Band-Limiting Filter for Endoscope Color Tone Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Synchronous type endoscope apparatuses experience variations in image quality due to differences in spectral sensitivity characteristics of CCDs, leading to inconsistent color tone reproduction across different devices, even when white balance processing is performed.
Innovation Solution
An endoscope apparatus that generates band-limited normal illumination light within a predetermined bandwidth for RGB lights, using a band-limiting filter to stabilize the spectral sensitivity characteristics and ensure consistent image quality across different CCDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If white balance processing is performed to correct color tone, then color accuracy is improved, but variations in spectral sensitivity characteristics of different CCDs still cause inconsistent image quality
Solution Approach 1:
The patent changes the spectral parameter of the illumination light by introducing a band-limiting filter that restricts the illumination light to a specific wavelength range (e.g., 400-700nm for visible light). This parameter change ensures that all CCDs receive light within a controlled spectral band, reducing the impact of their individual spectral sensitivity variations and achieving consistent image quality across different devices.
2Loss of information
If broad-spectrum white light is used for illumination, then color information completeness is improved, but spectral sensitivity variations among CCDs cause color tone inconsistencies
Solution Approach 1:
The patent modifies the spectral parameter of the illumination light by using a band-limiting filter to restrict it to a specific wavelength range. This creates a controlled spectral environment where the illumination light's characteristics are standardized, allowing different CCDs to capture consistent color information within that band despite their individual sensitivity variations.
3Device complexity
If no spectral limitation is applied to illumination light, then device complexity is reduced, but image quality varies due to CCD spectral sensitivity differences
Solution Approach 1:
The patent introduces a band-limiting filter as an intermediary component in the illumination path. This filter acts as a mediator that standardizes the spectral characteristics of the illumination light before it reaches the CCD, thereby reducing the impact of CCD spectral sensitivity variations without requiring complex post-processing or calibration systems.
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 stabilizes the intensity balance of RGB signals, maintaining consistent image quality and color tone reproduction by limiting the illumination light within a common spectral band, thereby reducing the impact of CCD spectral sensitivity variations.
Implementation Method 1
a band-limited normal illumination light generation section for generating a discrete band-limited normal illumination light by limiting light in visible light range of RGB to within a bandwidth with a predetermined light amount
Data Source
AI summary
A band-limiting filter of the invention exhibits a trimodal filter characteristic, and includes, for example, band-limiting transmittance filter characteristic portions Rb, Gb, and Bb for wavelength regions of red, green, and blue, respectively. More specifically, the band-limiting transmittance filter characteristic portions Rb, Gb, and Bb, for example, have bandpass characteristics in which the respective center wavelengths are 630 nm (full width at half maximum λ1=30 to 90 nm), 540 nm (full width at half maximum λ2=20 to 60 nm), and 440 nm (full width at half maximum λ3=50 to 80 nm). This makes it possible to obtain an image of a predetermined color tone by restraining an influence of spectral sensitivity characteristic of an image pickup device when the band-limiting filter is applied to a synchronous type endoscope for performing color image pickup to perform observation under normal illumination light.