JP3332582B2 - Electrophotographic photosensitive drum, process cartridge, and image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive drum used for image formation, a process cartridge having the electrophotographic photosensitive drum, and an image forming apparatus for forming an image by mounting the process cartridge. Related to the device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a printer, a latent image is formed by selectively exposing an image carrier uniformly charged by a charger to a latent image, and the latent image is developed with a developer by a developing device. At the same time, the image is formed by transferring the image formed by the developer onto a recording medium. In such an apparatus, maintenance of each member is performed by a specialized service person.

Therefore, the image carrier, the charger, the developing device,
The cleaning unit and the like are integrated into a cartridge to form a cartridge, so that the user can load the cartridge into the apparatus main body, thereby replenishing the developer and exchanging parts of the image carrier having reached the end of its life, thereby facilitating maintenance. Has been put to practical use.

[0004] In such a process cartridge, as shown in FIG.
The image bearing member 50 is rotatably supported by a helical drum gear 52 attached to one end of the image carrier 50 to receive rotational force from the apparatus main body, and a flange gear 53 attached to the other end applies rotational force to the developing roller. It is configured to communicate.

The drum gear 52 and the flange gear 53 must be easily moldable and have good meshing accuracy. Therefore, conventionally, these gears are formed by injection-molding a synthetic resin, and at this time, a lightening portion 54 is provided inside the tooth bottom of the gear. This is to make the shrinkage of the molded part uniform over the entire tooth surface, to reduce the influence of shrinkage, and to increase the meshing accuracy.

[0006]

However, when the lightening portion 54 is provided in the gear 52 as described above, the strength of the gear in the radial direction of rotation decreases as the tooth width increases (particularly, the gear tooth tip portion). Therefore, when the load at the time of drive transmission becomes heavy,
The gear tooth surface is easily deformed, so that the drive transmission efficiency is not constant, and pitch unevenness occurs at one gear tooth pitch. As a result, image quality may be reduced.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an electrophotographic photosensitive drum in which a drum gear does not deform even when a load becomes heavy.
Another object of the present invention is to provide a process cartridge having the electrophotographic photosensitive drum and an image forming apparatus to which the process cartridge can be attached and detached.

[0008]

In order to achieve the above object, a typical configuration according to the present invention is an electrophotographic photosensitive drum used in a process cartridge detachable from an image forming apparatus main body. A cylinder made of a synthetic resin material, a drum gear provided at one end in the axial direction of the cylinder, and a shaft hole provided in the drum gear fitted with a shaft provided in a cartridge frame of the process cartridge. A shaft hole for rotatably supporting the electrophotographic photosensitive drum with respect to the process cartridge; a lightening portion provided between the shaft hole and a tooth bottom of the drum gear; A reinforcing member made of the same material as the drum gear and pressed into the lightening portion, the reinforcing member being configured to suppress deformation of a tooth surface of the drum gear. It is characterized in.

[0009]

In the above construction, the deformation of the tooth surface of the drum gear can be suppressed by providing the reinforcing member at the lightening portion. Furthermore, since the drum gear and the reinforcing member are made of the same synthetic resin material, the thermal expansion and the thermal contraction of the drum gear and the reinforcing member are equal in size. The surface is not deformed by the reinforcing member, and conversely, an unnecessary gap is generated between the drum gear and the reinforcing member, and the effect of suppressing the deformation of the gear tooth surface is not impaired. In addition, the press-fitting between the drum gear and the reinforcing member is loosened, and the reinforcing member does not come off.

[0010]

Next, as an embodiment according to the present invention, an image forming apparatus to which a process cartridge can be mounted will be specifically described with reference to the drawings.

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram of a configuration of an image carrier in a process cartridge, FIG. 2 is an explanatory diagram of an image forming apparatus in which the process cartridge is mounted, FIG. 3 is an explanatory diagram of a configuration of the process cartridge, and FIG. 5A and 5B are explanatory views of the mounting configuration of the process cartridge.

Here, as a sequence of the description, first, an overall configuration of a process cartridge and an image forming apparatus equipped with the process cartridge will be described with reference to FIGS. 2 to 5, and then a photoconductor having a gear will be described with reference to FIG. The configuration of the drum will be described.

<< Overall Configuration >> This image forming apparatus A is shown in FIG.
As shown in (1), a laser light image based on image information is emitted from the optical system 1 to form a toner image on a photosensitive drum as an image carrier. And, in synchronization with the formation of the toner image,
The recording medium 2 is moved from the cassette 3a to the pickup roller 3b.
And a toner image formed on the photosensitive drum as a transfer unit in an image forming unit which is transported by the transport unit 3 including a feed roller 3c, a transport roller 3d, a registration roller 3e, and the like, and is formed into a cartridge as the process cartridge B. The transfer is performed on the recording medium 2 by applying a voltage to the transfer roller 4, and the recording medium 2 is guided by the guide plate 3 f and conveyed to the fixing unit 5. The fixing means 5 includes a driving roller 5a and a fixing roller 5c having a heater 5b therein, and applies heat and pressure to the recording medium 2 passing therethrough to fix the transferred toner image. The recording medium 2 is conveyed by a pair of discharge rollers 3g and 3h, and is discharged to a discharge section 6 through a reverse conveyance path. The image forming apparatus A can also be manually fed by a manual tray 3i and a roller 3j.

On the other hand, as shown in FIGS. 2 and 3, a process cartridge B for forming the image forming section rotates a photosensitive drum 7 having a photosensitive layer and transfers the surface to a charging roller 8 serving as a charging means. , And the latent image is formed by exposing the light image from the optical system 1 to the photoreceptor drum 7 via the exposure unit 9 to form a latent image, and the latent image is developed by the developing unit 10. I have.

The developing means 10 sends out the toner in the toner reservoir by a toner sending member 10a, rotates a developing roller 10c having a fixed magnet 10b therein, and a developing blade.
A toner layer provided with a triboelectric charge by 10d is formed on the surface of the developing roller 10c, and the toner is transferred to the photosensitive drum 7 in accordance with the latent image to form a toner image and visualize the toner image. Then, after applying a voltage having a polarity opposite to that of the toner image to the transfer roller 4 to transfer the toner image to the recording medium 2, the cleaning blade 11a scrapes off the toner remaining on the photosensitive drum 7, and scoops it with the squeeze sheet 11b. The residual toner on the photosensitive drum 7 is removed by the cleaning means 11 for collecting and collecting the waste toner in the waste toner reservoir 11c.

The components such as the photosensitive drum 7 are housed in a cartridge frame in which a first frame 12 and a second frame 13 are combined and formed into a cartridge. It is detachably attached to the attachment means.

When the opening / closing member 15 is opened about the shaft 15a, the cartridge mounting guide member 16 is mounted opposite to the left and right inner side surfaces of the cartridge mounting space, as shown in FIGS. The left and right guide members 16 are provided with opposing guide portions 16a for inserting the process cartridge B. The process cartridge B is inserted along the guide portion 16a, and the opening / closing member 15 is closed.
Is mounted on the image forming apparatus A.

{Photosensitive Drum Having Gears} Next, the structure of the photosensitive drum 7 having gears will be described. The photosensitive drum 7 is formed by applying a photosensitive member (for example, having an organic photosensitive layer) to the surface of a cylindrical member. As shown in FIG. 1, a drum gear 17 (helical gear) is attached to one end in the longitudinal direction. And a flange gear 18 (a spur gear) is attached to the other end. When the process cartridge B is mounted on the image forming apparatus A, the drum gear 17
The drive provided in the gear meshes with the helical gear 19 (see FIG. 5). During image formation, the image forming apparatus rotates by receiving a driving force from a driving gear 19, and the rotating force is transmitted to the transfer roller 4 provided on the apparatus main body via the flange gear 18. That is, the flange gear 18 meshes with a transfer roller gear (not shown) integrally attached to the transfer roller 4 to rotate the transfer roller 4. When the drum gear 17 receives the driving force from the driving helical gear 19 and the driving force is transmitted to the photosensitive drum 7, the photosensitive drum 7 is urged in the thrust direction and the inner wall of the cartridge. (Not shown).

A shaft hole 17a is provided on a side surface of the drum gear 17, and a shaft portion 18a protrudes from a side surface of the flange gear 18. An insertion hole for inserting the metal shaft 20 is provided on one side surface of the second frame 13 on which the photosensitive drum 7 is mounted.
A shaft hole 13b for fitting the shaft portion 18a is provided on the other side surface. The shaft portion 18a of the flange gear 18 is fitted into the shaft hole 13b, and the drum gear
The metal shaft 20 is fitted into the shaft hole 17a of the 17 and the metal shaft 20 is
The photosensitive drum 7 is rotatably attached to the frame 13 by fixing the photosensitive drum 7 to the frame 13 with screws or the like.

Here, the drum gear 17 will be described. It must be easy to manufacture and high in meshing accuracy. For this purpose, it is manufactured by injection molding a synthetic resin such as a polyacetal resin or a polycarbonate resin. At the time of this injection molding, in order to equalize the shrinkage over the entire tooth surface, reduce the influence of shrinkage, and increase the meshing accuracy, a hollow portion 17b is provided inside the tooth bottom, and the portion is formed thin. In order to reinforce the deformation of the tooth surface at the lightening portion 17b, a reinforcing portion is provided at the lightening portion 17b. In this embodiment, the reinforcing portion is formed by attaching the reinforcing member 21 to the lightening portion 17b.

The material of the reinforcing member 21 is not particularly limited, but is preferably made of a polyacetal resin or the like of the same material as the drum gear 17. The reinforcing member 21 can be attached by press-fitting, bonding, screwing,
Alternatively, a method such as so-called snap-fit locking, in which a locking claw is provided on the lightening portion 17b and the reinforcing member 21 fitted with the claw is locked, is appropriately used according to the material and size of the drum gear 17 and the reinforcing member 21. I just need.

The size of the reinforcing member 21 is such that the difference between the inner diameter of the hollow portion 17b into which the reinforcing member 21 is fitted and the outer diameter of the reinforcing member 21 is zero.
It is desirable to set the thickness to about 200 μm, preferably about 0 to 100 μm, and most preferably about 0 to 50 μm. The reason is that if the size of the reinforcing member 21 becomes larger than the above-mentioned size (the lightening portion 17 into which the reinforcing member 21 fits).
b), the tooth tip of the gear 17 is enlarged.
This is because the reinforcing effect cannot be obtained so much because it does not adhere to the inner periphery of 17b.

In this embodiment, the inner diameter (diameter of the hole) D1 =
A reinforcing member 21 made of a polyacetal resin having an outer diameter of D2 = 25.4 mm and a diameter of 11 mm is press-fitted into the lightening portion 17b. When press-fitting the reinforcing member 21, the outer diameter portion may be pressed against the lightening portion 17b, or the inner diameter portion may be pressed against the cylindrical portion 17c of the drum gear 17.

By providing the reinforcing member 21 at the lightening portion 17b of the gear 17 as described above, even if a large load is applied to the gear 17, no deformation occurs at the lightening portion 17b, and the one tooth pitch Can prevent the occurrence of pitch unevenness.
Therefore, the photosensitive drum 7 rotates without rotation unevenness, and a high-quality image is formed without image omission or the like.

In the above-described embodiment, the reinforcing member 21 is formed as a member separate from the drum gear 17, and the reinforcing member 21 is press-fitted into the lightening portion 17b. The same effect can be obtained even if the reinforcing portion is formed by changing the shape of the lightening portion 17b, for example, by providing a reinforcing rib.

[Other Embodiments] Next, other embodiments of the components constituting the process cartridge will be described. First, the image carrier is not limited to the photosensitive drum, but includes, for example, the following. First, a photoconductor is used as a photoconductor, and examples of the photoconductor include amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, and an organic photoconductor (OPC). Further, as the shape on which the photoconductor is mounted, for example, a drum shape,
It includes a rotating body such as a belt and a sheet. In general, a drum-shaped or belt-shaped one is used. For example, in the case of a drum-type photoconductor, a photoconductor is deposited or coated on a cylinder of an aluminum alloy or the like. It is.

Various developing methods such as a known two-component magnetic brush developing method, a cascade developing method, a touch-down developing method, and a cloud developing method can be used as the developing method.

In the first embodiment, a so-called contact charging method is used. However, as another configuration, a metal shield such as aluminum is provided around three sides of a conventionally used tungsten wire. It is a matter of course that a configuration may be used in which positive or negative ions generated by applying a high voltage to the tungsten wire are moved to the surface of the photosensitive drum, and the surface of the drum is uniformly charged.

The charging means may be of a blade type (charging blade), a pad type, a block type, a rod type, a wire type or the like in addition to the roller type.

As a method of cleaning the toner remaining on the photosensitive drum, the cleaning means may be constituted by using a blade, a fur brush, a magnetic brush or the like.

The above-described process cartridge is
It is provided with, for example, an electrophotographic photosensitive member as an image carrier, and at least one of processing means. Therefore, as a mode of the process cartridge, in addition to the above-described embodiment, for example, the image carrier and the charging unit are integrally formed into a cartridge and can be attached to and detached from the apparatus main body. A cartridge in which the image carrier and the developing means are integrated into a cartridge, and which is detachable from the apparatus main body. A device in which the image carrier and the cleaning means are integrally formed into a cartridge and can be attached to and detached from the apparatus main body. Further, there is a type in which an image carrier and two or more of the above-mentioned process means are combined into a cartridge to be detachable from the apparatus main body.

That is, the above-mentioned process cartridge is one in which a charging means, a developing means or a cleaning means and an electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is made detachable from the image forming apparatus main body. . In addition, at least one of the charging unit, the developing unit, and the cleaning unit and the electrophotographic photosensitive member are integrally formed into a cartridge so that the cartridge can be attached to and detached from the image forming apparatus main body. Further, it means that at least the developing means and the electrophotographic photosensitive member are integrally formed into a cartridge so as to be detachable from the apparatus main body.

In the above-described embodiment, the photosensitive drum and the developing sleeve are formed into a cartridge, and an apparatus for forming an image by mounting the process cartridge is illustrated. However, the photosensitive drum and the developing sleeve are not formed into a cartridge. For image forming devices that are directly attached to the main unit,
It can be similarly applied to the present invention.

Further, in the above-described embodiment, a laser beam printer is exemplified as an image forming apparatus. However, the present invention is not limited to this. For example, an electrophotographic copying machine, a facsimile apparatus, or another image forming apparatus such as a word processor. Of course, it is also possible to use.

[0035]

As described above, according to the present invention, the deformation of the tooth surface of the drum gear can be suppressed by providing the reinforcing member at the lightening portion.

Further, since the drum gear and the reinforcing member are made of the same synthetic resin material, the thermal expansion and contraction of the drum gear and the reinforcing member are the same, so that the reinforcing member can be provided in the hollow portion. The tooth surface of the drum gear is not deformed by the reinforcing member, and conversely, an unnecessary gap is generated between the drum gear and the reinforcing member, so that the effect of suppressing the deformation of the tooth surface of the gear is not impaired.

Further, since the drum gear and the reinforcing member are made of the same synthetic resin material, the press-fit between the drum gear and the reinforcing member is loosened, and the reinforcing member does not come off.

[0038]

[0039]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of a photosensitive drum to which a gear is attached.

FIG. 2 is an explanatory diagram illustrating a configuration of an image forming apparatus in which a process cartridge is mounted.

FIG. 3 is an explanatory diagram of a configuration of a process cartridge.

FIG. 4 is an explanatory diagram of a mounting configuration of a process cartridge.

FIG. 5 is an explanatory diagram of a mounting configuration of a process cartridge.

FIG. 6 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

A: image forming apparatus, B: process cartridge, 1: optical system, 2: recording medium, 3: conveying means, 4: transfer roller,
Reference numeral 5: fixing means, 6: discharging section, 7: photosensitive drum, 8: charging roller, 9: exposure section, 10: developing means, 10a: toner feeding member, 10b: magnet, 10c: developing roller, 10d: developing blade , 11 cleaning means, 11a cleaning blade, 11b squeeze sheet, 11c ... waste toner reservoir, 12
... 1st frame, 13 ... 2nd frame, 13a ... insertion hole, 13b ... shaft hole, 14 ... apparatus main body, 15 ... opening / closing member, 15a ... shaft, 16 ... guide member, 16a ... guide part, 17 ... drum gear , 17a: shaft hole, 17b: hollow portion, 17c: cylindrical portion, 18: flange gear,
18a: Shaft, 19: Drive gear, 20: Metal shaft, 21: Reinforcing member

Continuation of the front page (56) References JP-A-5-2977781 (JP, A) JP-A-6-130874 (JP, A) JP-A-6-89069 (JP, A) (58) Fields studied (Int) .Cl. ⁷ , DB name) G03G 21/18

Claims (5)

(57) [Claims] 1. An electrophotographic photosensitive drum used for a process cartridge detachable from a main body of an image forming apparatus, comprising: a cylinder having a photosensitive member on a surface; and a cylinder made of a synthetic resin material provided at one end in an axial direction of the cylinder. A shaft hole provided in the drum gear, which fits with a shaft provided in a cartridge frame of the process cartridge, wherein the electrophotographic photosensitive drum is rotatable with respect to the cartridge frame. A shaft hole for supporting; a lightening portion provided between the shaft hole and the tooth bottom of the drum gear; and a reinforcing member made of the same material as the drum gear and pressed into the lightening portion. And a reinforcing member for suppressing deformation of the tooth surface of the drum gear. 2. The electrophotographic photosensitive drum according to claim 1, wherein the reinforcing member has a cylindrical shape, and an inner diameter portion of the reinforcing member is press-fitted into the hollow portion. 3. A process cartridge detachable from a main body of an image forming apparatus, comprising: a cylinder having a photosensitive member on a surface thereof; and a drum gear made of a synthetic resin material and provided at one axial end of the cylinder. A photosensitive drum; at least one process unit acting on the electrophotographic photosensitive drum; a cartridge frame; a shaft provided in the cartridge frame; and a shaft hole provided in the drum gear to be fitted with the shaft. A shaft hole for rotatably supporting the electrophotographic photosensitive drum with respect to the cartridge frame, a hollow portion provided between the shaft hole and a tooth bottom of the drum gear, A reinforcing member made of the same material as the drum gear and pressed into the lightening portion, the reinforcing member being configured to suppress deformation of a tooth surface of the drum gear; A process cartridge which is characterized in that. 4. The process cartridge according to claim 3, wherein the reinforcing member has a cylindrical shape, and an inner diameter portion of the reinforcing member is press-fitted into the hollow portion. 5. An image forming apparatus in which a process cartridge is detachable and which forms an image on a recording medium, comprising: a cylinder having a photosensitive member on a surface; and a cylinder made of a synthetic resin material, provided at one end in the axial direction of the cylinder. An electrophotographic photosensitive drum having a set drum gear, at least one process means acting on the electrophotographic photosensitive drum, a cartridge frame, a shaft provided on the cartridge frame, and fitting with the shaft. A shaft hole provided in the drum gear, the shaft hole for rotatably supporting the electrophotographic photosensitive drum with respect to the cartridge frame, and a shaft hole between the shaft hole and a tooth bottom of the drum gear. And a reinforcing member made of the same material as the drum gear and press-fitted into the lightening portion, which suppresses deformation of the tooth surface of the drum gear. An image forming apparatus comprising: the order of the reinforcing member, and mounting means for detachably mounting a process cartridge having a conveying means for conveying the recording medium.