Viscoelasticity measurement method and viscoelasticity measurement device
Inventors
Odagiri, Tsutomu • Nakamoto, Taku • Miura, Shinsuke
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Publication Number
US-12098989-B2
Publication Date
2024-09-24
Expiration Date
Abstract
Provided is a viscoelasticity measuring method and a viscoelasticity measuring device which reduce the number of measurement points and simplify a device design. In order to achieve the object described above, in a viscoelasticity measuring method, a vibrator is immersed in a measurement liquid, a drive signal for driving the vibrator at a resonance frequency (f00) of the vibrator in the air is output, vibration of the vibrator is detected by a detection sensor, and a signal phase delay (Δ) of a sensor output signal of the detection sensor with respect to the drive signal is measured.
Core Innovation
A viscoelasticity measuring method immerses a vibrator in a measurement liquid, outputs a drive signal for driving the vibrator at a resonance frequency (f00) of the vibrator in the air, detects vibration of the vibrator by a detection sensor, and measures a signal phase delay (Δ) of a sensor output signal with respect to the drive signal. The method measures the signal phase delay (Δ) and uses it to determine a viscoelastic phase angle (δ) of the measurement liquid. The method relates the viscoelastic phase angle (δ) to the signal phase delay (Δ) using numerical expressions dependent on the detection sensor type.
The method calculates an absolute value (ηab) of a complex viscosity of the measurement liquid from an amplitude (x00) at the resonance frequency (f00) in air and uses the measurement liquid density and resonance quantities together with numerical expressions. Based on the signal phase delay (Δ), the method calculates the viscoelastic phase angle (δ). Using ηab and δ, the method calculates a complex viscosity coefficient (η*) and a complex rigidity modulus (G*).
A viscoelasticity measuring device includes a vibrator, a driving unit, and a detection sensor. For phase estimation without multi-frequency PLL operation, the device performs quadrature detection to generate a complex baseband signal having an in-phase component I in phase with the drive signal and a quadrature component Q orthogonal to the drive signal. The device calculates the signal phase delay (Δ) from the complex baseband signal values (I, Q) and calculates the viscoelastic phase angle (δ) of the measurement liquid from the signal phase delay (Δ).
In device embodiments, arithmetic processing calculates an absolute value (ηab) of a complex viscosity from the complex baseband signal values (I, Q) together with resonance frequency-related quantities, driving force, and density parameters of the measurement liquid. Further, arithmetic processing calculates a complex viscosity coefficient (η*) and a complex rigidity modulus (G*) from the viscoelastic phase angle (δ) and the absolute value (ηab) of the complex viscosity.
Claims Coverage
The partial content includes three independent claims (for methods and devices), with inventive features centered on single-frequency resonance operation and computing viscoelastic phase and viscosity-related outputs from signal phase delay (Δ) and, in some embodiments, quadrature baseband values (I, Q) and/or amplitude (x00).
Immersed vibrator driven at air resonance and phase-delay measurement
A vibrator is immersed in a measurement liquid, a drive signal drives the vibrator at a resonance frequency (f00) of the vibrator in the air, vibration is detected by a detection sensor, and a signal phase delay (Δ) of a sensor output signal with respect to the drive signal is measured.
Phase difference and amplitude measurement to compute complex viscosity magnitude and viscoelastic phase angle
A device measures an amplitude (x00) in a measurement liquid at a resonance frequency (f00) of the vibrator in the air, measures a phase difference between a drive signal and a sensor output signal as a signal phase delay (Δ), and calculates an absolute value (ηab) of a complex viscosity from the amplitude (x00) while calculating a viscoelastic phase angle (δ) from the signal phase delay (Δ).
Quadrature detection to compute signal phase delay from I/Q and determine viscoelastic phase angle
A quadrature detection unit performs quadrature detection of a sensor output signal to generate a complex baseband signal having an in-phase component I in phase with the drive signal and a quadrature component Q orthogonal to the drive signal, and an arithmetic processing unit calculates a signal phase delay (Δ) from the complex baseband signal values (I, Q) and calculates a viscoelastic phase angle (δ) from the signal phase delay (Δ).
Across the independent claims, the core inventive coverage is the measurement of signal phase delay (Δ) relative to a drive signal at the vibrator’s air resonance frequency (f00), with viscoelastic phase angle (δ) derived from Δ and complex viscosity-related outputs derived from δ together with either amplitude (x00) or quadrature baseband values (I, Q).
Stated Advantages
Enables simpler, cheaper designs by resonance-based single-frequency operation without PLL.
Reduces measurement points.
Avoids PLL control by using single-frequency resonance and phase-delay-based computation.
Documented Applications
Tuning fork vibration viscometer.
Rotational vibration viscometer.
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