Near-Infrared Tablet Inspection Calibration for Pixel Sensitivity Noise
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Solution Overview
Problem
The sensitivity variation among wavelength components and light-receiving elements in imaging elements used for spectral analysis in PTP sheet inspection devices leads to significant noise levels and reduced inspection accuracy, particularly in high-speed manufacturing environments like PTP packaging machines.
Innovation Solution
An inspection device and calibration method that corrects sensitivity variations by calculating correction values based on both wavelength and luminance characteristics of the imaging elements, ensuring uniform light intensity across the imaging area, thereby enhancing inspection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectral analysis is used for inspection of objects in PTP sheets, then inspection capability for different type objects is improved, but sensitivity variation among wavelength components and light-receiving elements causes noise and reduces inspection accuracy
Solution Approach 1:
The patent applies parameter changes by calculating correction values that account for sensitivity variations across different wavelength components and light-receiving elements. The system measures actual sensitivity parameters for each element and uses these to normalize the spectral data, transforming the raw measurements into corrected values that compensate for element-specific variations and reduce noise in the inspection process
Solution Approach 2:
The patent implements feedback by measuring the actual sensitivity characteristics of each light-receiving element and wavelength component, then using these measurements to generate correction values that are applied back to the spectral analysis process. This closed-loop approach continuously refines the inspection accuracy by incorporating real sensitivity data into the correction algorithm
2Productivity
If imaging elements with multiple light receiving elements are used to inspect multiple pocket portions simultaneously, then productivity is improved, but sensitivity variation among individual light receiving elements increases noise
Solution Approach 1:
The patent applies local quality by assigning individual correction values to each light-receiving element based on its specific sensitivity characteristics. Rather than using a uniform correction approach, the system tailors the correction to each element's local properties, ensuring that elements with higher sensitivity variations receive appropriate compensation specific to their performance characteristics
Solution Approach 2:
The patent changes the sensitivity parameters of individual light-receiving elements by measuring each element's response and calculating element-specific correction values. These correction values are then applied to normalize the output from multiple elements, allowing simultaneous inspection of multiple pocket portions while maintaining consistent accuracy across all detection points
3Ease of manufacture
If correction values are calculated based on uniform light intensity assumption, then calibration process is simplified, but actual non-uniform light intensity across imaging area causes remaining noise
Solution Approach 1:
The patent applies self-service by having the system automatically measure its own light intensity distribution across the imaging area and use these self-measured values to generate correction factors. The inspection device performs self-calibration by detecting the actual light conditions during operation and adjusting its correction values accordingly, eliminating the need for external calibration equipment or complex manual procedures
Solution Approach 2:
The patent performs preliminary action by measuring and storing the light intensity distribution characteristics before actual inspection begins. The system pre-calculates correction values based on the measured non-uniform light intensity pattern, so that when inspection occurs, the corrections are already in place to compensate for the known light distribution variations
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 method improves inspection accuracy by minimizing noise levels and ensuring consistent sensitivity across the imaging area, suitable for high-speed PTP packaging machines.
Implementation Method 1
The imaging element such as the CCD area sensor is comprised of a plurality of light receiving elements arranged in a matrix arrangement
Implementation Method 2
Light passing through a slit 86 out of the parallel light L 3 forms slit light L 4 in a strip form and enters a spectroscope (prism) 87 serving as a spectroscopic unit. The slit light L 4 entering the spectroscope 87 is dispersed into lights of respective wavelength components
Implementation Method 3
The slit light L 4 entering the spectroscope 87 is dispersed into lights of respective wavelength components, which are projected as an optical spectrum (optical spectral image) L 5 onto a light receiving surface 89 of an imaging element 88
Data Source
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AI summary
There are provided an inspection device configured to improve the inspection accuracy in an inspection that is performed by taking advantage of spectral analysis, as well as a PTP packaging machine and a calibration method of the inspection device. An inspection device 22 comprises an illumination device 52 configured to irradiate tablets 5 with near-infrared light; and an imaging device 53 configured to disperse reflected light of the near-infrared light that is reflected from the tablets 5 and take an image of the reflected light. The inspection device 22 is configured to perform an analysis process, based on spectroscopic image data obtained by the imaging device 53. The inspection device 22 performs a predetermined arithmetic operation of standard spectroscopic image data obtained in advance by taking an image of an optical spectrum with regard to a predetermined standard plate, so as to determine a characteristic of each pixel row and thereby grasp a wavelength sensitivity characteristic of an imaging element. The inspection device 22 subsequently calculates a correction value with regard to each pixel of standard spectroscopic image data. In the process of an inspection, the inspection device 22 corrects a luminance value of each pixel of inspection spectroscopic image data obtained by taking an image of an inspection object, based on the correction value with regard to the pixel.