Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
1999-09-11
2001-06-12
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Photoconductive member
C399S116000, C399S117000
Reexamination Certificate
active
06246851
ABSTRACT:
FIELD OF THE INVENTION
The invention at hand concerns a photo conductor drum comprised of a drum body with an outer cylindrical surface, a flange attached to the drum body at the front side with a snug fit and a centric axis of rotation for the drum body, which coaxially feeds through the drum body and flange and can be connected with the flange.
BACKGROUND OF THE INVENTION
A photo conductor drum of the above mentioned kind is known, for example, from the EP 0 629 927 A2. In this known photo conductor drum the flange is oversized in regard to the inner diameter of the drum body and the connection of flange and drum body is achieved by the shrinking of the flange in low temperature and ensuing insertion in the drum body. It is generally known that these photo conductor drums require an extreme centric running precision of the cylindrical surface of the photo conductor drum. Therefore, an adjustment is carried out on the photo conductor drum referred to in the above-mentioned paper. In this procedure, a collar sitting on the axle which is the axis of rotation of the drum body, is inserted in the flange. However, there is free space between the inside of the flange and the collar so that an adjustment with setting screws (which have a radial effect), can be made afterwards to achieve the necessary centric running precision. This kind of adjustment is time consuming and also inaccurate. The radial end position of the setting screws can not be adjusted with the necessary accuracy of measurement because most of the time the setting screws are made of a harder material than the collar. Inaccuracies will already occur in the process of screwing it on. In addition to that, deformation and abrasion of the setting screws will lead to inaccuracies in the course of time.
The task of the invention at hand is therefore, to create a photo conductor drum of the above mentioned kind which already demonstrates the necessary centric running precision after the production and assembling of the particular modules to a photo conductor drum without extensive adjustments.
SUMMARY OF THE INVENTION
The solution to this task delivers an invention based photo conductor drum of the above-mentioned kind with the characteristic features of the main claim. According to the invention, an axle part is intended which is connected to the flange without radial free space. This axle part replaces the collar that has been used until now which had free space to the inside of the flange. The previously required setting screws are no longer necessary.
A variation of the invention is, for example, a solution where the axle part is cast into the centric area in the flange. But according to another alternative solution, the axle part as well can be fastened tightly in a centric area of the flange and could be connected to it with screws or a similar device.
A preferred advancement of the invention intends that the axle part shows a part of a ring which is located on the inside of the flange and is connected to it with screws or a similar device. Furthermore it is preferably intended, that the axle part outside the flange has an area with a smaller diameter which serves as a mount for a ball bearing.
Within the connecting area between the drum body and flange it could be advantageous if the drum body is coated with an anodic material of, for example, several mm to make the assembling easier. This results in a greater ability to glide. At the same time a low transitional resistance will be maintained.
Generally, the invention based photo conductor drum shows two opposite flanges that are connected by a centric axle and this axle centrally feeds through the axle part. There are various possibilities to fasten the two opposite flanges of the drum body against each other in an axial direction. One variation of the invention calls for the use of pull anchors.
Preferably, the flanges, within the scope of its invention, consist of aluminum and the axle parts are made of steel.
Another preferred advancement of the invention shows that the snug fit between flange and drum body in axial direction extends only over a part of the strength of the flange material. This has the advantage, that the drum body and the flange can be handled easier during the treatment prior to their assembling. If it comes to minor damages of the drum body or the flange, they can not be permitted to occur in the area of the snug fit, or this would result in inaccuracies in the snug fit which could have an effect on the centric running precision of the drum body. Damages on the other hand, which occur outside of the intended snug fit, are harmless. In this variation of the invention it is therefore possible, to take hold of the drum body or flange outside of the snug fit with gripping devices without impairment of the snug fit. An advancement in this scope of the invention shows that the outside area of the flange has a radial overhanging collar which has a larger diameter than the flange in the area of the snug fit and the drum body in its axial outer area shows a thread on the inside, through which an outer ring bar of the drum body is formed which overlaps the collar of the flange and aligns with it on the outside. It is also preferred, that the thread of the drum body is measured in a way that a free space remains between the ring bar of the drum body and the collar of the flange. That way there is no snug fit in this area. The snug fit is preferably located in axial direction further inside.
Furthermore the fitting process between flange and drum body can preferably be eased by applying a cone or a bevel on the inside of the flange and/or applying a cone or a bevel on the outside of the snug fit on the cylindrical inside of the drum body which is facing the flange.
A preferred advancement of the invention is that the drum body, from the view of the snug fit on the inside, shows an auxiliary thread or a ring groove. This auxiliary thread or ring groove can be used for an axial connection between the drum body and the flange, by using a cramp or similar device for example, which will be taken in this auxiliary thread or ring groove and by than connecting this cramp with the flange using a screw connection or similar device which will fix the flange axially. Naturally there are other mounting variations for which auxiliary thread could be of use as well.
Another preferred advancement of the invention also shows that the drum body and/or the flange and/or the ball bearing fit is rotated in a clamping device during the production of the photo conductor drum. This provides a high accuracy in measurement and makes an accurate coordination of the parts relative to each other possible and is therefore of advantage also in connection with the other mentioned characteristics for the achievement of the high centric running precision in regard to the outer cylindrical diameter area of the photo conductor drum.
Following is a more detailed description of the invention at hand using preferred embodiments with reference to the attached drawings.
REFERENCES:
patent: 3985432 (1976-10-01), Hou et al.
patent: 5130751 (1992-07-01), Sato et al.
patent: 5570160 (1996-10-01), Miwa et al.
patent: 5952141 (1999-09-01), Ohno et al.
Tietze Wolfgang
Weber Heinrich
Angenehm Law Firm
Chen Sophia S.
Friederichs N Paul
Ngu Hoang
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