Toner Image Transfer Surface Color Density Control
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Solution Overview
Problem
Image printing systems face challenges in maintaining consistent print quality over time due to ink/toner variations, temperature fluctuations, and environmental factors, leading to unpredictable color representation.
Innovation Solution
A computer-implemented method and system that measures toner images on an image transfer surface and printed images on output media, adjusts contone values to match target tone reproduction curves, and updates image transfer surface reflectance data to achieve precise color density and tone reproduction, using sensors and processors to control subsequent toner image data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color characterization methods are used with a large set of color samples and mathematical fitting, then accurate printer characterization transform can be achieved, but the process becomes complex and time-consuming with multiple patches needing to be printed and measured
Solution Approach 1:
The patent extracts the essential characterization information by using only a small set of gray patches (e.g., 5 patches at 0%, 20%, 40%, 60%, 80% area coverage) instead of a large set of color samples. This extraction approach captures the tone reproduction curve (TRC) characteristics sufficient for accurate color characterization while dramatically simplifying the measurement process and reducing the number of patches that need to be printed and measured.
Solution Approach 2:
The system performs preliminary TRC measurements and characterizations during manufacturing or initial setup, storing these characterization data for later use. This preliminary action allows the printer to operate with pre-established color profiles without requiring complex real-time measurements, thereby reducing operational complexity while maintaining characterization accuracy.
2Manufacturing precision
If full-width patches are measured by full-width array sensor during cycle up to obtain printer model of TRC at each pixel column, then spatial uniformity across the printer page can be corrected, but the measurement time and processing complexity increase
Solution Approach 1:
The patent segments the full-width patch measurement into multiple smaller measurement zones or uses a reduced set of measurement positions across the printer page. Instead of measuring every pixel column, the system strategically selects representative positions that capture the spatial variation in TRC. This segmentation approach maintains spatial uniformity correction capability while significantly reducing measurement time and data processing requirements.
Solution Approach 2:
The system applies partial measurement action by measuring only the essential portions of the printer page that are representative of overall spatial uniformity. Rather than performing exhaustive full-width measurements at all positions, the patent uses a reduced set of measurements that provide sufficient information for effective spatial correction, thereby reducing measurement time while maintaining correction quality.
3Reliability
If control patches for each developer housing are created in inter-document zone between successive images, then toner response curve can be maintained, but the available space for control patches is limited and measurement accuracy may be compromised
Solution Approach 1:
The patent merges the control patch measurement function with the regular image printing process. Control patches are integrated into the image data stream and printed alongside or within the image areas, allowing the same imaging and measurement systems to serve dual purposes. This merging approach maintains reliable toner response curve measurements while utilizing the full capabilities of the printing and measurement systems, overcoming the limitations of separate dedicated control patch areas.
4Measurement precision
If reference location color is controlled through Vmag, laser power, and Vmc actuators with TRC halftone dot linearization, then absolute color calibration is achieved, but the system complexity and number of actuators to control increase
Solution Approach 1:
The patent achieves absolute color calibration by measuring and characterizing the actual TRC output of the printer and using this empirical data to create accurate color profiles. Instead of relying on complex theoretical models and multiple actuators (Vmag, laser power, Vmc), the system directly measures the printer's actual performance and compensates through software-based color transformation. This parameter change approach shifts from controlling multiple physical actuators to measuring and compensating through software, reducing system complexity while maintaining calibration accuracy.
Data Source
AI summary
A method for controlling a tone reproduction curve of an image printing system includes generating an actual printed image tone reproduction curve using printed image data from a printed image sensor; determining a set of adjusted contone values by comparing the actual printed image tone reproduction curve with a target printed image tone reproduction curve, where the adjusted contone values being representative of the print contone values at which target color density data of the printed image is achieved in the image printing system; and determining adjusted image transfer surface reflectance data to update a target image transfer surface tone reproduction curve, where the adjusted image transfer surface reflectance data being obtained by interpolating the target image transfer surface tone reproduction curve at the adjusted contone values; and controlling subsequent toner image data to achieve the updated target image transfer surface tone reproduction curve.