US 7,398,025 B2 · White vector feedback adjustment

Abstract

Control circuitry associated with an electrophotographic imaging device is adapted to operate in conjunction with a sensor to adjust a difference in electrical bias between a photoconductive surface and an associated roller. The sensor detects a reflectance or luminosity of a developed image and the control circuitry uses this detected information and information related to reflectance or luminosity of the underlying surface and the developing toner to determine whether the developed image is produced as desired. The control circuitry adjusts the difference in electrical bias between the photoconductive surface and an associated roller in response to a comparison between the detected and desired images. In one embodiment, a predetermined test pattern is developed over a range of electrical bias differences and an optimum operating point is determined from the iterations.

Claims23

Dependent claims

An electrophotographic image forming device comprising:

a photoconductive unit;
a charger unit operative to charge a surface of the photoconductive unit to a first voltage;
an imaging unit forming a latent image on the surface of the photoconductive unit by selectively discharging the surface of the photoconductive unit to at least a second voltage by illumination thereof;
a developer roller having a surface biased to a third voltage and operative to develop toner to the latent image on the surface of the photoconductive unit;
a substrate onto which the developed image is transferred from the surface of the photoconductive unit;
a sensing unit operative to detect a reflectance of the developed image on the substrate and a reflectance of a non-developed area on the substrate;
and
a controller operative to produce subsequent images while adjusting the third voltage until a desired reflectance of one of the subsequent images on the substrate is obtained, and then adjust the first voltage to produce a desired reflectance of the non-developed area on the substrate while maintaining the third voltage at the value resulting in the desired reflectance of the one subsequent image.

5 more elements

In an electrophotographic imaging device, a method of adjusting a difference in electrical potential between a charged, unexposed photoconductor surface and a developer roll, the method comprising:

repeatedly creating latent images of a predetermined test pattern on said charged, unexposed photoconductor surface by selectively illuminating portions of said photoconductor surface with an optical device;
creating developed test patterns by supplying toner from said developer roll to the photoconductor surface to develop the latent image patterns;
transferring the developed test patterns to a substrate;
measuring a reflectance of each developed test pattern on the substrate and adjusting the developer roll potential after each measurement until a desired reflectance of one of the developed test patterns is obtained;
and
adjusting the electrical potential of the charged, unexposed photoconductor surface while maintaining the developer roll potential at the value resulting in the desired reflectance of the one developed test pattern in response to the measured reflectance of the developed test pattern.

3 more elements

Dependencies are inferred from the claim text.

White vector feedback adjustment

Life of this patent

White vector feedback adjustment

Life of this patent

Abstract

Claims23