Electrophotography – Image formation – Transfer
Reexamination Certificate
1999-11-24
2001-03-20
Beatty, Robert (Department: 2852)
Electrophotography
Image formation
Transfer
C310S312000
Reexamination Certificate
active
06205315
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to methods and systems for tuning a transducer, and to transducers produced by such methods and systems.
2. Description of Related Art
In a typical electrophotographic printing process, a photoconductive member is initially charged to a substantially uniform potential and the charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposing the charged photoconductive member selectively dissipates the charge on the photoconductive member in the irradiated areas. Thus, an electrostatic latent image can be recorded on the photoconductive member corresponding to informational areas contained within the original document used to expose the photoconductive member. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact with the photoconductive member. Generally, the developer material is made from toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a developed image on the photoconductive member. The developed image is then transferred from the photoconductive member to a copy substrate, such as a sheet of paper.
Thereafter, heat or some other treatment is applied to the developed image to permanently affix the toner particles to the copy substrate. In a final step, the photoreceptive member is cleaned to remove any residual developing material on the photoconductive surface in preparation for successive imaging cycles.
The electrophotographic printing process described above is well known and is commonly used for light lens copying of an original document. Analogous processes also exist in other electrostatographic printing applications such as, for example, digital printing where the latent image is produced by a modulated laser beam, or ionographic printing and reproduction, where charge is deposited on a charge retentive surface in response to electronically generated or stored images.
Typically, the process of transferring charged toner particles from an image bearing support surface, such as a photoreceptor, to a second support surface, such as a copy sheet or an intermediate transfer belt, is enabled by overcoming adhesion forces holding the toner particles to the image bearing surface. In a conventional electrostatographic printing machine, toner images are transferred between support surfaces by electrostatic induction using a corona generating device. In this process, the second support surface is placed in direct contact with the developed toner image on the image bearing surface, while the back of the second support surface is sprayed with a corona discharge. The corona discharge generates ions having a polarity opposite that of the toner particles. This electrostatically attracts and transfers the toner particles from the image bearing surface to the second support surface.
A critical aspect of the transfer process focuses on applying and maintaining high intensity electrostatic fields and/or other forces in the transfer region to overcome the adhesive forces acting on the toner particles. These electrostatic fields and other forces need to be carefully controlled to induce the charged toner particles to physically detach and transfer to the second support surface without scattering or smearing of the developer material.
To enhance electrostatic toner release from an image bearing surface, recent systems have incorporated a transducer arranged along the back side of the image bearing surface. This transducer can generate focused vibratory energy that can be applied uniformly to the back side of the image bearing member. In such systems, toner transfer is enhanced due to the toner particles mechanically releasing from the image bearing surface. As a result, the toner particles will effectively transfer to the second support surface despite the electrostatic charges in the transfer zone being insufficient by themselves to attract the toner particles from the image bearing surface to the second support surface.
Exemplary systems of this nature are disclosed in U.S. Pat. No. 4,987,456 to Snelling et al.; U.S. Pat. No. 5,005,054 to Stokes et al.; U.S. Pat. No. 5,010,369 to Nowak et al.; U.S. Pat. No. 5,016,055 to Pietrowski et al.; U.S. Pat. No. 5,081,500 to Snelling et al.; and U.S. Pat. No. 5,210,577 to Nowak, each incorporated herein by reference in its entirety. As disclosed in U.S. Pat. No. 4,987,456, a transducer, or “resonator”, that is able to generate focused vibratory energy generally includes a transducer element coupled to a resonating waveguide member. The waveguide member has a contacting tip that is brought into tension or penetration contact with the image bearing belt to couple the vibratory motion to the image bearing belt. In some systems which incorporate a transducer that applies uniform vibratory energy to the photoreceptor, widthwise slots are provided along the length of the transducer waveguide to segment the transducer into individually vibrating portions. This provides an increased velocity response across the waveguide, as well as improves the uniformity of the velocity. Such segmentation is disclosed in the incorporated references discussed above, among others. In these references, the waveguide portion is cut perpendicularly to the plane of the image bearing surface, and generally parallel to the direction of travel of the image bearing surface. This creates an open-ended slot between each segment, such that each segment acts more or less individually in response to the transducer.
SUMMARY OF THE INVENTION
However, there is a tendency for the response of the segmented waveguide segments to be elevated at one edge and/or to fall off along the opposite edge of the transducer as a result of the continuous mechanical behavior of the resonator device. The edges of the transducer correspond to marginal regions of the photoconductive member. These phenomena are commonly collectively called the “edge effect”. However, uniform response along the entire device, arranged across the entire width of the imaging surface of the photoconductive member, is desirable.
This invention provides systems and methods for tuning a transducer so that it has an acceptably uniform response. If transducers can be thus tuned, substantial cost savings can be realized because virtually every transducer that is manufactured can be adjusted to operate within specified performance standards, resulting in very good yield.
Accordingly, in some exemplary embodiments, this invention provides a transducer that includes a vibratory energy producing element that generates vibratory energy, and a waveguide member coupled to the vibratory energy producing element. The waveguide member transmits the vibratory energy. The waveguide member has a longitudinal axis and is divided along the longitudinal axis into a plurality of waveguide segments. The waveguide segments may each have a same general size and shape. The transducer is tuned by altering a mass of at least one of the waveguide segments relative to a mass of the other waveguide elements. The altered mass may be either an increase in the mass or a decrease in the mass.
In other exemplary embodiments, this invention provides methods and/or systems for tuning a transducer. In the methods and systems of this invention, a velocity profile of the activated transducer is created, and at least one waveguide segment causing unacceptable velocity uniformity deviation is detected based on the velocity profile. In response, a mass of the at least one waveguide segment is altered as discussed above.
Methods and/or systems for tuning a transducer according to this invention may further include monitoring an impedance or an admittance of the activated transducer, detecting a bimodal response based on the monitored impedance or admittance, successively applying force to the individual waveguide segments until the bimodal
Falvo John R.
Montfort David B.
Beatty Robert
Oliff & Berridg,e PLC
Xerox Corporation
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