JP3458645B2 - Developer carrier and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an electrophotographic image forming apparatus such as a copying machine or a printer, and develops an electrostatic latent image formed on a latent image carrier such as a photosensitive drum. More specifically, the present invention relates to a developer carrier used for supplying a developer and a method for manufacturing the same, and more specifically, it comprises a cylindrical developing sleeve and a magnetic force generating means arranged inside the cylinder of the developing sleeve. And a method for manufacturing the same, which holds the developer on the surface of the developing sleeve by the magnetic force of 1 and conveys the held developer by the rotation of the developing sleeve.

[0002]

2. Description of the Related Art An electrophotographic image forming apparatus forms an electrostatic latent image having a potential distribution corresponding to image information on a latent image carrier such as a photoconductor drum and charges the electrostatic latent image. An image is formed by developing with toner and then transferring and fixing the toner image formed by the development onto a transfer material such as paper. In an apparatus that forms an image by such a method, generally, a developing sleeve is provided with a developer carrying member including a cylindrical developing sleeve and a magnetic force generating means arranged inside the cylinder of the developing sleeve. It is arranged so as to face the latent image carrier at a minute interval. As a result, the developer carrying member holds the developer on the surface of the developing sleeve by the magnetic force of the magnetic force generating means and conveys the held developer by the rotation of the developing sleeve to the latent image carrying member. By supplying a developer, the electrostatic latent image on the latent image carrier can be developed with toner. In addition,
Hereinafter, the distance between the developing sleeve and the latent image carrier is also referred to as a developing gap.

As described above, in the structure in which the electrostatic latent image is developed by supplying the developer to the latent image carrier, a certain amount or more of the developer is stably supplied to the latent image carrier. Continuing to stabilize the development density by the toner, which in turn stabilizes the quality of the image formed on the paper.

Therefore, in order to secure the amount of developer conveyed by the developer carrying member, a plurality of recesses are formed in the developing sleeve by arranging them in the rotational direction of the developing sleeve (Japanese Patent Laid-Open No. 4-240880). ), A recess is formed in the developing sleeve along the direction of rotation of the developing sleeve (Japanese Patent Laid-Open No. Sho 5).
A technique for forming a plurality of grooves on the outer peripheral surface of the developing sleeve has been conventionally proposed by referring to JP-A 7-62076). In this way, when the groove is formed on the surface of the developing sleeve, the developer can be held and conveyed also in the groove, so that the conveying amount of the developer can be improved.

[0005]

However, the developing sleeve is required to have a high accuracy in terms of the accuracy of the developing gap, and moreover, 300 to 4 for a diameter of about several tens of mm.
Since it is generally formed in a cylindrical shape having a length of 00 mm, it is generally formed by using a metal material such as stainless steel, which is relatively easy to secure rigidity. Therefore, the recesses disclosed in these publications are usually formed by milling on the outer peripheral surface of a cylindrical pipe material that serves as a developing sleeve. Specifically, the method of forming the recesses by milling is such that the rotating cutting teeth are brought into contact with the outer peripheral surface of the cylindrical pipe material, and the cutting teeth are moved in the cylindrical axial direction in that state to form the recesses. This is a method of forming one by one.

Further, in the conventional developing sleeve having the recess formed by such milling, there is a problem that the tube material is bent or crushed during processing, so that the accuracy of cylindricity is deteriorated. . If the cylindricity is deteriorated in this way, for example, the developing gap between the latent image carrier and the developing sleeve may not be uniform in the axial direction of the developing sleeve, or the developing gap may vary due to the rotation of the developing sleeve. Therefore, density unevenness and the like depending on the rotation pitch of the developing sleeve will occur in the image. By the way, the diameter is 20mmφ or less and the wall thickness is 1
mm pipe material, for example, length 300 mm, outer diameter 18 mm,
In a developing sleeve in which a plurality of recesses are formed by milling a pipe material having a wall thickness of 1 mm, when the developing sleeve is rotated once with the probe contacting the outer peripheral surface of the pipe material, the peripheral surface other than the recesses The deflection width of the portion in the direction perpendicular to the contact surface of the meter reading exceeded 50 μm, resulting in uneven density.

Therefore, according to the present invention, it is possible to secure a transport amount of the developer above a certain level without extremely deteriorating the cylindricity of the developing sleeve. An object of the present invention is to provide a developer carrying member which does not cause uneven density even in a sleeve, and a manufacturing method thereof.

[0008]

That is, in order to solve the above-mentioned problems, the first invention of the present application is provided with a cylindrical developing sleeve (1) and a cylindrical developing sleeve (1). And a magnetic force generating means (2) for holding the developer on the surface of the developing sleeve (1) by the magnetic force of the magnetic force generating means (2) and at the same time the developer held by the rotation of the developing sleeve (1). Developer carrier to be conveyed (3)
The developing sleeve (1) has a plurality of grooves arranged on the outer peripheral surface of the cylindrical tube member (13) in the rotational direction of the developing sleeve (1) and extending along the longitudinal direction of the tube member.
A plurality of concave portions (1a) for forming the above, and a plurality of convex portions (1b) projecting outward from the outer peripheral surface are formed in a portion adjacent to each concave portion.

Further, in the developing sleeve having such a shape, as compared with the developing sleeve in which the concave portion is simply formed on the outer peripheral surface of the pipe material, the convex portion protruding outward from the outer peripheral surface of the pipe material is formed in the portion adjacent to the concave portion. Since the depth of the groove can be improved, on the other hand, compared with the case where the groove of the same depth is formed only by the concave portion, the thickness of the developing sleeve is reduced to reduce the magnetic force generating means from the surface of the developing sleeve. Since it is possible to shorten the distance to, it is possible to improve the carrying amount of the developer while reducing the diameter of the developing sleeve.

Further, in the case of the developing sleeve having such a shape, a cylindrical pipe material is press-fitted into a molding hole having a shape in which a plurality of protrusions and a plurality of recesses are arranged on the inner peripheral surface of the cylindrical hole. It can be formed. And if it is formed by such a plucking generation method, it will be 1 by milling.
As compared with the case where one groove is sequentially formed, a force such as bending or crushing is less likely to act on the pipe material during processing, so that deterioration of cylindricity can be prevented. Also,
With this manufacturing method, the processing time and the number of processing steps are markedly reduced as compared with milling, so that the manufacturing unit price can be significantly reduced.

Whether the convex portions are formed on both sides of the concave portion in the rotational direction of the developing sleeve or only on one side, the groove depth is improved. So it doesn't matter.

In the second invention of the present application, a tubular material (13) formed in a cylindrical shape is provided on a plurality of projections (12b) on the inner peripheral surface of the cylindrical hole (12a) and the projections (12b). By press-fitting into a molding hole having a shape in which a concave portion (12c) is formed in an adjacent portion, the length of this pipe material is increased on the outer peripheral surface of the pipe material.
A plurality of recesses (1a) for forming a plurality of grooves extending in the direction and a portion adjacent to each recess from the outer peripheral surface.
Is a method for manufacturing a developer carrying body, which manufactures a developing sleeve having a plurality of convex portions (1b) protruding outward .

In the second invention, a cylindrical hole is formed in a molding hole having a plurality of protrusions on the inner peripheral surface of the cylindrical hole and a recess formed in a portion adjacent to the protrusions. Since the plurality of concave portions and the plurality of convex portions are formed on the outer peripheral surface of the cylinder of the developing sleeve by press-fitting the pipe material, it is possible to form the plurality of grooves by arranging them in the rotational direction of the developing sleeve. Moreover, in this manufacturing method, since a plurality of concave portions are simultaneously processed while a plurality of molding projections are in contact with the pipe material at the same time, a substantially uniform force is applied to the pipe material from all directions during processing. Will act simultaneously.
Therefore, as compared with the case where the recesses are sequentially formed by milling, a force such as bending or crushing is less likely to act on the pipe material. In addition, since the processing time and the number of processing steps are remarkably reduced as compared with the milling, the manufacturing unit price is greatly reduced.

In the developing sleeve formed by such a manufacturing method, since the convex portion protruding outward from the outer peripheral surface of the pipe member is formed in the portion adjacent to each recess, the pipe member is formed by milling. As compared with the case where the concave portion is formed by shaving, the depth of the groove can be increased by the amount of the convex portion provided around the concave portion, and the amount of developer conveyed can be improved. On the contrary, when compared with the developer carrying body of the same carry amount, the developing sleeve can be formed to have a smaller diameter than the developer carrying body by milling.

Further, in the developing sleeve formed by such a manufacturing method, the depth of the groove is increased by the amount that the convex portion is arranged around the concave portion, so that the thickness of the pipe material is increased as compared with the case of milling. It becomes possible to form a groove having the same depth by using a thin one. When the wall thickness of the pipe material is reduced in this way, the distance from the magnetic force generating means to the surface of the developing sleeve becomes shorter, so that the magnetic force on the surface of the developing sleeve can be improved, thereby preventing the developer from spilling. be able to.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1A is a perspective view of a developer carrying member of the present invention, FIG.
2B is a cross-sectional view of the developer carrier, FIG. 2 is a schematic configuration diagram of a main part of an image forming apparatus to which the developer carrier is applied, FIG. 3 is an explanatory view of a developing sleeve manufacturing process, and FIG. 4 is a developing sleeve. 5 is an explanatory view of a method of measuring the cylindricity of the toner, FIG. 5 is an explanatory view of setting a developing gap between the developer carrying member and the photosensitive drum, and FIG. 6 is a modification of the concave portion and the convex portion formed on the developing sleeve. It is a figure.

The image forming apparatus according to the present embodiment has a photosensitive drum 4 formed in a cylindrical shape and rotatably arranged.
An image is formed by forming an electrostatic latent image on the cylindrical peripheral surface of the photosensitive drum 4, developing the electrostatic latent image with toner, and transferring and fixing the developed image with the toner onto the paper P. Is formed, and such an image forming method is called an electrophotographic method.

In order to realize such an image forming method, in the image forming apparatus, as shown in FIG.
A uniform charging corotron 5, an exposure operation device (not shown), a developing device 17, and a transfer corotron 6 are arranged around the peripheral part of the photoconductor drum 4 in the rotation direction from the upstream side to the downstream side. In the image forming apparatus configured as described above, first, the outer peripheral surface of the photosensitive drum 4 is charged to a uniform potential by the uniform charging corotron 5, and the exposure operation device exposes the image according to the image information. An electrostatic latent image having a potential distribution according to the density information of is formed on the surface of the photosensitive drum 4. Next, the developing device 17 supplies a charged toner to the electrostatic latent image, so that a toner amount corresponding to the potential distribution is attached to the surface of the photoconductor drum 4 to form a toner image. . Further, the transfer corotron 6 transfers the toner adhering to the photosensitive drum 4 onto the paper P to thereby transfer the toner image onto the paper P, and the fixing device (not shown) heats the paper P onto which the toner image has been transferred. By applying pressure, an image with a predetermined density distribution can be formed on the paper P.

In such an image forming apparatus, the developing device 17 of the present embodiment supplies a two-component developer consisting of toner and magnetic carrier to the photoconductor drum 4 to charge the electrostatic latent image. Is supplying toner. Therefore, the developing device 17 of the present embodiment has a substantially cylindrical outer shape, and the developer carrier 3 arranged so that the cylindrical axes thereof are parallel to the photosensitive drum 4, and the developing device 17. For the developer carrier 3, a paddle 11 for supplying the developer to the developer carrier 3, two augers 9, 10 for mixing and stirring the toner supplied from a toner replenishing device (not shown) with the magnetic carrier, and A trimmer blade 7 which is arranged to face each other with a predetermined minute gap, and which regulates the layer thickness of the developer held on the surface of the developer carrier 3 to a constant value by the width of the gap, and these members 3, 7, And a housing 8 holding 9, 10, and 11. In the following description of the developing device 17, the position close to the photosensitive drum 4 is called the front side, and the position away from the photosensitive drum 4 is called the rear side.

In such a developing device 17, the two augers 9 and 10 are arranged in the housing 8 so as to rotate in parallel with the developer carrying member 3, respectively.
a and 10a, and a stirring member 9 spirally wound around them
b and 10b. These two augers 9 and 10
The auger 10 is arranged on the rear side of the housing 8 and is partitioned by a partition plate 8a standing upright between them, excluding both ends of the rotary shafts 9a and 10a. The developer is conveyed from the back side to the front side, and the auger 9 on the other side conveys the developer from the front side to the back side of the paper surface so that the developer is circulated between the two augers 9 and 10. ing. Then, the toner supplied from the toner replenishing device and the magnetic carrier are mixed and stirred by the circulation of the developer, and the toner can be charged.
The two augers 9 and 10 are rotated counterclockwise in the plane of FIG. 2 so that the charged toner and magnetic carrier can be efficiently supplied to the developer carrying member 3.

The paddle 11 for supplying the developer to the developer carrying member 3 is provided with a paddle rotating shaft 11b arranged in the housing 8 so as to rotate in parallel with the developer carrying member 3, and is erected around the paddle rotating shaft 11b. The plurality of fins 11a are formed, and are arranged between the developer carrying member 3 and the front auger 10. The paddle 11 is also rotated counterclockwise in the plane of FIG. 2, whereby the auger 9,
The developer mixed and stirred by 10 is supplied to the developer carrier 3 from the upper side of the paddle 11, while the developer supplied to the photoconductor drum 4 is supplied from the lower side of the paddle 11 to the augers 9, 10. Is being transported to.

A developer carrying member 3 having a substantially cylindrical outer shape.
Is formed with a plurality of recesses 1a on the outer peripheral surface of the cylindrical pipe material 13 by a drawing method, and the housing 8
Developing sleeve 1 rotatably arranged on the front side of the
And a magnet roll 2 fixedly arranged inside the cylinder of the developing sleeve 1 and having a plurality of magnetic poles magnetized. The developer carrier 3 holds the magnetic carrier and the charged toner electrostatically attached to the magnetic carrier by the magnetic force of the magnet roll 2 on the surface of the developing sleeve 1, and the developing sleeve 1 is reversed on the paper surface of FIG. By rotating clockwise, the held two-component developer is conveyed to a position facing the photoconductor drum 4.

The developing device 1 formed in this way
7, the two augers 9 and 10 mix and stir the two-component developer to charge the toner, and the charged toner and the magnetic carrier are supplied to the developer carrier 3 by the paddle 11.
The trimmer blade 7 adjusts the amount of the developer held on the developer carrying member 3 to a constant amount, and further supplies the developer composed of the charged toner and the magnetic carrier to the photosensitive drum 4 by the rotation of the developer carrying member 3. By doing so, the electrostatic latent image having a predetermined potential distribution formed on the photosensitive drum 4 can be developed with a magnetic brush made of a developer. The developer which has not been used for the development is returned to the inside of the developing device 17 by the rotation of the developer carrying member 3 and then mixed and stirred with new toner again by the augers 9 and 10 through the paddle 11. It is reused for the next development.

Next, a method of molding the developing sleeve 1 of this embodiment will be described with reference to FIG. The developing sleeve 1 of this embodiment is formed by press-fitting a cylindrical tube material 13 into a die 12 as shown in FIG. The die 12 has a cylindrical hole 12a having substantially the same diameter as the outer circumference of the pipe material 13, and a plurality of protrusions 12b having a substantially isosceles triangular cross section are arranged at equal intervals on the inner peripheral surface of the cylindrical hole 12a. ,
In addition, each of the protrusions has a molding hole in which a recess 12c is provided at a portion adjacent to both sides of the protrusion. Then, the die 12 is arranged in the container of the drawing machine in which the cylindrical pipe material 13 is set, and when a large force in the direction toward the die 11 is applied to the pipe material 13, the pipe material 13 becomes a molding hole of the die. As a result, it is inserted (c)
As shown in FIG. 3, the outer peripheral surface of the pipe member 13 is formed with the same number of substantially V-shaped recesses 1a as the protrusions 12b along the cylindrical axis, and the protrusions are formed at the portions adjacent to both sides of each recess 1a. The part 1b is formed. In this pultrusion molding method, a substantially uniform force acts on the pipe material 13 from all directions at the same time, and therefore a force that bends or crushes the pipe material 13 hardly acts.

In this embodiment, as shown in FIG. 3B, the length is 322 mm, the diameter is 18 mm, and the wall thickness is 0.75 m.
Using aluminum pipe material 13 of m, 40 to 70 concave portions 1a of a substantially isosceles triangle having a width of 0.3 mm, a depth of 0.15 mm and an apex angle of 90 degrees were formed on this surface. Further, the convex portion 1b had a cross-sectional area that was approximately half or less of the cross-sectional area of the concave portion 1a, and the height of the convex portion was approximately half or less of the depth of the concave portion 1a. By the way, when 70 or more recesses 1a are formed, the force applied to the pipe material 13 when cutting the recesses 1a becomes extremely large, and therefore, this pultrusion method is difficult to form.

The developing sleeve 1 formed by such a method
Was measured by the inspection method shown in FIG. In this inspection method, first, the probe 14 is brought into contact with the surface of the developing sleeve 1, and when the probe 14 is moved in the rotation direction of the developing sleeve 1 in this state, the deflection in a direction perpendicular to the contact surface of the probe 14 is caused. The width (ΔX) is measured, and the cylindricity of the developing sleeve 1 is measured by the deflection width (ΔX) of the probe. In the developing sleeve 1 according to this embodiment, the swing width (ΔX) of the probe 14 in the peripheral surface portion other than the concave portion 1a and the convex portion 1b is set to 30 μm or less.

Further, when the magnet roll 2 is disposed in the developing sleeve 1 formed by such a method, on the main pole of the magnet roll 2, a portion other than the concave portion 1a or the convex portion 1b on the surface of the developing sleeve 1 is formed. 10 when measured
A magnetic force of 0 mT or more was measured.

When an image is formed on the sheet P using the image forming apparatus having the developing sleeve 1 arranged as described above, the image is surrounded not only by the concave portion 1a but also by the convex portions 1b formed on both sides thereof. The developer is accommodated up to the open region, and since the developing sleeve 1 is formed by using the thin tube material 13, the density of the developer adhering to the surface of the developing sleeve 1 is also improved. As a result, despite the diameter of the developing sleeve 1 being reduced to 18 mm,
Sufficient developer could be stably supplied to the photosensitive drum 4, and an image could be formed with an appropriate image density.

Moreover, in the image forming apparatus of this embodiment,
As shown in FIG. 5, the development gap, which is the distance between the photoconductor drum 4 and the developer carrying member 3, can be suppressed within a range of 500 μm ± 50 μm on the line segment connecting the rotation axes of the two. In addition, the density unevenness due to the deterioration of the cylindricity of the developing sleeve 1 was not generated.

FIG. 6 shows a modification of the concave portion 1a and the convex portion 1b. The figure (a) is a shape formed when a die 12 having a hole shape similar to that of the present embodiment is used. By changing the hole shape of this die, the shape shown in (b) and (d) of FIG. It is also possible to form the convex portion 1b only on one side of the concave portion 1a as shown, or to form the substantially U-shaped concave portion 1a as shown in FIGS.

[0032]

As described in detail above, in the first invention of the present application, the developing sleeve is arranged on the outer peripheral surface of the cylindrical pipe material in the rotational direction of the developing sleeve .
Since a plurality of concave portions for forming a plurality of grooves extending along the longitudinal direction and a plurality of convex portions projecting outward from the outer peripheral surface are formed in a portion adjacent to each concave portion, the developing sleeve While reducing the distance between the magnetic force generating means and the surface of the developing sleeve by using a thin wall as
Deep grooves can be formed. Therefore, the transport amount of the developer can be increased as compared with the case where the recess is simply formed.

Further, in the developing sleeve in which the plurality of concave portions and the plurality of convex portions are formed on the outer peripheral surface as described above, the plurality of protruding portions and the plurality of concave portions are arranged on the inner peripheral surface of the cylindrical hole. It can be formed by press-fitting a cylindrical pipe material into the formed molding hole. When the extrusion molding method is used as described above, deterioration of cylindricity can be suppressed as compared with the case where the recess is formed by milling, and the diameter of the pipe material is 20 mmφ or less and the wall thickness is 1m
It is possible to suppress the occurrence of density unevenness even if a material of about m is used.

In the second invention of the present application, a cylindrical hole is formed in a molding hole having a plurality of protrusions on the inner peripheral surface of the cylindrical hole and a recess formed in a portion adjacent to the protrusions. by press-fitting the tubing, the length of the tube material to the outer peripheral surface of the pipe material
Outer than the outer peripheral surface at a plurality of recesses for forming a plurality of grooves extending in the hand direction and a portion adjacent to each recess
Since the plurality of convex portions protruding in the direction are formed, the developing sleeve can be molded without applying a force such as bending or crushing to the pipe material. Therefore, it becomes possible to suppress the deterioration of the cylindricity as compared with the case where the recess is formed by milling, and the diameter of the pipe material is 20 mm.
It is possible to suppress the occurrence of density unevenness even if the thickness is less than or equal to mmφ and the thickness is about 1 mm.

Further, in the developing sleeve formed by such a manufacturing method, since the convex portions protruding outward from the outer peripheral surface of the pipe material are formed in the portions adjacent to the respective concave portions, the pipe material can be processed like milling. As compared with the case where the concave portion is formed by shaving, the depth of the groove can be increased by the amount of the convex portion provided around the concave portion, and the amount of developer conveyed can be improved. In addition, since the depth of the groove is improved by the amount that the convex portion is arranged around the concave portion, the groove of the same depth can be used by using a pipe material with a thinner wall thickness than in the case of milling. It is possible to form it. By reducing the wall thickness of the pipe material in this way, it is possible to improve the magnetic force on the surface of the developing sleeve and prevent the developer from spilling.

[Brief description of drawings]

FIG. 1 is a developer carrier according to Embodiment 1 of the present invention ((a) is a perspective view, (b) is a cross-sectional view).

2 is a schematic configuration diagram of a main part of an image forming apparatus to which the developer carrier of FIG. 1 is applied.

FIG. 3 is an explanatory view of a manufacturing process of a developing sleeve.

FIG. 4 is an explanatory diagram of a method for measuring the cylindricity of the developing sleeve.

FIG. 5 is an explanatory diagram of setting a developing gap between a developer bearing member and a photosensitive drum.

FIG. 6 is a modified example of a concave portion and a convex portion formed on a developing sleeve.

[Explanation of symbols]

1: developing sleeve, 2: magnet roll, 13: pipe material, 12: die, 12a: cylindrical hole, 12b: protrusion,
12c: concave portion, 1a: concave portion, 1b: convex portion.

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Claims (2)

(57) [Claims] 1. A developing sleeve, which comprises a cylindrical developing sleeve and magnetic force generating means disposed inside the cylinder of the developing sleeve, and holds the developer on the surface of the developing sleeve by the magnetic force of the magnetic force generating means. A developer carrier that conveys the retained developer by the rotation of the sleeve, the developing sleeve being arranged on the outer peripheral surface of a cylindrical pipe material in the rotation direction of the developing sleeve, and extending in the longitudinal direction of the pipe material.
A plurality of recesses for forming a plurality of grooves extending therethrough, and a plurality of protrusions protruding outward from the outer peripheral surface at a portion adjacent to each recess. Carrier. 2. A tubular material formed into a cylindrical shape is press-fitted into a molding hole having a plurality of protrusions on the inner peripheral surface of the cylindrical hole and a recess formed in a portion adjacent to the protrusion. On the outer peripheral surface of the pipe along the longitudinal direction of the pipe.
A plurality of recesses and each recess for forming a building a plurality of grooves
A plurality of adjacent parts protruding outward from the outer peripheral surface
A method of manufacturing a developer carrier, comprising manufacturing a developing sleeve having a convex portion .