Closed loop controls for transfer control in first transfer for optimized image content
AssigneeXerox Corporation
InventorsJoanne Lai Zen Lee, John T. Buzzelli
Life of this patent
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Abstract
An electrostatic transfer control method that avoids undesired retransfer effects. A printing device develops and transfers several control patches. The patches are transferred at different electrostatic set points and a control strategy is utilized involving one or more density sensors to measure the transferred toner patches whereby the obtained density information can be used to compute the optimal value of electrostatic transfer bias. Print operators can adjust the bias value based on preferences for predetermined standards.
Claims15
A method of operating a document processing system having a plurality of marking devices of different colors individually operable to transfer marking material in a first transfer operation onto an intermediate transfer structure, the method comprising:
- a) importing a plurality of control patches of preselected colors wherein the colors are repetitively imported in control patches at a plurality of electrostatic transfer bias set points;
- b) sensing a density of the control patches with a sensor;
- c) detecting a highest density color of the repetitively imported patches;
- and
- d) determining an optimal first transfer bias based on the detected highest density, whereby subsequent operation of the document printing system selectively employs the optimal first transfer bias;
- wherein the determining comprises computing the optimal first transfer bias (OFTB) by a function:
- Optimal First Transfer Bias=(0.5*(R+G)−0.5*(M+Y))*X+0.5*(M+Y)
- where R=transfer bias when red patch's density is the highest
- G=transfer bias when green patch's density is the highest
- M=transfer bias when magenta patch's density is the hiqhest
- Y=transfer bias when yellow patch's density is the highest
- and X=weight from 0 to 1, where 0 means single separation is more desired and 1 means blended color is more desired.
A method of controlling print transfer using transfer biases and bias set points comprising the steps of:
- a) selecting first color transfer biases;
- b) selecting first color transfer biases set points;
- c) printing test patches using transfer biases and set points varied from the first color transfer biases and the first color transfer biases set points;
- d) determining a highest density color patch from the test patches;
- e) computing an optimal first transfer bias;
- f) printing and evaluating a sample patch;
- g) repeating the process beginning with step b) selecting other transfer bias set points, until an operator signals an approval;
- and
- h) employing the approved settings to print a job;
- where the optimal first transfer bias is calculated using an algorithm which comprises:
- Optimal First Transfer Bias=(0.5*(R+G)−0.5*(M+Y))*X+0.5*(M+Y)
- where R=transfer bias when red patch's density is the highest
- G=transfer bias when green patch's density is the highest
- M=transfer bias when magenta patch's density is the highest
- Y=transfer bias when yellow patch's density is the highest
- and X=weight from 0 to 1, where 0 means single separation is more desired and 1 means blended color is more desired.
A system for controlling print transfer comprising:
- a printer comprised of a plurality of one color print modules, each module comprising a print head and an adjoining nip, each module associated with one individual color;
- at least one sensor associated with each individual color;
- a processor to process an algorithm to calculate the optimal transfer bias based on data gathered by the sensors;
- a graphical user interface to facilitate user data entry and approval acknowledgment data;
- and wherein the processor further receives the data gathered by the sensor, receives user entered settings data and executes the algorithm using the received data;
- and the printer prints at least one test patch printed out in response to a calculated optimal transfer bias;
- where the algorithm comprises:
- Optimal First Transfer Bias=(0.5*(R+G)−0.5*(M+Y))*X+0.5*(M+Y)
- where R=transfer bias when red patch's density is the highest
- G=transfer bias when green patch's density is the highest
- M=transfer bias when magenta patch's density is the highest
- Y=transfer bias when yellow patch's density is the highest
- and X=weight from 0 to 1, where 0 means single separation is more desired and 1 means blended color is more desired.
Dependencies are inferred from the claim text.