Particle Counter False Count Subtraction
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Solution Overview
Problem
Existing particle counters suffer from false counts due to noise from laser beam sources, photoelectric converters, and other factors, which are difficult to treat effectively.
Innovation Solution
A particle counter with a memory section to store the frequency of false counts and a subtraction section that adjusts measurements based on this frequency, either by using pre-calculated occurrence frequencies or a relational expression between direct current levels and false counts, to subtract false count values from discrete values during measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser diode with high-frequency component is used to reduce laser noise, then false counts from laser beam source are reduced, but false counts from other factors (photoelectric converter noise, circuit voltage variation, cosmic rays) remain untreated
Solution Approach 1:
The invention converts the harmful effect of false counts into a beneficial correction process. By detecting and counting false count occurrences during a measurement period, the system calculates an average false count value and subtracts it from the total particle count, thereby transforming the noise problem into a quantifiable and correctable parameter that improves overall measurement accuracy
Solution Approach 2:
The system implements a feedback mechanism where the measured false count frequency is fed back into the calculation process. The subtraction section uses the calculated average false count value to adjust the final particle concentration result, creating a closed-loop correction system that continuously compensates for noise effects based on actual observed false count rates
2Measurement precision
If complex noise reduction methods are used to treat all noise factors, then comprehensive false count reduction is achieved, but device complexity increases
Solution Approach 1:
The system performs self-correction by automatically detecting its own false count rate during operation. The measurement section and subtraction section work together to autonomously identify noise patterns and apply corrections without requiring external calibration or complex preprocessing, allowing the system to self-adjust to different operating conditions and noise levels
Solution Approach 2:
The invention changes the approach from attempting to physically eliminate various noise sources to instead changing the parameter being measured and corrected - specifically, measuring the false count frequency as a separate parameter and using it to adjust the final particle concentration calculation. This parameter-based correction approach is simpler than physical noise elimination methods
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 allows for precise control of false counts, resulting in more accurate particle concentration measurements by accounting for the occurrence frequency and changing use conditions.
Implementation Method 1
a particle detecting section for detecting particles in a sample
Implementation Method 2
noise generated by a photoelectric converter
Data Source
AI summary
A particle counter for measuring the number of floating particles contained in a sample to determine the particle concentration therein includes: a memory section for storing a relational expression between the direct current level output from a photoelectric converter when no particles exist and the frequency of occurrence of false counts; and a subtraction section for determining the frequency of occurrence of the false counts corresponding to the direct current level output from the photoelectric converter at the time of commencement of measurement with reference to the relational expression stored in the memory section and subtracting a value based on the frequency of occurrence of the false counts from a discrete value after commencement of measurement.