Time-of-flight circuit compensates transducer capacitance drift

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Solution Overview

Problem

Ultrasonic flow meters face challenges in accuracy due to temperature variations affecting transducer capacitance and impedance, leading to fluctuations in flow rate measurements.

Innovation Solution

A time-of-flight (TOF) generating circuit and method that calculates the difference in flight times between transducers in a pipeline filled with fluid, using a transmitter, receiver, signal generating circuit, correlation circuit, measuring circuit, and transformation circuit to account for phase differences and ambient temperature changes, thereby improving measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional ultrasonic flow measurement is used, then the flow meter has low installation cost and low pressure loss, but the measurement accuracy deteriorates due to temperature variations affecting transducer capacitance and impedance

Engineering Contradiction:

Improveflow rate measurement accuracyVSAvoidtemperature variation effect

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by measuring the capacitance of the transducer, which changes with temperature, and using this capacitance value to compensate for measurement errors. The system dynamically adjusts the measurement based on the detected capacitance parameter to maintain accuracy across varying temperatures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by using the measured capacitance value to generate a compensation signal that is fed back to correct the flow rate measurement. The capacitance measurement provides feedback about temperature effects, which is then used to adjust the final measurement result

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If transducer capacitance and impedance are affected by temperature, then the system responds to ambient changes, but measurement accuracy deteriorates due to fluctuations in flow rate readings

Engineering Contradiction:

Improveresponse to ambient temperature changesVSAvoidflow rate measurement stability

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of temperature-induced capacitance changes into a beneficial measurement tool. By measuring the capacitance change caused by temperature, the system obtains information about the temperature effect and uses this information to compensate for measurement errors, turning a source of error into a correction mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If phase difference measurement is performed between transducers, then flight time difference can be calculated, but measurement complexity increases due to need for correlation operations and signal processing

Engineering Contradiction:

Improveflight time measurement accuracyVSAvoidsignal processing circuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary approach by using correlation operations to compare the phase of signals from different transducers. The correlation circuit acts as an intermediary that processes the phase information and extracts the flight time difference without requiring complex direct measurement circuits

Inventive Principle:

Principle #24Intermediary (Mediator)

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 TOF generating circuit provides more accurate flow speed and flow rate measurements by compensating for temperature-induced variations, enhancing the reliability of ultrasonic flow meters.

Implementation Method 1

a transmitter, coupled to the first transducer; a receiver, coupled to the second transducer

Methodology Applied

Scientific EffectUltrasonic wave transmission: Ultrasound

Implementation Method 2

a correlation circuit, configured to at least receive the input signal to perform a correlation operation to generate a correlation signal

Methodology Applied

Scientific EffectCorrelation operation:

Implementation Method 3

a transformation circuit, configured to selectively transform the measurement signal or the first measurement signal from a frequency domain to a time domain to generate a TOF difference signal

Methodology Applied

Scientific EffectFrequency domain to time domain transformation:

Data Source

PatentUS11486749B2Time-of-flight generating circuit and chip, flow meter and method of the same

Publication Date: 2022.11.01 SHENZHEN GOODIX TECH CO LTD

AI summary

The application discloses a time-of-flight generating circuit, coupled to a first transducer and a second transducer, wherein there is a distance greater than zero between the first transducer and the second transducer, and a fluid having a flow speed flows sequentially through the first transducer and the second transducer, wherein the time-of-flight generating circuit includes: a transmitter, coupled to the first transducer; a receiver, coupled to the second transducer; a signal processing circuit, coupled to the transmitter and the receiver; and a correlation circuit, a measuring circuit and a transformation circuit, coupled to the signal processing circuit. The application also discloses a chip, flow meter, and method of the same.