the regulating member causes the toner carrying member to move. When the toner supplied to the surface is triboelectrically charged and the amount of toner on the surface of the toner carrier is regulated, the toner adheres to the regulation member and the thickness of the toner conveyed by the toner carrier becomes uneven. It is an object of the present invention to stably obtain a good image without white stripe noise and density unevenness.

[0015]

According to the present invention, in order to solve the above-mentioned problems, a plate-shaped regulating member is brought into pressure contact with the surface of the toner carrying member which conveys toner to the image carrying member, and the regulating member. In the developing device in which the toner supplied to the surface of the toner carrier is triboelectrically charged and the amount of toner on the surface of the toner carrier is regulated, electroless nickel plating is applied to the surface of the regulation member. is there.

Here, like the developing device of the present invention, when electroless nickel plating is applied to the surface of the regulating member which is brought into pressure contact with the surface of the toner carrying member, the surface of the regulating member becomes smooth, and in particular, the toner carrying member is carried. When the end of the regulating member that is brought into pressure contact with the surface of the body is bent along the axial direction of the toner carrier as described above, even if cracks occur in the folded portion of the regulating member, the surface of the folded portion is Smoothed by electroless nickel plating,
The toner does not adhere to the surface of the regulation member and grow unlike the conventional case.

Therefore, when the regulating member is pressed against the surface of the toner carrier to frictionally charge the toner on the surface of the toner carrier and to regulate the amount of toner on the surface of the toner carrier, the toner carrier is The toner on the surface of the toner is prevented from adhering to the regulation member, the thickness of the toner on the surface of the toner carrier does not become non-uniform, and white streak-like noise or density unevenness occurs in the formed image. Will not occur.
Further, it becomes possible to charge the toner on the surface of the toner carrier in a constant state, the charge of the toner becomes stable, and the amount of charge of the toner conveyed to the image carrier becomes low, so that an image to be formed is formed. It is less likely that the density of the formed image will be lowered due to fogging or, on the contrary, the toner charge amount becoming too high.

Here, in performing electroless nickel plating on the surface of the regulating member as described above, nickel plating is performed so that the surface of the regulating member is stably and smoothly maintained by the nickel plating. Is 0.5 to 30 μm, preferably 1 to 15 μm.

Further, in the developing device of the present invention, as the toner which is supplied to the surface of the toner carrier as described above and frictionally charged by the regulating member, a commonly used known toner can be used. Such a toner contains at least a binder resin and a colorant.

Here, as the binder resin used in this toner, a known resin that has been generally used in the past can be used, and from the viewpoint of enhancing the storage stability and fixing property of the toner, the glass transition point is used. Tg is 55-75
A resin having a softening point of 80 to 170 ° C., preferably 90 to 150 ° C. is used. Further, from the viewpoint of improving the dispersibility of the colorant and the offset preventing agent added to the toner and improving the environmental stability of the toner,
It is preferable to use a resin having an acid value in the range of 10 to 40 KOHmg / g, and in view of toner productivity, the melt index MI value is 3 to 20 (150 ° C. /
min) is preferably used, and for example, polyester resin or urethane modified polyester resin is preferably used. However, the binder resin used for the toner is not particularly limited to these resins.

The colorant used in this toner may also be a known colorant that has been generally used in the past. For example, in the case of a black toner, carbon black, copper oxide, manganese dioxide are used. , Aniline black, activated carbon, etc. can be used alone or in combination of two or more kinds, and in the case of full-color toner, various known yellow pigments, red pigments, and blue pigments can be used depending on the color of the toner. Pigments can be used. The amount of these colorants added to the toner is such that the colorant is in the range of 1 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the binder resin in the toner. To do.

The toner used in the present invention includes, in addition to the binder resin and the colorant as described above, a charge control agent, an offset preventive agent, a fluidizing agent and the like which are generally used in the toner, if necessary. Is added in an appropriate amount.

The toner used in the present invention preferably has a volume average particle diameter of 5 to 9 μm. When the volume average particle size is larger than 9 μm, the reproducibility of high-definition images deteriorates,
This is because when the volume average particle diameter is smaller than 5 μm, the productivity of the toner deteriorates.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings, and a good image can be stably obtained when an image is formed in the developing device of this embodiment. Make clear.

Here, in the developing device in this embodiment, as shown in FIG. 4, the toner 2 is accommodated in the toner accommodating portion 13 in the apparatus main body 10, and the toner provided in the toner accommodating portion 13 is accommodated. The feeding member 14 is rotated to feed the toner stored in the toner storage portion 13 to the toner supply portion 15 on the toner carrier 11 side.

The toner 2 thus fed to the toner supply unit 15 is supplied to the surface of the toner carrier 11 by the toner supply member 16.

Here, in this developing device, a thin sleeve-shaped member having a diameter larger than that of the driving roller 17 is used as the toner carrier 11. The toner carrier 11 is made of nylon and has a surface roughness Rz
Is about 5 μm and the electric resistance is 10 ⁴ Ω · cm.

Then, the toner carrier 11 is arranged so as to cover the outer periphery of the driving roller 17, and the toner carrier 11 is disposed inside the apparatus main body 10 on the side opposite to the developing section facing the image carrier 1. This toner carrier 11
Guide members 18 are provided on both axial ends of the toner carrier 11 by the guide members 18.
The toner carrier 11 is brought into pressure contact with the drive roller 1
The toner carrier 11 is rotated at the developing unit facing the image carrier 1 while rotating the toner carrier 11.
Is projected toward the image carrier 1 side from the drive roller 17, and the toner carrier 11 thus projected is brought into soft contact with the surface of the image carrier 1.

Further, in this developing device, at the stage of introducing the toner 2 supplied to the toner carrier 11 as described above to the developing section facing the image carrier 1, the toner carrier 11 is plate-shaped. The end portion contacting with the toner carrier 1
A regulating member 12 bent in a direction away from the toner carrier 11 in the axial direction of 1 is brought into pressure contact with the surface of the toner carrier 11, and the toner 2 supplied to the toner carrier 11 is frictionally charged by the regulating member 12. At the same time, the amount of toner 2 on the toner carrier 11 is regulated.

Here, in the developing device of this embodiment, a stainless steel plate material made of a SUS301 steel plate having a thickness of about 0.1 mm is used as the regulating member 12.
After bending the end portion of the plate member that comes into contact with the toner carrier 11 as described above, a film thickness of about 5 is formed on the surface of the plate member.
The electroless nickel plating 12a having a thickness of μm is used, and the regulating member 12 is pressed against the surface of the toner carrier 11 with a pressing force of 7 g / mm.

On the other hand, in the toner 2 used in this developing device, the binder resin has a glass transition point T.
g is 65 ° C, softening point Tm is 140 ° C, acid value is 25KOH
mg / g, melt index MI value of 3.6 (150
(° C / 10 min) polyester resin was used. Then, carbon black (made by Colombian Carbon Co .: Ra
ven1255), 4 parts by weight, a charge control agent (Orient Chemical Co., Ltd .: S-34) 3 parts by weight, oxidized low molecular weight polypropylene (Sanyo Chemical Co., Ltd .: Viscor TS-200).
Was added at a ratio of 2.5 parts by weight, and they were thoroughly mixed with a Henschel mixer, then they were kneaded using a twin-screw extrusion kneader, and the kneaded product was left to cool and then coarsely pulverized using a feather mill. Then, finely pulverized with a jet mill and subjected to air classification to obtain toner particles having a volume average particle size of 8.0 μm. Then, hydrophobic silica (H-2000 manufactured by Hoechst Co.) is added to the toner particles. 0.5 wt% was added and mixed and stirred by a Henschel mixer, and the toner 2 having the surface treated with hydrophobic silica was used.

Next, using the developing apparatus of this embodiment, an image having a black ratio (B / W ratio) of 4% was printed at a speed of 6 sheets per minute to evaluate the formed image. Then, the adhesion state of the toner 2 to the regulation member 12 was examined.

As a result, in the developing device of this embodiment, even when 10,000 images were formed, white streak-like noise, fog, density decrease, density unevenness and the like were generated in the formed image. And a good image is obtained,
Regarding the adhesion of the toner 2 to the regulation member 12,
Adhesion of Toner 2 was hardly found by observation with a metallographic microscope.

Next, only the regulating member 12 in the developing device of this embodiment is changed, and as shown in FIGS. 3A and 3B, the conventional regulating member 12 whose surface is not nickel-plated. ', The image is formed in the same manner as in the above case, and the formed image is evaluated and regulated member 1
The adhesion state of Toner 2 on 2'was examined.

As a result, when the regulation member 12 'which is not plated with nickel is used, the image density in the solid black portion is lowered by the formation of 4000 images, and the density unevenness and white stripe noise are generated. It was confirmed that the toner 2 was conspicuously adhered to the regulation member 12 ', and the charge amount of the toner 2 was reduced by about 40% from the initial amount.

[0036]

As described above in detail, in the developing device of the present invention, the surface of the regulating member which is brought into pressure contact with the surface of the toner carrier is electroless nickel plated.
The surface of the regulating member becomes smooth, and in particular, when the end portion of the regulating member brought into pressure contact with the surface of the toner carrier is bent along the axial direction of the toner carrier as described above,
Even if cracks occur in the bent portion of the regulating member, the surface of the bent portion is smoothed by electroless nickel plating, and toner does not adhere to the surface of the regulating member and grow unlike the conventional case. It was

As a result, in the developing device of the present invention,
When the regulating member is brought into pressure contact with the surface of the toner carrier to frictionally charge the toner on the surface of the toner carrier and regulate the amount of toner on the surface of the toner carrier, the toner on the surface of the toner carrier is Adhesion to the regulation member is suppressed, and the thickness of the toner on the surface of the toner carrier is not uneven,
As a result, it is possible to suppress the occurrence of white stripe noise and density unevenness in the formed image, and it is possible to charge the toner on the surface of the toner carrier in a constant state. It is less likely that fog will occur and the density of the formed image will decrease, and good images can be stably obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a state in which a plate-shaped regulating member is pressed against the surface of a toner carrier in a conventional developing device.

FIG. 2 is a view showing a conventional developing device in which an end portion of a plate-shaped regulating member that comes into contact with a toner carrier is bent along the axial direction of the toner carrier, and the regulating member is placed on the surface of the toner carrier. FIG. 3 is a schematic explanatory view showing a state in which it is pressed against.

3A and 3B are a perspective view and a partially enlarged explanatory view of a conventional regulating member in which an end portion on a side in contact with a toner carrier is slightly bent along an axial direction of the toner carrier.

FIG. 4 is a schematic explanatory diagram of a developing device according to an embodiment of the present invention.

5A and 5B are a perspective view and a partially enlarged explanatory view of a regulating member used in the developing device of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Toner 11 Toner carrier 12 Regulation member 12a Nickel plating

Front Page Continuation (72) Inventor Ryuji Furumoto 2-3-13 Azuchi-cho, Chuo-ku, Osaka Osaka International Building Minolta Co., Ltd. (72) Inventor Shuichi Nakagawa 2-3-3 Azuchi-cho, Chuo-ku, Osaka Osaka International Building Minolta Co., Ltd.

Claims (1)

[Claims] 1. A plate-shaped regulating member is brought into pressure contact with the surface of the toner carrying member that conveys the toner to the image bearing member, and the toner supplied to the surface of the toner carrying member is frictionally charged by the regulating member and the toner carrying member is also formed. In a developing device configured to regulate the amount of toner on the surface of the developing device, a developing device characterized in that the surface of the regulating member is plated with electroless nickel.