Image Reader Shading Correction for Continuous Print Inspection
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Solution Overview
Problem
The efficiency of LED light sources in image reading devices changes over time due to temperature fluctuations, causing variations in light intensity that affect the accuracy of image inspection and colorimetry, necessitating downtime for shading correction, which is inefficient.
Innovation Solution
An image reading device with a hardware processor performs shading correction before printing, using a white reference plate to adjust for light source variations, and extracts image data from unprinted regions to create sheet color data, ensuring accurate inspection and colorimetry without downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the image reading device operates continuously for extended periods, then productivity is improved, but light source efficiency changes due to temperature fluctuations causing measurement precision degradation
Solution Approach 1:
The system performs preliminary shading correction by reading a white reference plate at the start of operation and before printing begins. This preliminary action captures the initial light source characteristics and creates baseline sheet color data, allowing the system to compensate for subsequent light drift without interruption.
Solution Approach 2:
The system continuously monitors reading results and compares them against reference values obtained from the white reference plate. When light source efficiency changes are detected, the system automatically adjusts shading correction parameters and updates sheet color data, creating a closed-loop feedback mechanism that maintains measurement precision throughout continuous operation.
2Measurement precision
If shading correction is performed during continuous printing, then measurement precision is maintained, but productivity decreases due to downtime
Solution Approach 1:
The system performs all necessary shading correction measurements and sheet color data creation before printing begins. By completing the white reference plate reading and initial shading correction in advance, the system eliminates the need to interrupt printing for calibration purposes.
Solution Approach 2:
The system maintains continuous printing operation by pre-completing all calibration and correction actions before printing starts. The useful action of shading correction is performed once at the beginning, allowing printing to proceed continuously without interruption for subsequent corrections.
3Measurement precision
If sufficient lighting time is ensured before printing, then measurement precision is improved, but productivity decreases due to downtime
Solution Approach 1:
The system performs the white reference plate reading and initial shading correction as a preliminary action immediately before printing begins. This eliminates the need for extended pre-heating or warm-up periods, allowing the system to reach stable measurement conditions right at the start of printing.
Solution Approach 2:
The system dynamically adjusts the timing and parameters of shading correction based on actual operating conditions. By performing correction at the moment of need rather than requiring prolonged advance preparation, the system optimizes both measurement precision and productivity.
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 maintains consistent reading results by adjusting for light source fluctuations, improving inspection and colorimetry accuracy without stopping the printing process.
Implementation Method 1
causing the image reader to read a white reference plate disposed opposite the image reader
Implementation Method 2
an LED light source has replaced a halogen light source in an image reading section
Data Source
AI summary
An image reading device includes: an image reader that is disposed downstream of an image forming apparatus and reads a printed material that is a sheet on which an image has been formed by the image forming apparatus; and a hardware processor that controls the reading by the image reader. The hardware processor: performs shading correction on the image reader when the image reading device is activated or before printing is started by the image forming apparatus, based on shading data acquired by causing the image reader to read a white reference plate disposed opposite the image reader; extracts image data of an unprinted region of the printed material during the reading by the image reader, based on scan data of the printed material read by the image reader; and creates sheet color data for the image reader based on the image data that has been extracted.