JPS6138963A - Photosensitive drum for electronic copying machine - Google Patents

Abstract

PURPOSE:To improve heat radiation and to obtain a uniform surface temperature over the whole drum length by inserting plural corrugate fins differently waved in respective sectional directions between radical rims arranged between an inner cylinder for a bearing and a drum body in the axial direction and fixing the fins. CONSTITUTION:The inner cylinder 2 for the bearing and the outer cylinder 1 forming the drum body are concentrically and unitedly molded through plural radical coupling rims 3 and the plural kinds of fins 4 which are corrugate fins 4 waved with the different number of waves in their sectional directions are successively inserted between the rims 3 arranged between the inner and outer cylinders l, 2 in the axial direction so that both the leading end surfaces 4a in the height direction of the fins 4 are abutted upon the outer and inner peripheries of the inner and outer cylinders 1, 2, the abutted part 4a is unitedly joined and fixed and the fin pitches are gradually increased in the direction from one end of the cooling air inflow side of the drum to the other end. Said constitution makes it possible to improve the heat radiation of the photosensitive drum and reduce the surface temperature sufficiently over the whole length by ventiration from one end of the drum to keep it uniformly. In addition, a fixing mechanism can be simplified and a copying machine can be reduced at its size.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electrostatic photosensitive drum used in an electronic copying machine applying electrophotography, and more specifically, to an electrostatic photosensitive drum having a photosensitive layer whose outer peripheral surface is coated with a transparent insulating layer. The present invention relates to a drum-shaped photoreceptor made of a conductive support.

(Prior Art) Conventionally, this type of photosensitive drum uses a hollow cylinder made of metal such as aluminum and having a photosensitive layer formed on its outer peripheral surface. In order to rotationally support this, a pair of separately formed flange members is applied to both ends of the cylinder,
These are fastened with a plurality of fastening bolts to be integrated with the cylinder, and are removably supported on the drum shaft via a bearing such as a ball bearing attached to a flange member.

(Problems with the prior art) Therefore, in the conventional photosensitive drum as described above, in addition to the cylinder, a pair of flanges, bearings, etc. are separately required to support the drum, which increases the number of parts. Not only does this complicate the structure and increase costs, but it also helps if the cylinder needs to be replaced due to fatigue or damage to the photoconductor.
It has the disadvantage that it requires a complicated procedure for attachment and detachment, which requires a lot of effort.

In addition, in the rotational support of the photosensitive drum, the cylinder is supported on the drum shaft via a separate flange and bearing, so the center of the cylinder may be distorted due to the accumulation of errors between each member. Sometimes the center of the drum does not exactly match the center of the drum shaft over its entire length, which can have various adverse effects on the copying function.

Furthermore, in recent years, there has been an increasingly strong demand for miniaturization of electronic copying machines, and accordingly, photosensitive drums are also becoming smaller. In addition, after an image is transferred to a transfer paper by a photosensitive drum, the heating and fixing operation of the developed image electrostatically adhered to the transfer paper is performed around the photosensitive drum, which makes it easier to install a fixing section separately. Attempts have also been made to reduce space. However, when a photosensitive drum is heated by a corona discharger or a lamp and in addition a heating fixing roll is placed closely around its circumference, its temperature tends to increase. Conventional photosensitive drums as described above have poor heat dissipation properties, which, combined with the tendency for surface area to decrease due to miniaturization of the drum itself, tends to cause overheating of the drum, resulting in a significant decline in the charging performance of the photosensitive drum. Alternatively, problems arise in that the toner melts on the drum surface and prevents good transfer to copy paper.

To solve these problems, in order to improve the heat dissipation of the drum, proposals have already been made to integrally form protrusions that act as heat dissipation fins on the inner surface of the cylinder (for example, Japanese Patent Application Laid-Open Nos. 54-103358, Utsukai Showa 56-12056
However, there is a limit to the number of integrally molded fins that can be increased, and it has not been possible to achieve the desired cooling effect on the photosensitive drum.

(Purpose of the invention) The purpose of the invention is to solve the problems mentioned above. That is, firstly, the heat dissipation of the photosensitive drum is significantly increased, and even when a heating fixing roll is brought into contact with a part of the circumferential surface, the rotation leads to a charging section that forms an electrostatic latent image. Second, when blowing air from one end of the drum to promote cooling, one end of the length of the drum and one end of the drum must be Thirdly, to make the surface temperature as uniform as possible over the entire length without creating a temperature gradient between the parts and the surface, and thirdly, to make the material as simple as possible to manufacture. Furthermore, fourthly, the support structure for the drum shaft can be simplified, making it easy to attach and detach the drum, and the center of the drum can be precisely aligned with the center of the drum shaft. The purpose is to ensure that there is no risk of deviation or error.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a tubular inner cylinder serving as a bearing inside an outer cylinder serving as a drum body or cylinder as a support for a photosensitive layer. By integrally molding a plurality of radial connecting rims, the drum shaft can be inserted into the inner cylinder to easily and accurately support the rotation of the drum, and the drum can be easily attached and detached. I will do it with Uruchino. In addition, by inserting and installing corrugated fins along the axial direction between the above-mentioned inner and outer cylinders, a sufficient heat dissipation promoting effect can be obtained when used in combination with means for promoting forced air cooling using a fan from one end of the drum. . Furthermore, by using a plurality of types of corrugated fins with mutually different wave numbers or crest numbers, the fin pitch can be gradually made denser from one end of the cooling air inlet side of the drum to the other end. , the temperature gradient of the surface temperature in the length direction of the drum is reduced.

That is, in this invention, the inner cylinder for a bearing and the outer cylinder forming the drum body are integrally molded concentrically via a plurality of radial connection rims, and each adjacent radial connection rim is formed between the inner and outer cylinders. At the position between the rims, multiple types of corrugated fins, which are full-gate fins corrugated in the cross-sectional direction and have different wave numbers, have both top end surfaces in the height direction aligned with the outer circumferential surfaces of the inner and outer cylinders. By sequentially inserting the drum in the axial direction so that it is in contact with the inner circumferential surface, and by integrally joining and fixing the abutting portions, the cooling air inflow side of the drum is gradually inserted in stages from one end to the other end on the cooling air inlet side. The object of the present invention is to provide a photosensitive drum for an electronic copying machine, characterized in that the fin pitch is densely arranged.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

In Figures 1 and 2, (1) is an outer cylinder as a drum cylinder on which a photosensitive layer is formed, and (2) is an inner cylinder for a bearing provided concentrically inside this. . These two cylinders (1)<2) are integrally connected to each other by a plurality of radial connecting rims (3). Such a molded body consisting of an inner and outer double cylinder can be easily manufactured by extrusion molding of an aluminum alloy, for example. In particular, it is advantageous for the outer cylinder (1) to have a wall thickness of about 2 to 4 am in terms of strength, weight, heat dissipation, etc. In addition, in the illustrated embodiment, six radial connecting rims (3) are provided at equal intervals, but any number of radial connecting rims (3) may be provided as long as it is two or more, and generally up to about eight radial connecting rims (3) are shown. Set arbitrarily within the range.

Between the above-mentioned inner and outer cylinders (2) and (1), corrugated fins (4) are inserted from one end in the axial direction at positions between the adjacent radial connecting rims (3) and (3) and are fixedly connected. . The corrugated fins (4) are corrugated in the cross-sectional direction with a corrugation height corresponding to the distance between the inner and outer cylinders (2) and (1), that is, the height of the connecting rim (3), Therefore, in the above insertion and installation state, both top end surfaces (4a) are in contact with the outer surface of the inner tube (2) and the inner surface of the outer tube (1), respectively. This abutting part is integrally joined to both the inner and outer cylinders (2>(1). This joining is achieved by using an aluminum brazing sheet for the corrugated fin (4). The simplest and most common method is to melt a brazing filler metal (brazing filler metal) and braze both side edges to the outer cylinder (1) and the inner cylinder (2).

In this embodiment, the corrugated fins are also joined and fixed using this method.

By the way, the corrugated fins (4) include a plurality of types having different wave numbers or ridge numbers. That is, in the illustrated embodiment, there are first to third fins (4A), (4B), and (4C) each having a length that is approximately equal to three parts of the entire length of the b drum, and the first fin (4A) has the same number of fins as the number of fins. has a narrow width of only one, the second fin (4B) has two ridges, and the third fin (4C) has three ridges. .

These first to third fins connect to each connecting rim (three
), , (3) are sequentially inserted and installed from one end of the outer cylinder (1) along the axial direction, respectively. Therefore, as shown in FIG. 1, the corrugated fins (4
) The pitches are arranged to become progressively denser in stages. That is, as shown in FIGS. 2 to 4, in a length range of approximately 1/3 of the total length of the drum on the one end side, as shown in FIG. 4, the first fin (4A) exists, and the fin pitch is sparse with two radial heat sinks (4b) formed between the inner and outer cylinders (1) and (2), and in the length range of about 1/3 of the middle part. , as shown in Fig. 3, there is a second fin (4B) and four radial heat sink parts
4b), and approximately 1/3 of the other end side.
When the length reaches a certain length range, as shown in FIG. 2, a third fin (4C) is present, and the fin pitch is dense, forming six radial heat sink portions (4b).

In particular, the third fin (4C) is made of corrugated fin (4) as a material before insertion as shown in FIG.
Its width (W) is narrowed on the inner cylinder (2) side and expanded on the outer cylinder (1) side, so that the cross section is deformed into a substantially fan-like shape between the inner and outer cylinders (2) and (1). It is said that it was inserted and installed in.

The arrangement of fins with different wave numbers as described above is not limited to the embodiment. Therefore, for example, only two types of fins with different wave numbers may be used;
Sometimes more than one type is used. - In some cases, no radiation fins are provided at one end on the cooling air inflow side. These matters are determined appropriately from a design standpoint in relation to the usage conditions of the drum.

Although the corrugated fin (/I) in the illustrated embodiment is shown as having a flat heat dissipation portion (4b), for the purpose of further improving heat dissipation efficiency, the heat dissipation plate portion (4b) is shown as having a flat plate shape.
In addition to b), it is also recommended to use a material with corrugations in the cross-sectional direction or length direction, or a material with a large number of cut and raised portions formed in a looper shape.

(Effects of the Invention) Since the photosensitive drum according to the present invention has the above-described configuration, as is clear from consideration of the examples, the inner cylinder (2) has a drum shaft (the illustrated path). This can be easily pivoted into a copying machine by inserting it. Therefore, unlike conventional products, it is possible to provide rotational support without requiring additional accessories such as a flange body or bearing, and the structure can be significantly simplified. In addition, since the inner and outer cylinders are integrally molded, the center of the outer cylinder (1) is automatically and precisely aligned with the drum shaft that passes through the inner cylinder (2), so that the center of the outer cylinder (1) can be accurately aligned with the drum shaft that passes through the inner cylinder (2). When it comes into contact with the corona discharger group, developing device, or transfer paper guide, etc.
Problems such as damage to these or the photosensitive layer on the drum surface can be prevented.

Moreover, in addition to the thin heat dissipation plate part (4b) of the corrugated fin (4) existing inside the outer cylinder (1) in contact with this, the radial connecting rim (3) connected to the inner cylinder (2) is present. ) also has excellent heat dissipation properties, and even if the outer cylinder is heated due to discharge from a corona discharger or even irradiation with light from a lamp, heat is quickly dissipated and overheating occurs. The rotation speed of the drum can be increased to increase the speed. In particular, as shown in FIG. 1, by blowing air from one end of the drum with a fan (7) to perform forced air cooling, heat dissipation can be easily promoted. Even in the case where the transferred image is fixed on the transfer paper by the heating fixing port on the surface, the temperature of the heated outer peripheral surface of the drum must be sufficiently high before the heated outer peripheral surface of the drum reaches the charging section. This makes it possible to lower the temperature to a low temperature, which is extremely effective in further downsizing copying machines.

Furthermore, corrugated fins are particularly used as heat dissipation fins, and their top end surfaces are brought into contact with the inner and outer cylindrical surfaces, so that the contact area between them can be increased, and the heat dissipation efficiency can be greatly increased. The installation work of inserting the fins between the two cylinders (2) (1) is as simple as inserting the corrugated fins individually between the connecting rims (3) (3), and multiple heat dissipation plates located radially can be installed. It is advantageous in terms of manufacturing because it can be provided at one time, and the number of heat sink parts, that is, the fin pitch, can be arbitrarily changed by selecting the number of corrugations of the corrugated fins used.

In the cooling promotion effect by the fan (7), in the drum according to the present invention, by including a plurality of types of corrugated fins with different wave numbers for heat radiation,
Since the fin pitch is configured to gradually become denser from one end of the cooling air inlet side of the drum to the other end, the heat dissipation efficiency is approximately equalized over the entire length of the drum shaft. − can be converted into Therefore, there is no large humidity gradient in the surface humidity between one end and the other end of the drum, and a uniform action can always be maintained over the entire length of the drum.

As described above, the present invention has an extremely simple structure, enables accurate setting and placement of the rotation center of the photosensitive drum, avoids troubles caused by eccentric rotation, etc., and also makes it possible to attach and detach the photosensitive drum. In addition, it is possible to install a large number of heat dissipation fins, which would be impossible if they were integrally molded into the outer cylinder, which would not be possible at the side bottom.
Due to its extremely excellent heat dissipation performance,
There is no risk of troubles due to overheating even when used continuously for long periods of time, and the surface temperature can be controlled to be approximately even over the entire length, maintaining good functionality.In addition to reducing the size of the photosensitive drum itself, By heating and fixing the toner on the transfer paper around the drum, it is possible to simplify the fixing mechanism. It has a great effect.

[Brief explanation of the drawing]

The drawings are partially cutaway perspective views showing embodiments of the present invention;
Figures 4 through 4 are the lines ``G'' and ``G'' in Figure 1 and fV -
Each sectional view of the TV wire and FIG. 5 are perspective views showing the state before the corrugated fin (third fin) is inserted and installed. (1)... Outer cylinder, (2)... Inner cylinder, (3)... Connecting O rim, (4)... Corrugated fin, <4A).
...First fin, (4B)...Second fin, (4C)
...Third fin, (7)...Cooling fan. The above procedures (method) September 1985)] 22nd, Director General of the License Agency, Mr. Uga Michibe tll
, Indication of the case 1982 Patent Application No. 64654M 2, Name of the invention Photosensitive drum for electronic copying machine 3, Person making the amendment Relationship to the case Patent applicant Address 6-224 Kaiyama-cho, Sakai City Name Representative of Showa Aluminum Co., Ltd. stone
Chika I 4, Agent Address: Shinsaibashi Iwasaki Building, 72-4 Unagidani Nakanocho, Minami-ku, Osaka Name (7116) Patent Attorney Hisashi Shimizu (06) 245-2718 The first drawing on page 16, line 4 of the specification is ``Figure 1'' is corrected. that's all

Claims (2)

[Claims] (1) The inner cylinder for the bearing and the outer cylinder forming the drum body are integrally molded concentrically via a plurality of radial connecting rims, and between the above-mentioned inner and outer cylinders, and between the adjacent radial connecting rims. At this position, a plurality of types of corrugated fins having different wave numbers in the cross-sectional direction are arranged such that both top end surfaces in the height direction are aligned with the outer circumferential surface and inner circumferential surface of the inner and outer cylinders. By sequentially inserting the fins in the axial direction so that they are in contact with the fins, and by integrally joining and fixing the abutting portions, the fin pitch is gradually adjusted in stages from one end of the drum on the cooling air inlet side to the other end. A photosensitive drum for an electronic copying machine, characterized in that the drum is densely structured. (2) A photosensitive drum for an electronic copying machine according to claim 1, wherein an aluminum brazing sheet is used for the corrugated fins, and the fins are brazed to both the inner and outer cylinders using the skin material.