CIS Scanner Nozzle Shading Correction via Dynamic Exposure
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in achieving precise nozzle shading due to the limited dynamic range of Contact Image Sensors (CIS) scanners, which hinder the detection and correction of nozzle discharge variations, leading to density variations in prints.
Innovation Solution
A nozzle shading method that employs a CIS scanner with multiple read conditions, including varying light exposure and scanner speed, to read charts for shading correction, convert luminance values to density values, and create correction tables for precise shading correction, enabling high-precision nozzle shading despite the scanner's narrow dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a CCD scanner is used for reading prints, then measurement precision and dynamic range are improved, but device cost and complexity increase
Solution Approach 1:
The density measurement process is segmented into multiple reading operations with different exposure conditions. Instead of relying on a single high-precision CCD scanner reading, the system divides the measurement into multiple CIS scanner readings taken under varying light exposure conditions (different LED intensities or exposure times), allowing accurate density measurement across different ranges through segmented data collection and processing
Solution Approach 2:
The system changes the exposure parameters of the CIS scanner dynamically during the reading process. By adjusting the light emission intensity or exposure time of the LED light source, the system adapts the reading conditions to match the density range being measured, enabling accurate measurement of both light and dark areas with a single scanner hardware configuration
2Device complexity
If a CIS scanner is used instead of a CCD scanner, then device cost and complexity are reduced, but measurement precision and dynamic range deteriorate
Solution Approach 1:
The CIS scanner system employs dynamic exposure adjustment where the light emission conditions are changed during the reading process. The system dynamically adapts the exposure parameters based on the density range being measured, transforming a static, limited-range scanner into a dynamic system capable of accurate measurements across a wide density range through parameter variation
Solution Approach 2:
The system performs multiple partial readings under different exposure conditions rather than attempting a single comprehensive reading. By taking multiple measurements with different exposure levels and combining them through the correction tables, the system achieves complete density range coverage that exceeds the capabilities of any single reading condition
3Measurement precision
If multiple read conditions are used with a CIS scanner, then measurement precision is improved, but reading time and processing complexity increase
Solution Approach 1:
The system performs preliminary actions by pre-establishing correction tables that map the relationships between different exposure conditions and actual density values. These correction tables are created in advance through calibration processes, allowing the system to quickly apply corrections during actual measurements without performing complex real-time calculations, thus reducing processing time while maintaining precision
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 method allows for accurate nozzle shading correction using a CIS scanner, ensuring uniform ink discharge from nozzles, reducing costs and space requirements compared to CCD scanners, and improving print quality by maintaining precision and uniformity.
Implementation Method 1
a reading step for reading charts for shading correction with a CIS (Contact Image Sensor) type scanner with a plurality of read conditions, while emitting light from light emitters
Data Source
AI summary
An inkjet printing apparatus includes a plurality of nozzles for discharging ink, a CIS (Contact Image Sensor) type scanner for reading, as image data, charts for correction printed in the ink discharged from the nozzles, light emitters for emitting light to the charts for correction, a scanner controller for causing the scanner to scan the charts for correction with a plurality of read conditions, a correction table creator for creating nozzle shading correction tables based on the image data read, and a shading corrector for carrying out shading correction for the nozzles based on the correction tables.