JP2000267505A - Photoreceptor drum, process unit using the photoreceptor drum and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to facilitate the processing of a metallic weight member and the assembly work of inserting the weight member into a drum body, to stably support the inserted weight member by a simple constitution and to cost effectively form the photosensitive layer of the drum body. SOLUTION: This photoreceptor drum includes the drum body 21 of a cylindrical body which is opened at both ends and is formed with the photosensitive layer 22 on its outer peripheral surface, a pair of end members 23 and 24 which are respectively fitted into both end open parts of the drum body 21 and the metallic weight member 26 which is inserted into the drum body 21 and is formed to a columnar body arranged in the state of not coming into contact with the inner peripheral surface of the drum body 21 on the central axis of the drum body. Further, the metallic weight member 26 is supported a supporting member for press-fitting the metallic weight member into the drum body 21. The supporting member is supported by the end members 23 and 24 disposed at the open ends of the drum body 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum used in an electrophotographic apparatus, a process unit using the photosensitive drum, and an electrophotographic apparatus.

[0002]

2. Description of the Related Art An electrophotographic apparatus forms an electrostatic latent image on a photosensitive member and transfers a toner image obtained by developing the electrostatic latent image to recording paper. It is used for an image recording unit in an image forming apparatus. A photoreceptor provided in the electrophotographic apparatus generally uses a photoreceptor drum, and the photoreceptor drum includes a drum main body formed of a metal cylinder having a photosensitive layer formed on an outer peripheral surface.

The drum body of this photosensitive drum is made of aluminum and its alloys in order to meet various photoconductive characteristics and requirements for processing accuracy such as roundness, straightness, and runout accuracy. For example, an outer diameter of 60 mm,
Although the drum body made of aluminum having a length of 240 mm and a thickness of 1 mm weighs about 120 g, a sufficient curvature and moment of inertia are provided so as to avoid a problem that occurs between each process device around the photosensitive drum. ,
In addition, it is possible to reduce the occurrence of vibration, uneven rotation, noise, and the like during rotation.

Recently, it has been required to reduce the outer diameter of the photosensitive drum for reasons such as miniaturization, weight reduction, and cost reduction of the electrophotographic apparatus, and in order to reduce the amount of expensive aluminum used. There is a growing demand for thinner photoreceptor drums. However, when the outer diameter is reduced and the wall thickness is reduced in this manner, the weight of the photoconductor drum is reduced and the moment of inertia is reduced, so that the driving stability of the photoconductor drum itself is reduced and the charging device in the process unit is reduced. In addition, problems such as generation of minute vibrations in portions related to processes such as an exposure device and a development device, occurrence of image unevenness, generation of abnormal sound, and the like occur. In addition, the curvature of the photosensitive drum is reduced, and the margin of the contact accuracy is reduced in a portion where the photosensitive drum and another process device are in contact with each other.

[0005] In order to increase the weight and increase the moment of inertia of the photosensitive drum, the weight of which is reduced by reducing the outer diameter and the wall thickness to reduce the weight and thus reducing the moment of inertia. A weight member is provided inside a main body. Conventionally, a type in which a weight member made of metal or rubber is tightly fixed to the inner peripheral surface of the drum main body inside the drum main body has been adopted.

FIG. 6 is a sectional view showing a photosensitive drum provided with a weight member made of metal inside the drum body. In FIG. 1, reference numeral 1 denotes a drum body which is a cylindrical body made of aluminum and whose both ends are open, and has a photosensitive layer 2 formed on the outer peripheral surface.
Reference numeral 3 denotes a column-shaped metal weight member made of, for example, stainless steel, and reference numerals 4 and 5 denote a pair of end members. The metal weight member 3 has a length smaller than the length of the drum body 1 and is press-fitted into the center of the inside of the drum body 1, and its outer peripheral surface is in contact with the inner peripheral surface of the drum main body 1. The metal weight member 3 is fixed to the inside of the drum main body 1 by press-fitting, and is further adhered and fixed to the drum main body 1 using an adhesive. For example, a metal weight member 3 having an outer diameter of 22.4 mm is press-fitted inside a drum body 1 having an outer diameter of 24 mm and an inner diameter of 22.4 mm. The pair of end members 4 and 5 are fitted into open ends of the drum body 1 at both ends and fixed by means such as bonding. In this photosensitive drum, for example, a core shaft 7 is individually provided on a pair of end members 4 and 5, respectively.

FIG. 7 is a sectional view showing a photosensitive drum in which a rubber weight member 6 is press-fitted inside the drum main body 1, and the same parts as those in FIG. 6 are denoted by the same reference numerals. The rubber weight member 6 has a length smaller than the length of the drum body 1 and is press-fitted into the center of the inside of the drum body 1, and its outer peripheral surface contacts the inner peripheral surface of the drum main body 1 and is fixed in a press-fit state. Are fixed by bonding. In this photoconductor drum, one core shaft 8 is provided so as to penetrate the end members 4 and 5 and the rubber weight member 6 in common.

[0008]

The above-mentioned conventional photosensitive drum has the following problems. The type using the metal weight member 3 has the following problem. In order to press-fit the metal weight member 3 smoothly into the drum body 1 and fix it, a predetermined outer diameter accuracy is required, high precision processing technology and high cost are required, and the metal weight member 3 is Drum body 1
In order to press-fit the drum main body 1 with high accuracy when press-fitting the drum body 1, a high-precision assembly technique and high cost are required.

The work of press-fitting the metal weight member 3 into the inside of the drum body 1 needs to be performed before the step of forming the photosensitive layer 2 on the outer peripheral surface of the drum body 1 due to workability. . Therefore, the weight member press-fitting step is performed in a step before forming the photosensitive layer 2 on the drum main body 1. Therefore, the weight of the drum main body 1 loaded with the metal weight member 3 is increased and the photosensitive layer 2 is processed. Is formed, which hinders the photosensitive layer forming step. For example, the photosensitive layer 2 is formed by a coating method.
Is formed, a heavy drum body becomes a heavy burden on each working machine in the coating process. Also,
When the photosensitive layer 2 is formed by the pull-up coating method, an increase in the weight of the drum body makes it difficult to control the pull-up speed, which greatly affects the quality of the photosensitive layer 2. further,
When the metal weight member 3 is fixed with an adhesive, the temperature of the drum body increases when the photosensitive drum is used,
The adhesive adversely affects the photosensitive layer 2 made of a chemical substance when the photosensitive drum is stored for a long period of time and with changes in the environment.

The type using the rubber weight member 6 has the following problem. Since the rubber weight member 6 has a specific gravity as small as 1 or 2 as compared with the metal weight member, a member having a larger volume than the metal weight member is required to secure the required weight and moment of inertia. As a result, the material cost is increased, and a sophisticated press-fitting technique is required, which increases the manufacturing cost. When the rubber weight member 6 is press-fitted and fixed inside the drum main body 1, it is necessary to increase the press-fitting pressure in order to prevent the weight member from shifting in the axial direction. Increased rubber weight member 6
It is difficult to increase the press-fitting pressure. As described above, in order to require a high technique for press-fitting the rubber weight member 6, it is necessary to perform the press-fitting operation of the weight member before forming the photosensitive layer as in the case of the metal weight member. The same problem as that of the member occurs. When the rubber weight member 6 is bonded and fixed inside the drum main body 1, the above-described problem caused by press-fitting can be avoided. However, as in the case of the metal weight member, the adhesive adversely affects the photosensitive layer. This causes a chemical change such as corrosion between the rubber and the adhesive, which makes it difficult to bond and fix the rubber weight member 6 to the drum body 1. Also, in order to increase the moment of inertia as the outer diameter of the drum body 1 decreases, it is necessary to increase the volume of the rubber weight member 6 to increase the weight. In some cases, even if the inside of the drum body 1 is filled with the rubber weight member 6, the required effect may not be sufficiently obtained.

Therefore, for the photosensitive drum provided in the electrophotographic apparatus, it is easy to process the weight member to be inserted into the drum body and to assemble the weight member into the drum body. It has been demanded that the weight member can be stably supported with a simple configuration, exhibit performance as a weight member, and that a high-quality photosensitive layer can be economically formed on the drum body.

The present invention has been made in view of the above circumstances, and is easy to process the weight member and to assemble the weight member into the drum main body, and to stably insert the inserted weight member with a simple configuration. It is an object of the present invention to provide a photosensitive drum which can be supported, is excellent in economical efficiency, can economically form a photosensitive layer of the drum main body, and solves a conventionally required problem.

An object of the present invention is to provide a process unit and an electrophotographic apparatus provided with the above-mentioned photosensitive drum.

[0014]

According to a first aspect of the present invention, there is provided a photosensitive drum having a cylindrical body having both ends opened and a photosensitive layer formed on an outer peripheral surface; A pair of end members fitted respectively, and a column-shaped metal weight member inserted into the drum main body and arranged on the drum main body central axis so as not to contact the inner peripheral surface of the drum main body. It is characterized by having.

According to the structure of the present invention, a metal weight member having a necessary weight as a metal weight member can be processed without being strictly restricted by processing accuracy, and the metal weight member is disposed inside the drum body. Easy insertion without press fit. In addition, the photosensitive layer can be formed on the drum main body before the metal weight member is inserted, so that workability and economic efficiency in forming the photosensitive layer can be improved.

The photosensitive drum according to the second aspect of the present invention has a cylindrical body having both ends opened and a photosensitive layer formed on the outer peripheral surface, and is fitted and fixed to both ends of the drum body. A pair of end members, a metal weight member having a columnar shape, which is inserted into the inside of the drum body and is arranged on the center axis of the drum body so as not to contact the inner peripheral surface of the drum body; and And a pair of support members disposed inside and fixed between the end member and both ends of the metal weight member to support both ends of the metal weight member.

According to a third aspect of the present invention, in the photosensitive drum according to the second aspect, the pair of end members support the pair of support members.

According to a fourth aspect of the present invention, in the photosensitive drum according to the second aspect, the pair of support members engage with both ends of the metal weight member to support the metal weight member. And

According to the construction of the second to fourth aspects of the present invention,
The metal weight member inserted into the inside of the drum body can be stably supported with a simple configuration so as to exhibit the performance as the metal weight member.

According to a fifth aspect of the present invention, there is provided the photosensitive drum according to any one of the second to fourth aspects, wherein the drum main body, the metal weight member, the pair of end members, and the pair of support members are combined. Moment (gcm)
Satisfies 7.22 ≦ I ≦ 461.

According to the present invention, in the configuration in which the metal weight member is provided on the drum main body, the photosensitive drum can be stably rotated so that a good image can be formed, and an excessive load is applied to the rotary drive system. Can provide a photoconductor drum without any.

According to a sixth aspect of the present invention, there is provided a process unit including the photosensitive drum according to any one of the first to fifth aspects, and a cleaning device for removing toner remaining on the photosensitive surface of the photosensitive drum. .

According to the configuration of the present invention, it is possible to obtain an economical and excellent process unit having a photosensitive drum.

According to a seventh aspect of the present invention, there is provided an electrophotographic apparatus comprising: a photosensitive drum according to any one of the first to fifth aspects; a developing device for storing a toner for forming a toner image on the photosensitive drum; It is characterized by having.

According to the structure of the present invention, it is possible to obtain an economical and excellent electrophotographic apparatus having a photosensitive drum.

[0026]

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

FIG. 1 illustrates an embodiment of an electrophotographic apparatus using the photosensitive drum of the present invention, with reference to FIG. The electrophotographic apparatus is provided in an image forming apparatus such as a facsimile apparatus and a printer. FIG. 1 is a sectional view showing a schematic configuration of the electrophotographic apparatus. In FIG. 1, reference numeral 11 denotes a rotatable photosensitive drum, which is rotated in a direction indicated by an arrow by a rotation driving mechanism provided on an apparatus main body of an image forming apparatus (not shown). The photoconductor drum 11 will be described later. A scorotron-type charging device 12, an exposing device 13, a developing device 14, a scorotron-type transfer device 15, and a cleaning device 16 are provided around the photoconductor drum 11 in this order along the rotation direction of the photoconductor drum 11.

The charging device 12 charges the photosensitive layer formed on the outer peripheral surface of the photosensitive drum 11, and the exposure device 13 forms an electrostatic latent image on the photosensitive layer of the photosensitive drum 11. Developing device 14
Is a toner container 17 containing a one-component toner T, and a developing roller 1 for applying the toner 1 to the electrostatic latent image formed on the photosensitive layer of the photosensitive drum 11 to form the toner image.
8 and a toner supply roller 19 for supplying the toner T stored in the toner container 17 to the developing roller 18. The transfer device 15 transfers the toner image formed on the photosensitive layer of the photosensitive drum 11 to the recording paper P. Cleaning device 1
In 6, the polyurethane blade 16 a is slid in contact with the photosensitive layer of the photosensitive drum 11 to remove toner and foreign substances that have not been transferred to the photosensitive layer of the photosensitive drum 11. In this embodiment, the photoreceptor drum 11, the charging device 12, the developing device 14, and the cleaning device 16 are collectively integrated as one unit by appropriate means to constitute a process unit A. The photoconductor drum 11 is rotatably supported by a frame of an appropriate device constituting the process unit A. The process unit A is detachably mounted on the apparatus main body of the image forming apparatus.

Next, an embodiment of the photosensitive drum 11 used in the electrophotographic apparatus will be described. Photoconductor drum 1
A first embodiment will be described with reference to FIG. In FIG. 2, reference numeral 21 denotes a drum body made of an excellent metal, for example, aluminum, which is made of a cylinder having both conductivity and open at both ends for workability and the like.
The photosensitive layer 22 composed of, for example, three layers is formed on the entire outer peripheral surface of the drum main body 21 by a pull-up coating method.
For example, the drum body 21 has an outer diameter of 20 mm and an inner diameter of 18.4 m
m, length 249 mm.

Reference numerals 23 and 24 denote a pair of circular end members made of hard plastic.
And a flange having an outer diameter larger than the outer diameter of the drum main body, while having a diameter capable of being press-fitted to both open ends. The flange of one end member 23 is gear 2
5 is formed. These pair of end members 23,
Reference numeral 24 is press-fitted to both open ends of the drum main body 21, and respective flanges are located outside the drum main body 21. The end members 23 and 24 are formed with shaft holes 23a and 24a penetrating on the central axis.

Reference numeral 26 denotes a metal weight member, which forms a columnar body made of, for example, cast iron whose surface is nickel-plated. The metal weight member 26 is attached to the drum main body 21.
The weight of the drum main body 21 is increased to compensate for the weight of the drum main body 21, thereby increasing the moment of inertia of the drum main body 21. The metal weight member 26 is inserted into the inside of the drum main body 21, is positioned on the center axis of the drum main body, and is disposed at a central portion in the axial direction without contacting the inner peripheral surface of the drum main body 21. The diameter is set sufficiently smaller than the inner diameter of the drum main body 21 so as not to contact the inner peripheral surface of the drum 21, and the length is set so that a volume having a necessary weight can be obtained.

Reference numerals 27 and 28 denote a pair of support members, which are made of, for example, "neoprene rubber". The pair of support members 27 and 28 are press-fitted into the drum main body 21 to support the metal weight member 26, and have a diameter capable of being press-fitted into the drum main body 21. The pair of support members 27 and 28 are provided inside the drum body 21 at both ends of the metal weight member 26 (both ends of the metal weight member 26 and each end member 2).
3 and 24), and presses toward the center by abutting on both end surfaces of the metal weight member 26 located on the center axis of the drum body and located at the center in the axial direction. By doing so, the metal weight member 26 is sandwiched and supported at both ends. As a result, the metal weight member 26 is supported by the pair of support members 27 and 28 on the drum main body 21 without contacting the inner peripheral surface.

Reference numerals 29 and 30 denote core shafts made of, for example, a conductive metal. The core shafts 29, 30 have a length greater than the axial length of the end members 23, 24,
End members 23 and 24 are inserted and fixed in shaft holes 23a and 24a. Thereby, the pair of core shafts 29 and 30 are provided integrally with the end members 23 and 24. A pair of core shafts 29, 3
For 0, a material having conductivity at least one of which is used for grounding with respect to the ground, or a material having conductivity given by mixing carbon powder or the like is used. Therefore, one core shaft 30 is electrically connected to the drum main body 21 by the ground member 32. The ends of the core shafts 29 and 30 projecting outward from the pair of end members 23 and 24 are rotatably supported by bearings (not shown) provided in the process unit A. A gear 25 formed on a flange of one end member 23
Is provided so as to mesh with a rotation transmission gear (not shown) provided in a rotation driving device provided in the apparatus main body, and that the rotation of the rotation transmission gear causes the entire photosensitive drum to rotate.

A method for manufacturing the photosensitive drum 11 having the above-described structure will be described. First, three photosensitive layers 22 are formed on the outer peripheral surface of the drum main body 21 by a pulling method.
That is, the photosensitive layer 22 has an undercoat layer as a first layer, a charge generation layer and a third double charge transport layer as a second layer. The undercoat layer was formed by applying a conductive paint (manufactured by Kansai Paint Co., Ltd.) in which carbon particles were mixed in a binder and a solvent of a synthetic resin so as to have a dried film thickness of 70 μm. In the present invention, the material of the undercoat layer is a material in which a coating film can be formed with a coating material in which a powder of a metal such as aluminum, brass or nickel, a powder of carbon black or tin oxide is dispersed in an acrylic resin, a phenol resin or the like. Any material may be used, and those having a resistivity of about 10 ⁶ to 10 ¹² are particularly preferable.
The charge generation layer was prepared by mixing τ-type metal-free phthalocyanine and polyvinyl butyral at a ratio of 1: 1 in synchrohexane, and then mixing the mixture with a ball mill for 24 hours.
It was applied to a thickness of 2 μm. The charge generation layer in the present invention may be any layer that can generate charges with high efficiency by absorbing light. The charge transport layer is formed by dissolving N-ethylcarbazole-3-carboxyadehydridomethylphenylhydrazone, which is a hydrazone compound, and pyricarbonate in 1,1,2-trichloromethane at a weight ratio of 1: 1 to form a uniform solution, and drying the solution. Thereafter, the film was coated so as to have a thickness of 20 μm. The charge transport layer in the present invention may be any material as long as a substance having a charge transport function is dissolved in an organic solvent at a predetermined ratio together with a suitable polymer compound to form a coatable uniform solution. If you choose one with a charge transport function. The charge transport material may be added in a smaller amount or not added at all.

After the photosensitive layer 22 is formed on the outer surface of the drum main body 21 as described above, the metal weight member 26 and the pair of support members 27 and 28 are inserted into the drum main body 21 and the pair of end members 23 are formed. , 24 are press-fitted to both open ends of the drum body 21.

The photosensitive drum 11 of the present invention has the following effects. A structure in which a metal weight member 26 is inserted into the inside of the drum main body 21 so as to add weight to the drum main body 11, and is sandwiched between the pair of support members 27 and 28 so as to be supported so as not to contact the inner peripheral surface of the drum main body 21. Therefore, the metal weight member 26 is pressed into the inside of the drum main body 21 (in a state where the outer peripheral surface of the metal weight member is in contact with the inner peripheral surface of the drum main body 21). The processing accuracy is greatly reduced in processing the material, the processing of the weight member is facilitated, and the processing cost can be significantly reduced. Metal weight member 2
6 having a pair of support members 2 inserted inside the drum body 21.
7 and 28, the metal weight member 26
The metal weight member 26 can be easily supported, and the metal weight member 26 is inserted into and supported by the drum body 21 as compared with the case where the metal weight member 26 is pressed into the inside of the drum main body 21 or fixed with an adhesive. The assembly method is simple and economical.

Since a metal weight member is used as a weight member for imparting weight to the drum body 11, a smaller and larger weight can be obtained as compared with a case where a weight member made of rubber is used. .

Further, the metal weight member 26 is connected to the drum body 2.
Since the photosensitive drum 22 is formed on the outer peripheral surface of the drum body 21 after the photosensitive layer 22 is formed on the outer peripheral surface of the drum body 21, The metal weight member 26 and the pair of support members 27 and 28 can be inserted into the drum main body 21 and assembled. Therefore, even if a defect is found in the photosensitive layer 22 when the photosensitive layer 22 is formed on the drum main body 21, since this is a stage before the metal weight member 26 is incorporated into the drum main body 21, the drum main body 21 is discarded. It is possible to minimize the economic loss caused by the occurrence of defects. However, if the photosensitive layer is formed on the drum body after the weight member is incorporated, if the photosensitive layer becomes defective, both the drum body and the weight member must be discarded, which is economical. The loss is very large.

Further, the drum body 21, the metal weight member 2
6, a pair of end members 23 and 24 and a pair of support members 2
The moment of inertia (g · cm) of the photoreceptor drum obtained by combining Nos. 7 and 28 was in the range of 7.22 ≦ I ≦ 461, and as a result, a good moment of inertia was obtained.

The process unit A having the photosensitive drum 11 is very economical and can be driven stably to record a good image.

FIG. 3 shows a second embodiment, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In this embodiment, a pair of support members are supported by a pair of end members. In the figure, reference numerals 271 and 281 denote a pair of support members. The pair of support members 271 and 281 are longer than the support member 27 shown in FIG. A pair of end members 2 fitted to the parts
The other end face is pressed against the end face of the metal weight member 26 at the same time. As a result, the pair of end members 23 and 24 are
1 and 281, and a pair of support members 271, 28
Numeral 1 supports and fixes the metal weight member 26, and can fix the metal weight member 26 with a simple configuration while preventing displacement (lateral displacement) in the axial direction. A shaft hole 26a is formed on the metal weight member 26 on the center axis, and a pair of support members 271 and 281 are formed with shaft holes 271a and 281a. The shaft hole 26a of the metal weight member 26, the shaft holes 271a, 281a of the pair of support members 271, 281 and the shaft holes 23a, 24a of the pair of end members 23, 24 have a length greater than the length of the drum body 21. The core shaft 31 having a height is inserted. The core shaft 31 includes at least a pair of end members 2.
The drum main body 21 and the core shaft 31 are fixed to the shaft holes 23a, 24a of the pair 3 and 24, and the pair of end members 23, 24
Are united through. A pair of support members 271, 2
The material 81 is made of a material having conductivity at least one of which is grounded with respect to the ground, or a material provided with conductivity by mixing carbon powder or the like.

Here, the metal weight member 26 is formed of nickel-plated cast iron, and a pair of support members 27 are provided.
1, 281 are formed of "ABS resin".
It is desirable that the pair of support members 271 and 281 be made of the same material in order to maintain the weight balance of the drum main body 21. When both of the support members 271 and 281 have conductivity, both or one of them, and when one of them has conductivity, the conductive member comes into contact with the core shaft 31 and is connected to the ground. ing. In this embodiment, for example, the drum main body 21 has a length of 249 mm and an outer diameter of 2 mm.
0 mm, inner diameter 18.4 mm.

FIG. 4 shows a third embodiment, which is based on the second embodiment, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In this embodiment, the metal weight member 26 of the pair of support members 271 and 281 is used.
Recesses 271b, 281b having dimensions so that the end of the metal weight member 26 can be engaged with the end face facing the side without play.
And the ends of the metal weight member 26 are engaged with the concave portions 271b and 281b. With this configuration, the metal weight member 26 can prevent displacement in the radial direction in addition to preventing displacement in the axial direction, and can be more strongly supported by the pair of support members 271 and 281. Here, the metal weight member 26 is formed of nickel-plated cast iron, and the pair of support members 271 and 281 are formed of “conductive urethane foam”. In this embodiment, for example, the drum main body 21 has a length of 246 mm,
The outer diameter is 16 mm and the inner diameter is 14.4 mm.

FIG. 5 shows a fourth embodiment. In FIG. 5, the same parts are denoted by the same reference numerals. In this embodiment, a projection is formed on a pair of support members to support a metal weight member. In FIG. 5, 2
Numeral 61 denotes a metal weight member, and concave portions 26 are provided on both end surfaces thereof.
1a is formed. Reference numerals 272 and 282 denote a pair of support members. The protruding portions 2 which are engaged with the concave portions 261a without backlash on end surfaces of the metal weight members 261 facing the end surfaces.
72b and 282b are formed respectively. With this configuration, the metal weight member 261 prevents the displacement in the radial direction in addition to the displacement in the axial direction, and more firmly supports the pair of support members 27.
2, 282 can be supported. In this embodiment, the metal weight member 261 does not have an axial hole, and the pair of support members 272 and 282 are located on the central axis and do not penetrate the metal weight member side. Shaft holes 272a and 282a are formed. A pair of core shafts 2
9, 30 are shaft holes 23a, 2 of a pair of end members 23, 24;
4a and the shaft holes 272a of the pair of support members 272, 282,
282a. Here, the metal weight member 26 is formed of nickel-plated cast iron, and the pair of support members 271 and 281 are formed of “fluororubber”.

The drum main body 21 is not limited to the material described in the above embodiment, but may be formed of a metal material such as brass, stainless steel, iron, or copper, in addition to aluminum. In addition to metals, conductive resins, paper subjected to a conductive treatment, glass, and the like can also be mentioned, and those capable of performing predetermined processing can be used. The metal weight member is not formed of the material and shape described in the above-described embodiment, and may be any material that can obtain a predetermined weight and moment of inertia with respect to the drum main body. The material of the pair of support members is not limited to synthetic resin, rubber, and foam, and it is possible to employ a combination of these materials and the like. And various conductive treatments can be employed.

Here, a running test was repeatedly performed on the electrophotographic apparatus shown in FIG. 1 incorporating the photosensitive drum of the present invention. The specific conditions are as follows: 3000 sheets of A4 length at environmental conditions of 23 ° C. and 50% humidity, and 3000 sheets of A4 length at environmental conditions of 10 ° C. and 20% humidity.
3,000 sheets of A4 size at 35 ° C. and 80% humidity under environmental conditions and 1000 sheets of A4 length at a temperature of 23 ° C. and 50% humidity were again performed on 5% character images. Then, the moment of inertia, the jitter in the sub-scanning direction, the time until a drive failure occurs, and the occurrence of abnormal cleaner blade noise were examined. The drive failure is a failure of a mechanism for rotating and driving the photosensitive drum, and the occurrence of abnormal noise of the cleaner blade means the occurrence of abnormal noise in the cleaner blade for removing the residual toner on the photosensitive drum.

Table 1 shows the experimental results. Embodiments 1 to 13 are directed to the present invention. In this table, Example 7 is the format shown in FIG. 2 of the present invention, and Example 8 is the format shown in FIG.
, The ninth embodiment is the format shown in FIG. 4, and the eleventh embodiment is the format shown in FIG. As a result of the experiment, in each embodiment, there was no phenomenon such as uneven image pitch in the sub-scanning direction and image omission, and there was no problem such as abnormal noise, abnormalities, breakage, etc. in cleaning blades and other process-related devices. Images were obtained, and all passed the comprehensive judgment. Comparative Examples 1 to 5 had the conventional configuration shown in FIG. 6 or 7, and all of them were defective in the overall judgment.

[0048]

[Table 1]

The photosensitive drums of the first to thirteenth embodiments to which the present invention is applied all have a moment of inertia (g · cm).
Is within the range of 7.22 ≦ I ≦ 461, and all of the photosensitive drums of Comparative Examples 1 to 5 have a moment of inertia (g · c).
m) did not fall within the above range. That is, when the moment of inertia (g · cm) satisfies 7.22 ≦ I, a sufficient moment of inertia cannot be obtained on the photosensitive drum, and stable rotation cannot be performed. And an abnormal sound caused by a minute vibration of the contact point between the cleaning blade and the surface of the photosensitive drum in a low temperature and low humidity environment. When the moment of inertia (g · cm) is 1 ≦ 461, the moment of inertia of the photoconductor drum was sufficient, but the weight of the photoconductor drum itself was too heavy. Before the driving is achieved, the driving relationship will be extremely overloaded,
The drive system did not operate normally, and abnormal noise and damage due to the applied load occurred, and it was impossible to maintain the original functions in a normal state from beginning to end.

Thus, the structure in which the metal weight member is provided on the drum main body can stably rotate the photosensitive drum so that a good image can be formed, and can prevent the photosensitive drum from exerting an excessive load on the rotation drive system. You can get a body drum.

As a remarkable example, a photosensitive drum composed of a drum body having an outer diameter of 16 mm, an inner diameter of 14.3 mm, and a length of 256 mm, and having no weight member inside the drum body, has an uneven image pitch from the beginning. Occurred, and an abnormal noise was generated by the cleaning blade. The only way to eliminate the abnormal noise is to sacrifice the cleaning performance of the photosensitive drum, and it is difficult to eliminate the abnormal noise while maintaining the cleaning performance. In contrast, the photosensitive drum of the present invention was able to eliminate abnormal noise while maintaining the cleaning performance of the photosensitive drum.

[0052]

According to the first aspect of the present invention, since the metal weight member forming the cylindrical body is inserted into the drum main body of the photosensitive drum and arranged so as not to contact the inner peripheral surface of the drum main body, A metal weight member having a necessary weight as a weight member can be processed without being strictly restricted by processing accuracy.
In addition, the metal weight member can be easily inserted into the inside of the drum body without press-fitting, and the metal weight member inserted into the drum body can be stably supported with a simple configuration. In addition, the assembly in which the weight member is inserted into the inside of the drum body can be facilitated, and the economy can be improved. Also,
The invention according to claims 2 to 4, wherein a photosensitive layer can be formed on the drum main body before the metal weight member is inserted into the inside of the drum main body, and workability and economic efficiency in forming the photosensitive layer can be improved. In addition to the effects of the first aspect, the metal weight member inserted into the inside of the drum body can be stably supported with a simple configuration so that the performance as the weight member can be exhibited.

According to the fifth aspect of the present invention, in addition to the effects described in the second to fourth aspects, in the configuration in which the metal weight member is provided on the drum main body, the photosensitive drum is stable so that a good image can be formed. The photosensitive drum can be provided without rotating the rotating drive system while applying an excessive burden to the rotating drive system.

According to the sixth aspect of the present invention, it is possible to obtain a process unit having the economical and excellent photosensitive drum according to the first to fifth aspects.

According to the seventh aspect of the present invention, it is possible to obtain an electrophotographic apparatus having the economical and excellent photosensitive drum according to the first to fifth aspects.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an electrophotographic apparatus.

FIG. 2 is a cross-sectional view illustrating a photosensitive drum according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a photosensitive drum according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a photosensitive drum according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a photosensitive drum according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a conventional photosensitive drum.

FIG. 7 is a cross-sectional view illustrating a configuration of a conventional photosensitive drum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Photoreceptor drum, 21 ... Drum main body, 22 ... Photosensitive layer, 23 ... End member, 24 ... End member, 25 ... Gear, 26 ... Metal weight member, 27 ... Support member, 28 ... Support member, 29 ... core shaft, 30 ... core shaft, 31 ... core shaft, 261 ... metal weight member, 271 ... support member, 281 ... support member, 272 ... support member, 282 ... support member, A ... process unit.

Claims (7)

[Claims] 1. A drum body having a cylindrical body with both ends open and having a photosensitive layer formed on the outer peripheral surface, a pair of end members fitted and fixed respectively to both ends of the drum body, and the drum A photosensitive weight drum having a columnar metal weight member inserted into the body and arranged on the center axis of the drum body so as not to contact the inner peripheral surface of the drum body. 2. A drum body having a cylindrical body open at both ends and having a photosensitive layer formed on an outer peripheral surface thereof; a pair of end members respectively fitted to open ends of the drum body; A metal weight member having a columnar shape inserted inside the drum main body and arranged on the drum main body axis line so as not to contact the inner peripheral surface of the drum main body, and the pair of end members inside the drum main body and the A photoconductor drum, comprising: a pair of support members disposed between and fixed to both ends of the metal weight member and supporting both ends of the metal weight member. 3. The photosensitive drum according to claim 2, wherein the pair of end members support the pair of support members. 4. The photosensitive drum according to claim 2, wherein said pair of support members engage with both ends of said metal weight member to support said metal weight member. 5. A combination of the drum body, the metal weight member, the pair of end members and the pair of support members has a moment of inertia (g · cm) of 7.22.
≤I≤461
The photosensitive drum according to any one of the above. 6. A process unit comprising: the photosensitive drum according to claim 1; and a cleaning device that removes toner remaining on a photosensitive surface of the photosensitive drum. 7. An electronic device comprising: the photosensitive drum according to claim 1; a developing device that stores toner for forming a toner image on the photosensitive drum; and a transfer device. Photo equipment.