Photodiode Array Detector with Variable Charge Accumulation Time
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Solution Overview
Problem
In spectrophotometers, the precision of detection signals is compromised when sample components are at high concentrations, leading to noise interference and inaccurate concentration determination due to low light intensity in certain wavelength ranges.
Innovation Solution
A photodiode array detector with a light receiving element array where multiple elements detect the same wavelength range as a unit, with varying charge accumulation times set based on light source intensity across the unit, allowing for high-precision signal detection even with low light quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the charge accumulation time is set with reference to the wavelength at which the light intensity reaches its maximum, then the detection signal in the high light intensity region is strong, but the detection signal in the low light intensity region becomes weak and is buried in noise
Solution Approach 1:
The patent applies local quality by setting different charge accumulation times for different wavelength regions. Specifically, the light receiving element array is divided into multiple regions (first, second, and third regions) corresponding to different wavelength ranges, and each region is assigned an appropriate charge accumulation time based on its local light intensity characteristics. This allows each region to optimize its signal-to-noise ratio according to its specific conditions, rather than using a single uniform accumulation time for all wavelengths.
2Measurement precision
If the charge accumulation time is extended to improve signal strength in low light intensity regions, then the S/N ratio improves, but the accumulated charge becomes saturated in high light intensity regions
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially differentiated charge accumulation times. The light receiving element array is divided into multiple regions with different accumulation time settings: shorter accumulation times for high light intensity regions to prevent saturation, and longer accumulation times for low light intensity regions to enhance signal strength. This localized parameter optimization allows the system to simultaneously avoid saturation in bright regions while maintaining high S/N ratios in dim regions.
3Ease of operation
If a single charge accumulation time is used for all light receiving elements, then the device operation is simple, but the detection precision varies significantly across different wavelength regions
Solution Approach 1:
The patent implements local quality by dividing the light receiving element array into multiple regions (first, second, and third regions) with different charge accumulation time settings. Each region is optimized for its specific wavelength range and light intensity characteristics, allowing precise detection across the entire spectral range while maintaining manageable system complexity through automated region-based control.
4Device complexity
If the charge accumulation time is set based on the maximum light intensity wavelength, then the device complexity remains low, but the detection precision in low light intensity wavelength regions deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality through automated region-based charge accumulation time setting. The light receiving element array is divided into multiple regions with different accumulation time settings optimized for their respective wavelength ranges. The control unit automatically manages these different settings, so while the detection precision is significantly improved across all regions, the operational complexity remains low due to automated control.
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 configuration enhances the precision of detection signals by utilizing longer charge accumulation times for subsequent light receiving elements, effectively reducing noise influence and improving concentration determination accuracy across a broader range of light intensities.
Implementation Method 1
Light which has entered each light receiving element is converted to an electric charge and accumulated
Data Source
AI summary
A photodiode array detector used for detecting light which has undergone wavelength separation by a spectroscopic element, the photodiode array detector including: a light receiving element array wherein, taking a plurality of light receiving elements which detect light of the same wavelength range as one unit, a plurality of such units are arrayed in the direction of dispersion of said wavelength; and a charge accumulation time setting unit which sets different charge accumulation times for the plurality of light receiving elements within the one unit.