Electrophotography – Image formation – Development
Reexamination Certificate
2000-08-15
2001-11-13
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Development
C399S090000, C399S119000, C439S843000
Reexamination Certificate
active
06317575
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to providing a firm interlock between a journal end, such as of a core or hub or shaft, and the bore on an element to be fixed to the journal end in a manner which prevents relative rotation therebetween. Known systems include the use of one or more mating flats ribs or other features on the outer surface of the journal end and on the inner surface of the bore, which prevent relative rotation and provide positive alignment. However such known systems are unsatisfactory for use in some precision apparatus systems which require a firm interlock between a journal end such as a shaft having a flat and an element having a bore having a flat which mates with the flat on the shaft, where any degree of “sloppiness” or relative movement is detrimental to the operation of the apparatus, resulting in extensive failures.
Reference is made to our U.S. Pat. No. 5,822,654, the entire disclosure of which is hereby incorporated herein by reference thereto. U.S. Pat. No. 5,822,654 discloses an electrostatographic reproduction machine which incorporates a customer-replaceable developer unit (CRU) or developer cartridge. Said unit has a fixed housing, an opposed pair of bearing support elements and a developer roll sleeve which is supported by the bearing support elements for rotation about a non-rotating central core member containing magnetic poles which are angularly positioned to provide an optimum magnetic field array for the proper development of toner images formed on the developer roll. The bearing support elements each have an end sleeve portion having an outer surface provided with a flat for mating with a flat in a receiving bore on the housing, and also having an inner bore surface having a flat for mating with a flat on the journal end of the central magnet core of the developer roll. The bearing support elements rotatably support the developer roll sleeve while the central core is fixed to the bearing support elements which are fixed to the housing. An electrical bias must be applied to the outer surface of the rotating developer sleeve to provide for proper development and control of the charged surface, and therefore the bearing support elements are electrically conductive and in contact with a power source through their connection with the housing/with near zero capacitance.
The central core of the fixed magnetic developer roll contains a plurality of spaced and aligned magnets having developer transport poles and trim poles which are angularly positioned to impart optimum magnetic field properties to the rotating developer roll sleeve, spaced therefrom for the proper development of the marking particles formed on the developer sleeve for transfer to the charged areas of the photoreceptor roll. Any relative movement between the fixed location or position of the magnet-containing core and the housing of the developer cartridge will change the location of the magnetic field imparted or induced to the surface of the developer sleeve and will result in improper development of the marking particles, which contain magnetic carrier particles and fusible toner particles, and external damage to the apparatus. It has been found that the use of mating flats on the central core shaft and the inner bore of the bearing support member, and mating flats on the outer hub of the bearing support member and on the supporting bore of the housing do not provide complete resistance to relative movement of either the central core or the bearing support element, i.e., they provide “sloppy” connections which reduce the quality of the electrostatic copies by producing prints which are light and non-uniform.
Firm motion-resistant connections between shafts and hub bores having rotation-resisting mating flats is also desirable in numerous devices, particularly scientific measurement or indexing devices, where even the slightest degree of “sloppiness” resulting in the slightest degree of “give” or relative movement can be detrimental to the accurate operation of the device. It is known to provide a hub with a radial locking screw, through its flat, which engages the mating flat on the shaft in order to tighten the connection therebetween but this is not always completely effective, nor is it possible with all assemblies such as that of U.S. Pat. No. 5,822,654.
SUMMARY OF THE INVENTION
The present invention relates to providing a firm, motion-resistant interlock between a mating journal end or shaft and a bore, each having one or more flats which mate with a corresponding number of flats on the other to prevent relative rotation therebetween. The invention is characterized by forming on the inner surface of the bore or on the outer surface of the journal end or shaft a plurality of axial “crush ribs” or thin, spaced elevations of relatively soft metal or plastic composition, which ribs are crushable or spreadable over their supporting surface under the pressure applied when the shaft is forced into the bore. The soft metal or plastic which is displaced from the crushed ribs spreads in all directions to fill any airspace between the shaft and the bore as the shaft is seated within the bore, to form a firm interlock which resists any degree of relative rotation or “sloppiness” between the parts, while any excess displaced material is ejected.
REFERENCES:
patent: 5583473 (1996-12-01), Yamashita
patent: 5768658 (1998-06-01), Watanabe et al.
patent: 5822654 (1998-10-01), Damji et al.
Damji Dhirendra C.
Kumar Ajay
Chen Sophia S.
Perman & Green LLP
Xerox Corporation
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