JP2002066296A - Insert molding rotary member, developer stirring member of image forming apparatus, image forming apparatus and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a stirring member high in rigidity and accuracy used in a process cartridge. SOLUTION: In an insert molding rotary member used in an image forming apparatus, the longitudinal dimension of an insert member is shorter than that of a mold member and the outer diameter of the insert member is made smaller than that of the mold member and the insert member is almost covered with the mold member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insert molding rotary member, a developer stirring member of an image forming apparatus using the insert molding rotary member, an image forming apparatus, and a process cartridge detachable from a main body thereof.

Here, the image forming apparatus is an electrophotographic image forming apparatus that forms an image on a photosensitive drum using an electrophotographic method. Examples of the electrophotographic image forming apparatus include, for example, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, and the like), a facsimile machine, a word processor, and the like.

Further, the process cartridge includes a charging unit, a developing unit or a cleaning unit, and a photosensitive drum which are integrally formed into a cartridge, and the cartridge is detachable from an image forming apparatus main body. At least one of the developing means and the cleaning means and the electrophotographic photosensitive drum are integrally formed as a cartridge so that the cartridge can be attached to and detached from the image forming apparatus main body. Further, at least the developing means and the photosensitive drum are integrally formed into a cartridge so as to be detachable from the apparatus main body.

[0004]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image process, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is mounted on the main body of the image forming apparatus. A process cartridge system which can be attached to and detached from is used.

According to this process cartridge system,
Since the maintenance of the apparatus can be performed by the user himself without relying on a service person, the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

In recent years, the speed of an image forming apparatus using an electrophotographic image process has been increased, and a developing container which continuously supplies a larger amount of toner from the developing container to a photosensitive drum has been required. Therefore, to supply the developer, it is necessary to rotate a developer stirring member such as a screw at high speed.

Further, the process cartridge around the photoreceptor drum is treated as a replacement part, so that the user can use the photoconductor drum efficiently and more closely. Therefore, the cost of the process cartridge and the price of the developer stirring member are reduced. There is a need.

[0008]

However, when the screw-shaped developer stirring member is rotated at a high speed, the eccentric rotation may occur due to the toner conveyance resistance.

Therefore, in order to maintain the rigidity of the developer stirring member, an insert molded body obtained by insert molding a core metal as an insert member may be used. That is, FIG.
As shown in FIG. 1, in the conventional developer stirring member 100 of insert molding, a penetrating type in which an insert shaft 101 protrudes from both ends of a mold portion 102 has been used.

However, in order to transmit the drive to the insert shaft 101, the D-cut 10
Secondary processing is required for rotary joints such as 3. Further, since the sliding is performed on the metal surface, secondary processing in the grinding process is required for the rotation supporting portion 104 at the end, and there is a problem that the cost is significantly increased.

The present invention eliminates the above-mentioned high cost factors of the conventional insert-molded rotary member, and provides a high-rigidity, high-precision insert-molded rotary member that satisfies stable performance at a low cost. An object is to provide a member, an image forming apparatus, and a process cartridge.

[0012]

The main aspects of the present invention are as described below with reference to the claims.

According to a first aspect of the present invention, in an insert-molded rotary member in which an insert member is integrally formed with a mold portion, a longitudinal dimension of the insert member is shorter than a length of the mold portion, and an outer diameter of the insert member. Is smaller than the outer diameter of the mold portion so that the insert member is almost covered with the mold, and a rotating joint portion and a rotation support portion for transmitting a driving force are provided in the mold portion.

The developer stirring member of the image forming apparatus according to a second aspect of the present invention is characterized in that the mold portion of the insert molding rotary member is formed into a screw spiral shape for conveying the developer.

A third invention according to the present application is characterized in that an inverse spiral-shaped portion is provided in a downstream portion of the mold portion where the developer is conveyed.

An image forming apparatus according to a fourth aspect of the present invention includes a photosensitive drum on which an image is formed, and developing means for developing an electrostatic latent image formed on the photosensitive drum, The developing means has a developer stirring member according to claim 2 or 3 for supplying a developer to a photosensitive drum.

According to a fifth aspect of the present invention, there is provided a process cartridge comprising: a photosensitive drum on which an image is formed; developing means for developing an electrostatic latent image formed on the photosensitive drum;
Wherein the developing means has the developer stirring member for supplying a developer to the photosensitive drum.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

In the following description, the longitudinal direction refers to a direction crossing the transport direction of the recording medium and parallel to the recording medium. The left and right are the left and right as viewed in the transport direction of the recording medium. Further, "above the process cartridge" means above the process cartridge in the mounted state.

FIG. 1 is a diagram showing an image forming apparatus to which the present invention is applied.

This image forming apparatus comprises image forming units 31Y, 31M, 31C, 31BK for forming toner images on photosensitive drums 7Y, 7M, 7C, 7BK as image carriers.
An intermediate transfer belt 4a for temporarily transferring the toner image, a secondary transfer roller 40 serving as a transfer unit for transferring the toner image on the belt 4a to the recording medium 2, and an intermediate transfer belt 4a and a secondary transfer roller 40 for transferring the recording medium 2 to the intermediate transfer belt 4a. The sheet feeder 3 feeds the image to the space, a fixing device 5 as a fixing unit for fixing the image of the recording medium 2 after the transfer, and a discharge roller pair 3h as a sheet discharge unit.
3i.

Hereinafter, image formation will be described.

As shown in the figure, a plurality of recording media (for example, recording paper, OHP sheet, cloth, etc.)
Is removably mounted, and the paper is conveyed to the transfer unit through the paper conveyance unit 3. That is, in the sheet feeding / conveying section 3, the recording medium 2 fed from the sheet feeding cassette 3a by the pickup roller 3b.
Are separated one by one by the retard roller pair 3c,
The sheet is conveyed to the pair of registration rollers 3g by the conveying rollers 3d and 3f.

When the recording medium 2 is conveyed, the registration roller pair 3g stops rotating, and the skew of the recording medium 2 is corrected by hitting the nip.

In the case of the four-drum full-color system, four process cartridges of yellow, magenta, cyan, and black are arranged in parallel in the process cartridges BY, BM, BC, and BB including the photosensitive drums 7Y, 7M, 7C, and 7BK. ing.

Each of the process cartridges BY, BM,
The optical scanning systems 1Y, 1M, and 1 correspond to BC and BB, respectively.
C, 1BK are provided, and after a toner image is formed on the photosensitive drum for each color by an image signal, the transfer roller 4
By Y, 4M, 4C, and 4BK, the respective color toners are superimposedly transferred onto the intermediate transfer belt 4a running in the direction of the arrow shown in the figure.

Thereafter, the recording medium 2 is sent to the secondary transfer roller 40 at a predetermined timing, and the toner image on the intermediate transfer belt 4a is transferred onto the recording medium 2, and the fixing device 5
Is discharged by the discharge roller pairs 3h and 3i, and is stacked on the tray 6 on the apparatus main body 14.

The image forming units 31Y, 31M, 31C,
31BK are process cartridges BY, BM, and B, respectively, except for the optical scanning systems 1Y, 1M, 1C, and 1BK.
C, BB and toner containers TY, TM, TC, TB. Process cartridges BY, BM, BC, BB
Are the same, the process cartridge BY will be described as an example.

As shown in FIG. 2, the process cartridge BY has a charging means, an exposure unit, a developing means, and a transfer opening provided around a photosensitive drum 7. In this embodiment, a two-component developer having a magnetic carrier powder is used.

The charging means is a magnetic brush charger 8 using a magnetic carrier. The charger 8 has a fixed magnet 8b disposed inside a hollow cylindrical charging roller 8a rotatably supported. After the transfer, the toner remaining on the photosensitive drum 7 is taken into the charger 8 which rotates in the direction of the arrow shown in the figure.

In the present embodiment, a developing method in which a two-component developer is brought into contact with the developing means (two-component non-contact development) is employed.

FIG. 2 shows the structure of the second embodiment used in this embodiment.
Developing means 10 for component magnetic brush development is shown.

The developing sleeve 10d has a hollow cylindrical shape and is rotatably supported. A fixed magnet 10c is provided in the developing sleeve 10d. The developing sleeve 10d rotates in the same direction as the photosensitive drum 7, and the peripheral surface moves in a direction opposite to the moving direction of the peripheral surface of the photosensitive drum 7.

The photosensitive drum 7 and the developing sleeve 10d are not in contact with each other and have a gap of about 0.2 to 1.0 mm so that development can be performed in a state where the developer contacts the photosensitive drum 7. Is set. Since the image forming apparatus of this embodiment has a printing capacity of 20 to 30 sheets / min, the rotation speed of the photosensitive drum 7 is about 75 rpm, and the developing sleeve 10
Is set to about 230 rpm.

The toner mixed with the carrier is supplied by a stirring screw 10g, 10h as a developer stirring member in a casing partitioned by a longitudinal partition wall 10f excluding both ends.

The toner supplied from the toner container TY is
The mixture is dropped on one end of the stirring screw 10g, stirred while being sent in one longitudinal direction, passes through a portion without the partition 10f on the other end, and moves to one end with the stirring screw 10h. Next, the mixture is stirred and circulated while being sent by the stirring screw 10h through a portion without the partition wall 10f on one end side.

Both the stirring screw 10g and the stirring screw 10h rotate at a high speed of about 330 rpm to stir and transport the two-component developer in order to supply the developer to the developing sleeve 10d rotating at a high speed.

Here, the developing step of visualizing the electrostatic latent image formed on the photosensitive drum 7 by the two-component magnetic brush method using the developing device 4 and the circulation system of the developer will be described.

First, the developer pumped up by the poles of the magnet 10c with the rotation of the developing sleeve 10d is regulated by the regulating blade 10e, that is, the developing blade arranged perpendicular to the developing sleeve 10d in the process of being transported. Then, a thin layer is formed on the developing sleeve 10d. When the developer having a thin layer formed thereon is conveyed to the developing main pole, ears are formed by magnetic force. The electrostatic latent image on the photosensitive drum 7 is developed with the spike-shaped developer, and the developer on the developing sleeve 10d is returned to the developing container 10a by the repulsive magnetic field.

A DC voltage and an AC voltage are applied to the developing sleeve 10d from a power source (not shown). In general, in the two-component developing method, when an AC voltage is applied, the developing efficiency is increased and the quality of an image is high, but on the contrary, fogging is likely to occur. Therefore, usually, by providing a potential difference between the DC voltage applied to the developing sleeve 10d and the surface potential of the photosensitive drum 7, it is possible to prevent toner from adhering to the non-image area during development.

Next, a stirring screw as a rotary member for insert molding will be described.

FIG. 3 shows a top projection view of the stirring screw 10h and a sectional view of both ends. The stirring screw 10g has the same configuration, and the description is omitted.

The stirring screw 10h stirs and transports the two-component developer at a high speed as described above. Since the two-component developer contains a magnetic carrier, the load during the transport rotation is large, and when the rotation speed exceeds a certain range, the eccentric rotation starts due to the screw rigidity and the runout accuracy of the screw outer diameter.

In this embodiment, the stirring screw 10h
In order to increase the rigidity of the screw so as not to cause eccentric rotation, the insert member 13 of the round shaft is
Insert molding is carried out so as to be covered in 5. When used in a process cartridge like the stirring screw 10h of the present embodiment, it is necessary to reduce costs as much as possible in order to reduce printing costs.

Therefore, the longitudinal dimension of the insert member 13 is shorter than the length of the mold section 15 and the outer diameter of the insert member 13 is smaller than the outer diameter of the mold section 15.
Shaft coupling 15 as a rotary coupling for transmitting driving force
a and the rotation support portion 15 b are provided in the mold portion 15. The mold part 15 is formed in a screw spiral shape for transporting the developer.

In the present embodiment, in order to cover the insert member 13 with the mold member 15, the depth of the hole formed at the end of the mold member 15 is changed to a D-cut shaft coupling 15 b.
And the opening side of the hole is a circular rotation support portion 15a.

By using the insert member 13 only as a reinforcing member that covers the inside of the mold member 15 as described above, the secondary processing of shaft grinding and shaft splicing, which has become a high cost factor of the insert molding stirring screw, is performed. This makes it unnecessary to provide an insert molding stirring screw at low cost.

In the present embodiment, a stirring screw 10 g,
10 h are used, and the developer is transported and circulated in the longitudinal direction by a screw spiral shape. for that reason,
On the downstream side in the transport direction of each of the stirring screws 10g and 10h, a reverse spiral-shaped portion 16 for promoting developer circulation is arranged for two rotations.

Thus, it is possible to prevent the developer from accumulating in the bearing portion on the downstream side in the conveying direction of the stirring screw.
High-speed rotation of the developer circulation can be maintained for a long lifetime.

In the above embodiment, an example using a process cartridge has been described. However, it is needless to say that the present invention can be applied to a developing agitating member of a developing device when no process cartridge is used.

In the above embodiment, the insert rotating member is applied as the developing agitating member in the process cartridge, but the present invention is not limited to this.

[0052]

As described above, according to the present invention,
By embedding the insert member of the insert molding rotary member such as the developer stirring member of the image forming apparatus in the mold, the grinding of the shaft and the secondary processing of the shaft joint, which have been high cost factors, become unnecessary, and the insert member is eliminated. Can be simplified and inexpensive.

In particular, by forming the shaft joint portion by molding, the precision of parts such as screw runout based on the joint can be increased.

Further, by disposing the reverse spiral shape downstream of the developer stirring member in the transport direction, high-speed rotation and circulation can be maintained throughout the life of the process cartridge.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electrophotographic image forming apparatus to which a stirring screw according to an embodiment of the present invention is applied.

FIG. 2 is a longitudinal sectional view of a process cartridge of the image forming apparatus of FIG.

FIG. 3 is a top projection view of the stirring screw of FIG. 1 and an enlarged view of both ends.

FIG. 4 is a cross-sectional view of both ends of a conventional stirring screw.

[Explanation of symbols]

BY, BM, BC, BB: Process cartridge TY, TM, TC, TB: Toner container 1Y, 1M, 1C, 1BK: Scanning optical system 2: Recording medium 3: Paper feeder 3a: Paper feed cassette, 3b: Pickup Roller, 3
d, 3f: conveyance roller, 3g: registration roller pair, 3
c: retard roller pair, 3b, 3i: discharge roller pair, 4
a: intermediate transfer belt, 5: fixing device, 6: tray 4Y, 4M, 4C, 4BK: transfer roller 7Y, 7M, 7C, 7BK: photosensitive drum 8: magnetic brush charger, 8a: charging roller, 8b: Magnet, 8c: regulating blade 10: developing means, 10c: magnet, 10d: developing sleeve, 10e: regulating blade, 10f: partition 10g, 10h: stirring screw 13: insert member, 15: molded part, 15a: shaft coupling part, 15b: Rotation support unit 31Y, 31M, 31C, 31BK: Image forming unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naofumi Horikawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takato Ueno 3-30-2 Shimomaruko, Ota-ku, Tokyo 2H077 AB02 AC02 AC11 AD02 AD06 EA03 EA15 FA00 GA13 4G037 DA23 EA03 4G078 AA16 AB11 BA01 BA07 DA09

Claims (5)

[Claims] 1. An insert-molded rotary member in which an insert member is integrally formed with a mold portion, wherein a longitudinal dimension of the insert member is shorter than a length of the mold portion, and an outer diameter of the insert member is smaller than an outer diameter of the mold portion. An insert-molded rotary member, wherein a rotary joint for transmitting a driving force and a rotary support are provided in the mold. 2. A developer stirring member for an image forming apparatus, wherein a mold portion of the rotary member for insert molding according to claim 1 is formed into a screw spiral shape for conveying a developer. 3. The developer stirring member of the image forming apparatus according to claim 2, wherein a reverse spiral-shaped portion is provided at a downstream side of the developer conveyance of the mold portion. 4. A photosensitive drum on which an image is formed, and developing means for developing an electrostatic latent image formed on the photosensitive drum, wherein the developing means supplies a developer to the photosensitive drum. An image forming apparatus comprising the developer stirring member according to claim 2. 5. A photosensitive drum on which an image is formed, and developing means for developing an electrostatic latent image formed on the photosensitive drum, wherein the developing means supplies a developer to the photosensitive drum. A process cartridge comprising the developer stirring member according to claim 2.