Bi-directional Scanning Alignment Calibration for Electrophotographic Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bi-directional scanning in electrophotographic devices increases complexity due to the need for two reference points and amplifies print image imperfections, requiring effective calibration techniques for manufacturing, servicing, and end-user operations while maintaining inexpensiveness, stability, and low complexity.
Innovation Solution
A calibration method using diagnostic patterns with intentional and unintentional pixel mismatches to form a calibration page, where the darkest bar indicates optimal alignment, allowing for visual or automated selection to correct misalignments and improve print quality by forming multiple bars symmetrically about a central best calibration bar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bi-directional scanning is implemented to increase device efficiency, then productivity is improved, but device complexity increases due to the need for two reference points and additional calibration requirements
Solution Approach 1:
The calibration process is segmented into distinct patterns (first pattern with no pixel mismatch, second pattern with intentional pixel mismatch) that can be independently analyzed. This allows the complex calibration problem to be broken down into manageable components that can be processed separately and then combined to achieve overall alignment correction.
Solution Approach 2:
The invention changes the parameter of pixel alignment by intentionally creating patterns with known pixel mismatches. By varying the pixel displacement parameters in the test patterns and observing the resulting printed bar darkness, the system can determine the optimal alignment parameters that minimize deviations and achieve best print quality.
2Ease of manufacture
If bi-directional scanning is used to reduce manufacturing cost through smaller components, then manufacturing cost is reduced, but measurement precision deteriorates due to amplified print image imperfections
Solution Approach 1:
The invention performs preliminary calibration actions by printing test patterns with known intentional pixel mismatches before actual printing operations. This preliminary measurement allows the system to characterize its alignment deviations and establish correction factors in advance, ensuring high measurement precision is maintained despite the use of cost-effective bi-directional scanning components.
Solution Approach 2:
The system implements feedback by measuring the darkness of printed bars from the test patterns and using this information to determine the actual alignment state. This feedback loop allows the system to detect and correct alignment deviations, maintaining measurement precision even with the simplified bi-directional scanning architecture.
3Ease of operation
If calibration patterns with intentional pixel mismatch are used to facilitate alignment detection, then ease of operation is improved, but device complexity increases due to additional calibration procedures
Solution Approach 1:
The invention uses visual darkness variations (analogous to color/intensity changes) in the printed calibration bars to indicate alignment quality. The darkest bar corresponds to the optimal alignment, providing an intuitive visual feedback mechanism that simplifies the calibration operation. Users can easily identify the best alignment by simply observing which bar appears darkest, without requiring complex measurements or interpretations.
Data Source
AI summary
Methods and apparatus include aligning printing of a bi-directionally scanning electrophotographic (EP) device, such as a laser printer or copy machine. At least first and second scan lines formed in opposite directions define a calibration page for manufacturing, servicing or end-user operating. The page includes pluralities of diagnostic patterns repeatedly tiled together in various formats. In one instance, a first pattern defines a substantially rectangular cell of pixels (pels) for at least a first and second scan line of opposite directions. A second pattern defines the first pattern except at least one of the pels of either the first and second scan lines is intentionally displaced at least one pel width in the scan direction. Upon repeatedly tiling groups of either the first or second patterns together, multiple bars of the calibration page are formed. A darkest of the bars represents a preferred calibration setting of the EP device.