JP2003140462A - Doctor blade for developing device, developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a doctor blade for a developing device by which even thin layer toner can be formed on a developing roll by smoothing out cracks and distortions unavoidably occurring in a manufacturing process. SOLUTION: In a blade substrate 11, a bending part 13 is provided and the bending part 13 is formed by bending one end of the blade substrate 11. A thin film layer 12 is provided on a surface of the blade substrate 11 on the opposite side to the bending direction of the bending part 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a doctor blade for a developing device, a developing device and an image forming apparatus. More specifically, it relates to improvement of a doctor blade used in an image forming apparatus such as an electronic copying machine, a laser beam printer, and a facsimile.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, a photoconductor as an image carrier is charged by a charger, and the photoconductor is irradiated with light according to image information to form a latent image. Then, the latent image is developed using a developing device, and the toner image on the photoconductor is transferred onto a sheet and fixed.

As described above, development is a process in which an electrostatic latent image formed on a photoconductor is visualized by toner in the image forming process, and dry development is generally adopted. Has been done. Dry development is roughly classified into a one-component development system and a two-component development system.

The two-component developing system is a developing system using a toner containing a carrier (magnetic powder such as iron powder and ferrite), and the one-component developing system is a developing system using a toner containing no carrier. .

A developing device of a one-component developing system (hereinafter referred to as a one-component developing device) has a simple structure as compared with a two-component developing system, and a toner density control device is not required, so that the cost is low. It is very advantageous for downsizing and downsizing. In reality,
Since a one-component developing device is becoming mainstream, centering on small printers and small copying machines, the following description will be made on the premise of the one-component developing device.

The one-component developing device includes a developing roller and a doctor blade for the developing device. The developing roller is a device that visualizes the electrostatic latent image formed on the photoconductor by the toner carried, and is rotatably supported inside the developing device. The doctor blade has an L-shaped bent portion at its tip. The bent portion is a reinforced portion which prevents the bending that occurs as the doctor blade is extended in the longitudinal direction and stabilizes the blade linear pressure between the doctor blade and the developing roller.

The toner adhering to the surface of the developing roller is conveyed to the contact portion between the developing roller and the doctor blade by the rotating operation of the developing roller. Then, the doctor blade having a stable blade linear pressure is used to reduce the film thickness, and the frictional force generated at the contact portion further carries an electric charge to increase the charge amount.

The toner whose charge amount is increased as described above is transferred and adhered from the developing roller to the photosensitive member due to the potential difference between the bias applied to the developing roller and the grounded photosensitive member. A visible image is formed.

By the way, in the conventional one-component developing apparatus, since the end portion of the blade base of the doctor blade is bent in an L shape, the end portion has a flatness such as cracks and strains due to the L-shaped bending. A uniform portion will inevitably occur.

As a result, the doctor blade includes a non-planar non-uniform portion at the contact portion with the developing roller that rotates, so that the linear pressure of the blade becomes unstable and the developing roller is in a non-uniform state.
However, there is a problem in that the toner on the toner cannot always be thinned uniformly and uneven density occurs on the printed image.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to form a uniform thinned toner on a developing roller and prevent the occurrence of uneven density, a doctor blade for a developing device, a developing device and an image forming apparatus. Is to provide.

Another object of the present invention is to provide a doctor blade for a developing device, a developing device and an image forming apparatus for smoothing non-uniformity of flatness such as cracks and strains inevitably generated in the manufacturing process. is there.

[0013]

In order to solve the above problems, a doctor blade for a developing device according to the present invention includes a blade base and a thin film layer. The blade substrate is
It has a bent portion. The bent portion is formed by bending an end portion of the blade base. The thin film layer is provided on the surface of the blade base on the side opposite to the bending direction of the bent portion.

As described above, the doctor blade for the developing device according to the present invention includes the blade base. The blade base has a bent portion. The bent portion is formed by bending the end portion of the blade base. According to the above structure,
When applied to a developing device, the doctor blade can be prevented from bending in the longitudinal direction, and the blade linear pressure to the developing roller can be stabilized. By stabilizing the blade linear pressure on the developing roller, a uniform thin toner can be formed on the developing roller. Further, according to the above-mentioned structure, the frictional force generated by the contact can be used to maintain or improve the charging efficiency of the toner on the developing roller.

Moreover, the bending structure of the end portion of the blade base body is an effective structure for securing the mechanical strength of the blade base body and preventing the occurrence of bending, and at the same time, is a simple and simple structure, so that it is relatively easy to implement. .

By providing the bent portion on the blade substrate, the above-mentioned advantages can be obtained. However, in the periphery of the bent portion, non-uniformity in planarity such as cracks and strains is generated due to the formation of the bending structure. To do. If the contact surface includes a non-uniformity in flatness, instability of the linear pressure of the blade is induced, so that the toner on the developing roller cannot be uniformly thinned and uneven density is likely to occur. As described above, the problem occurs.

As a means for solving the above problems, the doctor blade for a developing device according to the present invention includes a thin film layer. The thin film layer is provided on the surface of the blade base on the side opposite to the bending direction of the bent portion. According to the above structure, the flatness non-uniformity portion which is inevitably generated by bending can be supplemented by the thin film layer and smoothed. Further, the surface accuracy of the contact portion between the blade substrate and the developing roller can be improved. Therefore, according to the doctor blade for a developing device of the present invention, it is possible to form a uniform thinned toner on the developing roller and prevent uneven density.

The present invention also discloses a developing device, an image forming apparatus and a method for manufacturing a doctor blade, which uses the doctor blade described above.

Other objects, structures and advantages of the present invention will be described in more detail with reference to the accompanying drawings. The accompanying drawings are merely illustrative of the embodiments.

[0020]

1 is a perspective view of a doctor blade for a developing device according to the present invention, and FIG. 2 is a sectional view taken along line 2-2 shown in FIG. The illustrated doctor blade for a developing device includes a blade substrate 11 and a thin film layer 12.

The blade substrate 11 has a bent portion 13. The bent portion 13 is formed by bending the end portion of the blade base 11. The bent portion 13 is formed by bending a predetermined end portion of the blade base 11 over the entire length in the longitudinal direction with a uniform width at an angle of approximately 90 degrees. However, since the bending angle of the bending portion 13 is merely an example, it may be bent at 90 degrees or more or 90 degrees or less, or may be completely folded. Blade base 11
Is made of a flat metal material including stainless steel, phosphor bronze, and the like. The blade substrate 11 shown in the figure has a plurality of supporting portions 14. The support portion 14 is a connecting portion when the doctor blade for the developing device is incorporated in the developing device, and is formed as a hole. However, since the support portion 14 follows the coupling means included in the developing device, the support portion 14 is not limited to a hole, and may have, for example, an uneven shape or may be omitted.

The thin film layer 12 is provided on the surface of the blade base 11 on the side opposite to the bending direction of the bent portion 13. The thin film layer 12 shown is a blade substrate 1
The surface of No. 1 is fitted over the entire length in the longitudinal direction. The thin film layer 12 is made of plastic, rubber, sponge, or the like.

FIG. 3 is a sectional view of a one-component developing device which is a part of the image forming apparatus using the doctor blade for the developing device according to the present invention. The developing device shown in FIG. 3 includes a doctor blade 1, a developing container 2, a toner 3, a toner stirring member 4, a toner replenishing roller 5, a developing roller 6, a photosensitive drum 7, and a developing device doctor blade holding portion. Including 9.
The doctor blade 1 is the doctor blade for a developing device according to the present invention shown in FIGS. 1 and 2.

The developing container 2 has an opening at least at one end, and the toner 3 is supplied into the developing container 2. Both ends of the toner agitating member 4 are rotatably supported in the developing container 2 to prevent the toner 3 from aggregating by the rotating operation in the direction indicated by the arrow a, and to convey the toner 3 to the toner replenishing roller 5. To do.

The toner 3 is conveyed by the toner stirring member 4 and enters the toner replenishing roller 5, which is generally spongy. Both ends of the toner replenishing roller 5 are rotatably supported in the developing container 2 similarly to the toner stirring member 4.

The toner 3 is carried by the toner replenishing roller 5 rotating in the direction indicated by the arrow b to the contact rotating portion between the toner replenishing roller 5 and the developing roller 6. Then, in the contact rotating portion, the toner 3 is charged by the frictional force caused by the sliding of the developing roller 6 and the toner replenishing roller 5, and electrostatically adheres to the surface of the developing roller 6.

The developing roller 6 is a device for carrying the toner 3 and for visualizing the electrostatic latent image formed on the photosensitive drum 7 by the toner 3, and the toner replenishing roller 5 and the toner replenishing roller 5. Similarly, it is rotatably supported inside the developing container 2. The toner 3 attached to the surface of the developing roller 6 is conveyed to the contact portion with the doctor blade 1 on the developing roller 6 rotating in the direction indicated by the arrow c.

The doctor blade 1 is sandwiched and fixed by a doctor blade holding portion 9 for a developing device, which is composed of two rigid metal plates.

Further, the doctor blade 1 is a developing roller.
The roller 6 faces and abuts against the roller 6 in the rotational direction indicated by the arrow c. Therefore, the toner 3 adhered on the developing roller 6 is uniformly thinned by the rotational operation thereof, and the frictional force is reduced. To increase the charge amount of the toner 3. The toner 3 having the increased charge amount is transferred from the developing roller 6 to the photoconductor drum 7 due to the potential difference between the bias applied to the developing roller 6 and the grounded photoconductor drum 7, and the electrostatic latent image is transferred. The photosensitive drum 7 on which the image is formed is visualized by the toner 3.

Here, the doctor blade 1 is the doctor blade for the developing device according to the present invention shown in FIGS. 1 and 2, and includes a blade base 11. Blade base 11
Has a bent portion 13. The bent portion 13 is formed by bending the end portion of the blade base 11. According to the above-mentioned structure, when applied to the developing device, the bending that occurs in the longitudinal direction of the doctor blade 1 is prevented, and the developing roller is prevented.
It is possible to stabilize the blade linear pressure on the blade 6. Then, the blade linear pressure on the developing roller 6 is stabilized, so that a uniform thinned toner can be formed on the developing roller 6. Further, according to the above-described structure, the frictional force generated by the contact can be utilized to favorably maintain or improve the charging efficiency for the toner on the developing roller 6.

Moreover, the structure in which the end portion of the blade base body 11 is bent is an effective structure for securing the mechanical strength of the blade base body 11 and preventing the occurrence of bending, and at the same time, it is a simple and simple structure, so that it is relatively implemented. It's easy.

By providing the bent portion 13 on the blade base 11, the above-described advantages can be obtained. However, in the periphery of the bent portion 13, unevenness in planarity such as cracks and strains is caused due to the bending structure. A part occurs. If the contact surface includes a non-planar uneven portion, the blade linear pressure becomes unstable, so that the toner on the developing roller 6 cannot always be uniformly thinned and uneven density tends to occur. The generation of dots is as described above.

As a means for solving the above problems, the doctor blade 1 for a developing device according to the present invention includes a thin film layer 12. The thin film layer 12 is provided on the surface of the blade base 11 on the side opposite to the bending direction of the bent portion 13. According to the above-mentioned structure, the flatness nonuniformity part which is inevitably generated by bending can be supplemented by the thin film layer 12 and smoothed. Further, the surface accuracy of the contact portion between the blade substrate 11 and the developing roller 6 can be improved. Therefore, according to the doctor blade for the developing device of the present invention, the developing roller
It is possible to form a uniform thinned toner on the toner layer 6 and prevent uneven density.

Moreover, since a flat metal material is used for the blade base 11, the mechanical strength which is the basis of the doctor blade, the ease of manufacturing and processing, and the harmonization point between the two can be set in advance by selecting the metal material.

FIG. 4 is a perspective view showing a manufacturing process of the doctor blade according to the present invention, and FIG. 5 is a perspective view showing a process subsequent to the thinning process shown in FIG.

First, as shown in FIG. 4, the blade substrate 1
A thin film layer forming material 12 to be a thin film layer is mounted on a predetermined surface of 1. The thin film layer forming material 12 is a thin film sheet.

Next, the rolling roller 8 is moved in the direction indicated by the arrow X while being rotated in the direction indicated by the arrow Y, and the pressing force indicated by the arrow Z is applied to the thin film layer forming material 12. Thus, the air remaining between the thin film sheet and the doctor blade base 11 is pushed out. As a result, the thin film sheet is in close contact with and fixed to the blade substrate 11. The pressing force of the pressure roller 8 is preferably in the range of 0.1 to 12.5 N · cm. Within this range, the thin film layer forming material 12 made of a thin film sheet can be adhered and adhered to the blade substrate 11 without causing distortion or deformation.

FIG. 6 is a perspective view showing another embodiment of the thin film layer forming step. In FIG. 6, a thin film layer forming material 12 to be a thin film layer is applied to the bent portion 13 of the doctor blade. The thin film layer forming material 12 is a coating material.

Next, in the heat-drying treatment step, the rolling roller 8 is rotated in the direction indicated by the arrow Y while the arrow X is being rotated.
And is applied in the direction indicated by an arrow Z to the thin film layer forming material 12 made of a coating material. The pressing force of the pressure roller 8 is preferably in the range of 0.1 to 12.5 N · cm. Within this range, the applied thin film layer 12 can be evenly fixed without giving distortion or deformation to the blade substrate 11. As a result, the coating unevenness of the thin film layer forming material 12 made of a coating material is removed, and the thin film layer 12 having excellent surface smoothness is formed.

[0040]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a doctor blade for a developing device, a developing device, and an image forming apparatus capable of forming a uniform thinned toner on a developing roller and preventing uneven density. (B) It is possible to provide a doctor blade for a developing device, a developing device, and an image forming apparatus that smooth a flatness nonuniformity portion such as cracks and strains inevitably generated in the manufacturing process.

[Brief description of drawings]

FIG. 1 is a perspective view of a doctor blade for a developing device according to the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view of a developing device that is a part of an image forming apparatus including a doctor blade according to the present invention.

FIG. 4 is a perspective view showing a starting state in a manufacturing process of a doctor blade for a developing device according to the present invention.

5 is a perspective view showing a final step of the step shown in FIG. 4. FIG.

FIG. 6 is a perspective view showing another manufacturing process of the doctor blade for the developing device according to the present invention.

[Explanation of symbols]

11 Blade base 12 thin film layers 13 Bent section 14 Support

Claims (4)

[Claims] 1. A doctor blade for a developing device, comprising a blade base and a thin film layer, wherein the blade base has a bent portion, and the bent portion is formed by bending an end portion of the blade base. A doctor blade for a developing device, wherein the thin film layer is provided on the surface of the blade base on the side opposite to the bending direction of the bending portion. 2. A developing device including a developing roller and a doctor blade for the developing device, wherein the doctor blade for the developing device is the one described in claim 1, wherein the thin film layer is A developing device that contacts the surface of the developing roller. 3. An image forming apparatus having a developing device, wherein the developing device is the one described in claim 2. 4. A method of manufacturing a doctor blade for a developing device, wherein the doctor blade for the developing device is the one described in claim 1, wherein a thin film layer forming material is mounted on a predetermined surface of the blade substrate. Then, a method of manufacturing a doctor blade for a developing device, comprising the step of pressing the thin film layer forming material with a roller to fix the material.