Streak Compensation via Model-Based Projections in Digital Printers
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Solution Overview
Problem
Conventional printing technologies face challenges in effectively controlling streaks, which are one-dimensional defects affecting image quality, due to non-ideal responses of xerographic components and raster output scanning device variations, leading to unsatisfactory image non-uniformities.
Innovation Solution
A method utilizing a full width sensing device and Spatially Varying Tone Reproduction Curves (STRCs) to measure and correct streaks by constructing a Printer Streaks Basis Function Model, updating reflectance profiles, and calculating control signals to compensate for streaks across all area coverage levels, thereby improving transient response and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If streak compensation is performed using conventional methods, then image non-uniformities are corrected, but the transient response is slow and cannot keep up with rapidly changing streak states
Solution Approach 1:
The patent performs preliminary action by measuring streak profiles at multiple area coverage levels during printer setup and using these measurements to construct a basis function model. This model is then used to predict streak behavior at all area coverage levels during runtime without requiring repeated measurements, enabling fast transient response while maintaining compensation accuracy.
Solution Approach 2:
The patent creates a simplified mathematical representation (basis function model) that copies the essential characteristics of streak behavior across different area coverage levels. By measuring streaks at a limited number of levels and using the basis function model to project these characteristics to all levels, the system achieves fast response without losing accuracy.
2Measurement precision
If streak profiles are measured at all area coverage levels, then complete streak behavior is captured, but measurement time and computational complexity increase significantly
Solution Approach 1:
The patent segments the measurement process by measuring streak profiles at only a limited number of area coverage levels rather than all levels. The measured data at these discrete levels is then used with the basis function model to infer streak behavior across the complete range of area coverage levels, significantly reducing measurement time while maintaining precision.
Solution Approach 2:
The patent changes the approach from directly measuring all parameters (streak profiles at all area coverage levels) to measuring a subset of parameters and using a mathematical model to derive the remaining parameters. The basis function model transforms the limited measurement data into complete streak behavior predictions across all area coverage levels.
Data Source
AI summary
Streak compensation in a digital printer is provided utilizing a spatially varying Printer Model and Run Time updates to generate Spatially Varying Tone Reproduction Curves (STRCs) which are used as actuators to compensate for streaks during run time. A full width array sensor is used to measure streak profiles and the STRCs are used as actuators to compensate for streaks. Streak profile measurements taken at a limited number of area coverage levels combined with a Printer Streaks Basis Function Model are used to estimate and project the streak behavior at all area coverage levels and at all inboard-to-outboard spatial locations. The projection is then used in a pixel-wise error feedback control scheme to drive each profile to a desired shape, thereby compensating for streaks.