Light Source Array Adjustment for Print Uniformity
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Solution Overview
Problem
Manufacturing inconsistencies in liquid electrophotography printing systems, particularly in the writing head and light-emitting elements, lead to non-uniformities in printed images due to misalignment and optical variations, resulting in print defects like banding.
Innovation Solution
A mechanism is implemented to analyze printed images for non-uniformities and adjust the light sources accordingly, using a pattern with greyscale patches and position indicators to identify and correct focal plane curvature, thereby improving print quality and production yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light sources are used to selectively discharge portions of a photoconductive surface, then printing functionality is achieved, but manufacturing inconsistencies cause non-uniformity in printed images
Solution Approach 1:
The system performs preliminary analysis of the printed image to identify non-uniformity regions before final printing. By detecting and mapping light source variations in advance using test patterns, the system creates a correction profile that compensates for manufacturing inconsistencies, ensuring uniform output without requiring ultra-precise manufacturing tolerances
Solution Approach 2:
The system dynamically adjusts light source parameters (intensity, exposure time) based on detected non-uniformity. By varying the operational parameters of individual light sources according to their performance characteristics, the system compensates for manufacturing variations and achieves uniform image density across the printed surface
2Ease of manufacture
If manufacturing inconsistencies are present in writing head components, then production cost is reduced, but print quality deteriorates with banding defects
Solution Approach 1:
The system implements a closed-loop feedback mechanism where printed images are analyzed to detect banding and non-uniformity. This feedback information is used to identify problematic light sources and adjust their parameters or replace them, continuously improving print quality while maintaining production efficiency. The feedback loop enables the system to adapt to manufacturing variations without compromising reliability
Solution Approach 2:
The system performs preliminary testing and analysis before full production printing. By using test patterns and analyzing the optical properties of light sources in advance, the system identifies and corrects potential quality issues before they affect production output, ensuring consistent print quality while maintaining efficient manufacturing
3Device complexity
If light source uniformity is not adjusted, then device complexity is minimized, but regions of non-uniformity appear in printed images
Solution Approach 1:
The system performs self-diagnosis and self-correction by analyzing its own output. The image analysis capability allows the printing system to automatically detect non-uniformity regions and identify the corresponding light sources, then adjust parameters or trigger replacements without external intervention, maintaining image uniformity while avoiding complex external calibration equipment
Solution Approach 2:
The system adjusts light source operational parameters based on detected performance variations. By dynamically changing intensity or exposure parameters for individual light sources, the system compensates for uniformity issues without requiring complex mechanical adjustments or additional hardware components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces print defects by adjusting the light sources to achieve uniformity, enhancing the quality and consistency of printed images through on-press analysis and correction.
Implementation Method 1
light-emitting elements on a 'writing head' may be used to selectively discharge portions of a photoconductive surface
Implementation Method 2
selectively discharge portions of a photoconductive surface that are to receive print agent
Data Source
AI summary
A light source adjustment apparatus is disclosed. The light source adjustment apparatus includes processing apparatus to receive a scanned image of a pattern printed by a print apparatus onto a printable medium, the pattern including a plurality of blocks of print agent of a first colour printed during a printing operation in which light sources of a light source array irradiate a photoconductive surface; analyse the scanned image to identify a region of non-uniformity within the plurality of blocks of print agent; correlate a location of the identified region of non-uniformity with a corresponding light source in the light source array; determine, based on the identified region of non-uniformity, an adjustment to be made to a parameter of the corresponding light source; and generate a signal to effect the determined parameter adjustment with regard to the corresponding light source. A method and a print apparatus are also disclosed.