Correlator Using Geometric Sampling for Particle Size Analysis
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Solution Overview
Problem
Existing particle size analysis methods using photon correlation spectroscopy face challenges in achieving accurate measurements over a wide range of particle sizes due to trade-offs between channel number and sampling time, leading to reduced accuracy and increased bias noise.
Innovation Solution
A correlator that sets delay times or sampling times for each channel based on a geometric sequence, allowing for integral handling of linear, exponential, and multi-tau sampling methods, with a control part determining sampling times as Tn = fn × To, where fn is a recurrence formula, enabling improved accuracy and synchronization with pulse signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linear sampling method is used with equal time intervals, then circuit configuration is simple, but large number of channels are required for wide range of particle sizes
Solution Approach 1:
The patent applies dynamics by making the sampling time variable across different channels rather than fixed. Each channel n has a sampling time Tn that dynamically adjusts based on a geometric progression ratio, allowing the system to adapt to different particle size ranges while maintaining a manageable number of channels. This resolves the contradiction by introducing temporal variability to replace the need for numerous fixed-time channels.
Solution Approach 2:
The patent changes the sampling time parameter across channels according to a geometric progression formula Tn = T0 × r^(n-1). This parameter change allows the system to cover a wide range of particle sizes with fewer channels, as each channel is optimized for specific time scales. The geometric progression efficiently spans multiple orders of magnitude in particle size detection.
2Adaptability or versatility
If exponential sampling method is used with different sampling times for each channel, then wide range of particle sizes can be covered, but sampling time increase leads to shortage of data points on small particles
Solution Approach 1:
The patent uses geometric progression to systematically vary sampling times across channels, where Tn = T0 × r^(n-1). This controlled parameter change ensures that early channels (for small particles) have short sampling times to capture sufficient data points, while later channels (for large particles) have longer sampling times. The geometric ratio r is optimized to balance the distribution of data points across all particle sizes.
Solution Approach 2:
The patent implements periodic sampling actions at different time intervals for different channels. Each channel performs periodic counting at its specific sampling time Tn, creating a structured sequence of measurements that efficiently covers multiple particle size ranges. This periodic action with varying periods resolves the data point shortage for small particles while maintaining coverage for large particles.
3Measurement precision
If multi-tau method is used with blocks of channels, then shortcomings of linear and exponential methods are overcome, but base line fluctuation increases for channels with longer intervals
Solution Approach 1:
The patent applies geometric progression to sampling times, which provides a more uniform distribution of measurement points compared to the block-based multi-tau method. By using Tn = T0 × r^(n-1) with an optimized ratio r, the patent reduces the excessive time intervals between measurements that cause baseline fluctuation, while still covering the required particle size range efficiently. This continuous geometric progression avoids the discrete block structure that generates harmful baseline noise.
Data Source
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AI summary
In order to improve an accuracy of an autocorrelation function, a correlator comprises a counter 61 for receiving a pulse signal at given time intervals (sampling times) and counting the number of pulses; a shift register 63 for receiving the number of pulses counted by the counter 61 and performing sequential time delay; an operation part 64 for performing a product-sum operation of an output from the counter 61 and that delayed by the shift register 63 for each channel; and a control part 65 for setting a delay time or a sampling time by the shift register 63 on a basis of a relationship of the Fibonacci sequence.