Optical Sensor Calibration for Printing Apparatus Platen Gap
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Solution Overview
Problem
Existing printing apparatuses face errors in color calibration due to variations in patch density readings caused by differences in the distance between the optical sensor and the medium surface, leading to inconsistent ink dispensing across the medium.
Innovation Solution
A printing apparatus and method that uses a patch pattern with varying gradation levels, where patches are positioned at different distances from the optical sensor, and blank regions are used to measure medium density, allowing for accurate prediction and correction of ink dispensing based on reflected light signals, thereby minimizing positional errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If patches are printed at different positions on the medium, then the optical sensor can detect positional variations in platen gaps, but the reading accuracy of patch density varies due to distance differences from the sensor
Solution Approach 1:
The patent changes the parameter of patch positioning by printing patches at multiple different positions across the medium surface. This allows the system to detect and compensate for platen gap variations at different locations, transforming a source of error into a means for calibration and correction of ink dispensing consistency.
2Measurement precision
If the optical sensor reads patches at varying distances from the medium surface, then positional errors are introduced, but maintaining a fixed reading distance reduces the ability to detect and correct for platen gap variations
Solution Approach 1:
The patent performs preliminary measurement of platen gap variations by reading patches at multiple positions before the actual printing process. This advance detection allows the system to establish correction data that compensates for positional errors, ensuring accurate density measurement and consistent ink dispensing throughout the printing operation.
3Reliability
If multiple patches of different gradation levels are printed for calibration, then color calibration can be performed, but the complexity of the calibration process increases
Solution Approach 1:
The patent segments the calibration process into distinct components: printing multiple patches with different gradation levels at various positions, reading each patch individually, and processing the data systematically. This segmentation transforms a complex monolithic calibration process into manageable discrete steps, making it easier to implement and verify while maintaining high color calibration accuracy.
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
This approach ensures accurate color calibration by accounting for positional variations in platen gaps and medium cockling, resulting in consistent image density across the medium, reducing ink consumption and maintaining calibration accuracy.
Implementation Method 1
an optical sensor that emits light on the medium while moving in the second direction and outputs a signal based on intensity of reflected light
Data Source
AI summary
An optical sensor that outputs a signal based on reflected light intensity is moved in a second direction orthogonal to a transport direction of a medium. A pattern containing patches representing a plurality of gradation levels between a first gradation level and a second gradation level denser than the first is formed such that each patch is located at a different position in the second direction. Signals of the patch of the second gradation level and another patch are outputted. Then signals are outputted with respect to positions in the second direction in a blank region onto which ink has not been dispensed, one of the positions being located at the same position as the patch of the second gradation level, the other position being located at the another patch, so as to correct a dispensing amount corresponding to the gradation level of the another patch.