Electrophotography – Control of electrophotography process – Of plural processes
Reexamination Certificate
2001-04-26
2003-01-07
Ngo, Hoang (Department: 2852)
Electrophotography
Control of electrophotography process
Of plural processes
C399S027000
Reexamination Certificate
active
06505011
ABSTRACT:
BACKGROUND AND SUMMARY
Cross reference is made to the following applications filed concurrently herewith: entitled “Edge Enhancement Scavenging Device” and “Dynamic Duty Cycle For Increased Latitude”.
This invention relates generally to a hybrid jumping developer system, and more particularly concerns a method for employing an underdeveloped solid control patch in a printer control system.
In a typical electrophotographic printing process, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive is member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet. After each transfer process, the toner remaining on the photoconductor is cleaned by a cleaning device.
In a machine of the foregoing type, utilizing a hybrid jumping development (HJD) system, the development roll, better known as the donor roll, is powered by two development fields (potentials across an air gap). The first field is the ac jumping field which is used for toner cloud generation and has a typical potential of 2.25 k volts peak to peak at 3.25 kHz frequency. The second field is the dc development field which is used to control the amount of developed toner mass on the photoreceptor.
SUMMARY OF THE INVENTION
There is provided an electrophotographic printing machine having a latent image is recorded on a photoconductive member with the latent image being developed with marking particles, including: means for recording a test patch consisting of a solid patch; means for developing the test patch with marking particles wherein said developed patch has a solid portion and an edge portion; means for measuring a density of the solid portion of said test patch; means for measuring a density of the edge portion of said test patch; means for generating a first output signal corresponding to the density of the solid portion of said test patch; and means for generating a second output signal corresponding to the density of the edge portion of said test patch.
REFERENCES:
patent: 5887221 (1999-03-01), Grace
Featherly Peter J.
Leclerc Gerald Scott
Bean II Lloyd F.
Ngo Hoang
Xerox Corporation
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