WO2019012815A1 - Foam characteristic measurement system - Google Patents

Abstract

The present invention makes it possible to obtain a general-purpose foam characteristic measurement system capable of objectively measuring the characteristics of foam regardless of the type of sample. A drive unit 12 causes a vibrating element 11 immersed in a foam layer 112 to vibrate in accordance with a drive signal. A sensor unit 13 detects the vibration of the vibrating element 11. A mechanical impedance identification unit 22 uses the drive signal and the output signal of the sensor unit 13 to calculate the mechanical impedance received by the vibrating element 11 from the foam. A foam characteristic identification unit 23 measures the foam characteristics of the foam layer 112 on the basis of the calculated mechanical impedance.

Description

Foam characteristic measurement system

The present invention relates to a foam characteristic measurement system.

An objective evaluation of foam characteristics (such as foam retention) is desired in various industries such as food-related, cosmetic-related and oil-chemical related. As a method of evaluating foam characteristics, for example, a flow-down method adopted in JIS-K3362 regarding foam retention (foam stability) of synthetic detergent, an air supply method adopted in JIS-K2518 regarding foam stability of lubricating oil, etc. Test methods of have been proposed.

Moreover, the measuring apparatus which evaluates foam retention of a beer by specifying the relationship between foam layer thickness and foam retention time is proposed (for example, refer patent document 1).

International Publication No. 1999/030149

The above-mentioned method observes the temporal change of the bubbles due to the sample from the outside of the container etc., and evaluates the foam characteristics of the sample by the unique measurement method according to the type of each sample. Because it changes depending on the characteristics of the sample, in the above method, it is necessary to establish a measurement method for each type of sample, and for samples of types for which there is no established measurement method, objectively It is difficult to identify the characteristics. In addition, in the food-related and cosmetic-related cases, when the lather is visually observed, it takes about one hour for the observation time, and the burden is large and man-hours are also required.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a general-purpose foam characteristic measurement system capable of objectively measuring the foam characteristic regardless of the type of sample.

The foam characteristic measurement system according to the present invention comprises a vibrator immersed in a foam layer, a drive unit for vibrating the vibrator according to a drive signal, a sensor unit for detecting vibration of the vibrator, an output of the drive signal and the sensor unit The mechanical impedance specifying unit that calculates the mechanical impedance of the foam layer from the signal, and the foam characteristic specifying unit that measures the foam characteristic of the foam layer based on the calculated mechanical impedance.

According to the present invention, regardless of the type of sample, the drive time of the vibrator can be shortened, so that the general-purpose foam can objectively measure the characteristics of the foam while reducing the influence on the foam due to the vibration of the vibrator. A characteristic measurement system is obtained.

FIG. 1 is a view showing the configuration of a foam characteristic measurement system according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of temporal change of mechanical impedance in the first embodiment. FIG. 3 is a diagram showing an example of two-dimensional coordinates by the attenuation coefficient of the real component of the mechanical impedance and the attenuation coefficient of the imaginary component in the second embodiment. FIG. 4 is a diagram showing an example of a locus of mechanical impedance in the complex number plane in the third embodiment.

Hereinafter, embodiments of the present invention will be described based on the drawings.

Embodiment 1

FIG. 1 is a view showing the configuration of a foam characteristic measurement system according to an embodiment of the present invention.

The sample (liquid) is separated into the liquid layer 111 and the foam layer 112 in the container 101, and the foam property measuring system shown in FIG. 1 measures the foam property of the foam layer 112.

The foam characteristic measurement system shown in FIG. 1 includes a probe unit 1, a fixing base 2 for fixing the probe unit 1, a signal conversion unit 3, and a signal processing unit 4.

The probe unit 1 includes a vibrator 11, a drive unit 12, and a sensor unit 13.

The vibrator 11 includes a shaft 11 a and a spherical portion 11 b at the end of the shaft 11 a. The spherical portion 11 b is immersed in the foam layer 112. The spherical portion 11b is, for example, a metal sphere, but may be other material such as resin (synthetic resin) or PTFE (Polytetrafluoroethylene), as long as it is sufficiently rigid to the target bubble.

The drive unit 12 vibrates the vibrator 11 in the vertical direction (that is, in the depth direction perpendicular to the surface of the foam layer) according to the drive signal. For example, the drive unit 12 includes a solenoid coil, applies a drive signal to the solenoid coil, and vibrates the vibrator 11 at the same frequency as the drive signal. In addition, you may vibrate the vibrator | oscillator 11 in the diagonal direction with respect to the surface of a foam layer not only in an up-down direction.

The sensor unit 13 detects the vibration of the vibrator. Here, the sensor unit 13 detects the acceleration of the vibrator 11 with, for example, a piezoelectric element, and generates an acceleration signal indicating the detected acceleration.

For example, it is desirable that the spherical portion 11b has a diameter of 5 mm, the diameter of the shaft 11a be sufficiently small, and not more than about 1⁄5 of the spherical diameter of the spherical portion 11b. Here, it is 0.6 mm. The drive unit 12 vibrates the vibrator 11 at a resonance frequency of about 300 Hz. The resonance frequency is a resonance frequency found by sweeping the vibration frequency in a state where the vibrator is not immersed in the measurement target (in the air). By driving the drive unit 12 using this resonance frequency, it is possible to perform measurement with high sensitivity. However, although the sensitivity decreases, it is not necessary to limit the condition of the vibration frequency to resonance.

For the probe unit 1, for example, the one described in Japanese Patent No. 5020403 can be used.

The signal conversion unit 3 includes an analog amplifier, a digital analog converter, an analog digital converter, and the like. The signal conversion unit 3 converts a drive signal as a digital signal from the signal processing unit 4 into an analog signal, amplifies it as necessary, and then supplies the drive signal to the drive unit 12 of the probe unit 1. Further, the signal conversion unit 3 amplifies an acceleration signal as an analog signal from the sensor unit 13 of the probe unit 1 as necessary, and then converts it into a digital signal, and supplies the acceleration signal to the signal processing unit 4 Do.

The signal processing unit 4 is a computer such as a personal computer including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), etc., and is stored in a ROM, a storage device (not shown) The program is loaded into the RAM and executed by the CPU, thereby operating as various processing units.

Here, the signal processing unit 4 operates as the drive signal output unit 21, the mechanical impedance specifying unit 22, the bubble characteristic specifying unit 23, and the timer unit 24.

The drive signal output unit 21 generates a drive signal of a predetermined frequency and supplies the drive signal to the drive unit 12 of the probe unit 1 via the signal conversion unit 3.

The mechanical impedance identification unit 22 calculates the mechanical impedance of the foam layer 112 from the drive signal and the output signal of the sensor unit 3. Here, the mechanical impedance specifying unit 22 acquires an acceleration signal from the sensor unit 3 of the probe unit 1 via the signal conversion unit 3 and calculates the mechanical impedance of the foam layer 112 from the drive signal and the acceleration signal.

For example, as described in Japanese Patent No. 5020403, the mechanical impedance specifying unit 22 has a phase difference θ _L between the drive signal and the acceleration signal and the drive signal and the acceleration signal when the vibrator 11 is immersed in the foam layer 112. Amplitude ratio | F _L | with the (a) phase difference θ _A between the drive signal and the acceleration signal and the amplitude ratio between the drive signal and the acceleration signal | when the vibrator 11 is placed in the air F _A |, and (b) the phase difference θ _L between the drive signal and the acceleration signal and the amplitude ratio | F _L | between the drive signal and the acceleration signal when the vibrator 11 is immersed in the foam layer 112 retardation theta _a, the phase difference is the difference of _{θ L γ (= θ a -θ} L), and the amplitude ratio _{| F a |, | F L} | amplitude ratio is the ratio of _{α (= | F a | /} | F _L |) to identify, mechanical impedance Zx the (complex) in the following equation Calculate I.

It is assumed that the phase difference θ _A between the drive signal and the acceleration signal and the amplitude ratio | F _A | between the drive signal and the acceleration signal are measured in advance when the vibrator 11 is disposed in the air. Further, since the mechanical impedance Zp depends only on the vibration frequency of the vibrator 11 and the mechanism of the measurement system such as the probe unit 1, it is a constant here and, for example, an experiment etc. as described in Japanese Patent No. 5020403. Are specified in advance.

The foam property specifying unit 23 measures the foam property of the foam layer 112 based on the measured mechanical impedance.

Further, the timer 24 sets a time interval in which the vibrator vibrates and a time interval in which the vibration is stopped, and manages a series of operation times in the measurement. For example, the measurement time is 10 seconds, the measurement cycle is 1 minute, and the bubble characteristic measurement system operates according to the number of times of measurement. Specifically, when the number of measurements is one, by setting the number of measurements as one, a drive signal is input to the drive unit 12 for 10 seconds, and the spherical portion 11 b is vibrated to measure the mechanical impedance. Stop. In addition, in the case where the number of measurements is two, when the first time is started, a drive signal is input to the drive unit 12 for 10 seconds to vibrate the spherical portion 11 b to measure mechanical impedance. The next 50 seconds stop and then a second measurement takes 10 seconds to stop. As described above, since the vibration time of the spherical portion 11 b can be shortened, the measurement can be performed with almost no influence of the vibration of the spherical portion 11 b on the foam layer 112. In addition, when looking at the passage of time in the measurement of foam characteristics, it is necessary to compare the measurement results under the same conditions, so it is possible not only to automatically monitor the progress by using a timer, but also to other samples. Measurement of the same condition can be easily performed.

In the embodiment to be described later, it is desirable to measure under a constant environment of temperature and humidity.

In the first embodiment, the bubble characteristic specifying unit 23 specifies (a) a model expression that indicates a temporal change of mechanical impedance as an exponential decay, and (b) based on the attenuation coefficient β in the model expression. The foam characteristics related to the foam retention of the foam layer 112 are measured. In this measurement, the number of times of measurement may be set to several times (two to five times), and estimation can be made in a considerably short time as compared with visual observation.

The model equation is, for example, the following equation.

Y = Y ₀ · exp (β · (t-t ₀ )) + Y ₁

Here, Y is the value of the imaginary or real component of the mechanical impedance, Y ₀ is the initial value of the attenuation term Y ₀ · exp (β · (t−t ₀ )), and β is the attenuation coefficient And t ₀ is an offset value which is the time from the end of bubbling to the start of measurement, and Y ₁ is an offset value.

Then, the bubble characteristic specifying unit 23 measures, for example, the measured values of the imaginary number component or the real number component of the mechanical impedance at a plurality of timings from the start of measurement until the predetermined time elapses The values of regression coefficients (constants) Y ₀ , β, t ₀ , and Y ₁ of a model equation (nonlinear regression equation) are specified by predetermined nonlinear regression analysis processing on serial data). For example, Generalized Reduced Gradient (GRG) non-linear can be used as non-linear regression analysis processing.

FIG. 2 is a diagram showing an example of temporal change of the real component of the mechanical impedance in the first embodiment. In FIG. 2, the sample A is a stock solution of a hand soap having relatively good bubbling and lathering, and the sample B is a stock solution of non-added soap having relatively low bubbling and lathering.

In FIG. 2, the model formula of sample A is Y = 4.104 · exp (−0.002518 · (t + 58.10)) − 2.553, and the model formula of sample B is Y = 5.311 · exp. (−0.007436 · (t + 54.37)) − 2.536. The measurement value of the imaginary component of the mechanical impedance is normalized by the measurement value at the start of measurement (t = 0), and the regression coefficient is specified based on the normalized measurement value.

That is, the attenuation coefficient β of the sample A is −0.002518, and the attenuation coefficient β of the sample B is −0.007436. The absolute value of the attenuation coefficient β of the sample A is smaller than the absolute value of the attenuation coefficient β of the sample B. As described above, the damping coefficient β of a sample having a good bubble resistance has a smaller absolute value.

Therefore, the foam characteristic specifying unit 23 may set the attenuation coefficient β as the foam characteristic value of the foam layer 112, or obtain in advance the correspondence between the attenuation coefficient and the existing characteristic value such as foam retention, This attenuation coefficient may be converted to an existing characteristic value based on the correspondence relationship.

Next, the operation of the foam characteristic measurement system according to the first embodiment will be described.

First, a sample is prepared, and the liquid layer 111 and the foam layer 112 are formed in a predetermined procedure. Next, the probe unit 1 is disposed such that the spherical portion 11 b of the vibrator 11 is immersed in the foam layer 112.

Next, the drive signal output unit 21 of the signal processing unit 4 generates a drive signal and supplies the drive signal to the drive unit 12 of the probe unit 1 without passing through the signal conversion unit 3. The drive unit 12 vibrates the vibrator 11. Thereby, the spherical portion 11 b vibrates up and down in the foam layer 112.

The sensor unit 13 of the probe unit 1 supplies an acceleration signal corresponding to the vibration to the signal processing unit 4 via the signal conversion unit 3.

In the signal processing unit 4, the mechanical impedance specifying unit 22 measures the mechanical impedance received from the foam by the vibrator 11 immersed in the foam layer 112 based on the acceleration signal and the drive signal, and the foam characteristic specifying unit 23 measures it. Based on the obtained mechanical impedance, the foam characteristics relating to the foam retention of the foam layer 112 in which the vibrator 11 is immersed are measured.

In the first embodiment, the mechanical impedance specifying unit 22 measures the mechanical impedance at each point in time along the time series, and the bubble characteristic specifying unit 23 determines the temporal change of the measured mechanical impedance. As described above, the value of the attenuation coefficient β is specified. Furthermore, if necessary, the foam property identifying unit 23 converts the value of the attenuation coefficient β into the value of the existing foam properties (such as foam retention).

As described above, according to the first embodiment, the drive unit 12 vibrates the vibrator 11 immersed in the foam layer 112 according to the drive signal, and the sensor unit 13 detects the acceleration of the vibrator 11. An acceleration signal indicating the detected acceleration is generated. The mechanical impedance identification unit 22 measures the mechanical impedance of the foam from the drive signal and the acceleration signal, and the foam characteristic identification unit 23 measures the foam characteristics relating to foam retention of the foam layer 112 based on the measured mechanical impedance. .

Thereby, regardless of the type of sample, it is possible to objectively measure the characteristics of the bubble. That is, since the mechanical impedance of the vibrator 11 is measured in a state where the vibrator 11 is immersed in the foam layer 112, a machine that changes according to the physical properties (viscosity, elasticity, mass, etc.) of the foam formed by the sample. By measuring the foam characteristics related to bubble retention from the impedance, a versatile foam characteristics measurement system can be obtained.

Second Embodiment

In the bubble characteristic measuring system according to the second embodiment, the mechanical impedance specifying unit 22 specifies the real component and the imaginary component of the mechanical impedance of the vibrator 11, and the bubble characteristic specifying unit 23 performs the (a) real component of the mechanical impedance. (1) specify a first model equation that indicates the temporal change of L as an exponential decay, and identify a second model equation that indicates a temporal change of the imaginary component of the mechanical impedance as an exponential decay; The foam characteristics of the foam layer relating to the stability of the foam are measured based on two-dimensional coordinates based on the damping coefficient β _r in one model equation and the damping coefficient β _i in the second model equation.

That is, in the second embodiment, the same attenuation coefficient as that of the first embodiment is derived for both the real component and the imaginary component of the mechanical impedance, and a pair of the real component attenuation coefficient β _r and the imaginary component attenuation coefficient β _i The foam characteristics of the foam layer relating to the stability of the foam are measured depending on which one of a plurality of regions divided in advance in the two-dimensional plane the two-dimensional coordinate indicated by.

FIG. 3 is a diagram showing an example of two-dimensional coordinates according to the attenuation coefficient β _r of the real component of the mechanical impedance and the attenuation coefficient β _{i of the} imaginary component in the second embodiment. In the example shown in FIG. 3, the two-dimensional plane is divided into a stable area and an unstable area by a predetermined boundary line, and the two-dimensional coordinates of the damping coefficient of sample A belong to the stable area. Is determined to be stable, and since the two-dimensional coordinate of the attenuation coefficient of the sample B belongs to the unstable region, the bubble retention of the sample B is determined to be unstable. In addition, since the types of samples are various, the boundary line may be set so as to be able to be evaluated according to each type.

The other configurations and operations of the foam characteristic measurement system according to the second embodiment are the same as those of the first embodiment, and thus the description thereof will be omitted.

As described above, according to the second embodiment, the bubble characteristic of the sample is identified from the two-dimensional coordinates of the attenuation coefficient β _r of the real component of the mechanical impedance and the attenuation coefficient β _{i of the} imaginary component for each sample. Therefore, by setting the target area in advance, it is possible to evaluate the sample by measuring the foam characteristics relating to the stability of the foam by whether or not the two-dimensional coordinates belong to the area. it can.

Third Embodiment

In the bubble characteristic measuring system according to the third embodiment, the mechanical impedance specifying unit 22 measures the real component and the imaginary component of the mechanical impedance that the vibrator 11 receives from the foam, and the bubble characteristic specifying unit 23 measures the complex component plane. The position of the coordinate of mechanical impedance or the locus of mechanical impedance is measured as the foam characteristics of the foam layer relating to the feel and texture of the foam.

For example, the signal processing unit 4 displays the locus of the mechanical impedance on a complex display on a predetermined display device or prints it on a recording sheet.

For the real component of the mechanical impedance, as the real component of the mechanical impedance is larger, the viscosity of the foam film becomes stronger, and for the imaginary component of the mechanical impedance, if the imaginary component of the mechanical impedance is positive, the mass of the foam film dominates If the imaginary component of the mechanical impedance is negative, then the elasticity of the foam film will dominate. Therefore, it is possible to grasp the temporal change of the bubble characteristic relating to the touch and texture of the bubble by the locus of the mechanical impedance in the complex number plane.

FIG. 4 is a diagram showing an example of a locus of mechanical impedance in the complex number plane in the third embodiment.

For example, although the foam of sample A shown in FIG. 4 is strong initially and is dominated by mass, over time, the stickiness weakens and elasticity becomes dominant. In addition, the foam of sample B shown in FIG. 4 is weaker than the sample A in initial viscosity, and elasticity does not increase much with time.

The other configuration and operation of the foam characteristic measurement system according to the third embodiment are the same as those of the first embodiment, and thus the description thereof will be omitted.

As described above, according to the third embodiment, the temporal change of the bubble characteristic relating to the touch or texture of the bubble is evaluated by the position of the measured mechanical impedance coordinate in the complex number plane or the locus of the mechanical impedance. be able to.

Fourth Embodiment

In the foam characteristic measurement system according to the fourth embodiment, the vibrator 11 is changed in the depth direction of the foam layer, and the mechanical impedance identification unit 22 determines the mechanical impedance value at each point (one of the real component and the imaginary component). Or the both values are measured, and the bubble characteristic specifying unit 23 specifies (a) a change in mechanical impedance when the vibrator 11 is changed in the depth direction of the foam layer 112, and (b) the mechanical impedance The distribution of the foam characteristics of the foam layer 112 in the depth direction of the foam layer 112 (for example, the water content distribution in the depth direction of the foam layer 112) is identified based on the change in.

The other configuration and operation of the foam characteristic measurement system according to the fourth embodiment are the same as those of the first embodiment, and thus the description thereof will be omitted.

Note that various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing the intended advantages. That is, such changes and modifications are intended to be included in the scope of the claims.

The invention is applicable, for example, to the measurement of foam properties of various samples.

11 oscillator 12 drive unit 13 sensor unit 22 mechanical impedance identification unit 23 bubble characteristic identification unit 24 timer

Claims (6)

1. A vibrator immersed in the foam layer,
   A drive unit that vibrates the vibrator according to a drive signal;
   A sensor unit that detects the vibration of the vibrator;
   A mechanical impedance identification unit that calculates mechanical impedance of the foam layer from the drive signal and an output signal of the sensor unit;
   A foam characteristic specifying unit that measures the foam characteristic of the foam layer based on the calculated mechanical impedance;
   A bubble characteristic measurement system comprising:
2. The system further comprises a timer that sets a vibrating time interval of the vibrator and manages a series of operation time in measurement;
   The sensor unit detects an acceleration of the vibrator.
   The mechanical impedance specifying unit calculates mechanical impedance that the vibrator receives from foam from the drive signal and an acceleration signal of the sensor unit.
   The bubble characteristic measurement system according to claim 1, comprising:
3. The foam characteristic identifying unit identifies (a) a model equation that indicates temporal change of the mechanical impedance as an exponential decay, and (b) the foam associated with bubble retention based on the attenuation coefficient in the model equation. The system for measuring foam properties according to claim 1, characterized in that the foam properties of the layer are measured.
4. The mechanical impedance identification unit calculates a real component and an imaginary component of the mechanical impedance,
   The bubble characteristic specifying unit specifies (a) a first model expression that indicates temporal change of the real component of the mechanical impedance as exponential decay, and an exponential function of the temporal change of the imaginary component of the mechanical impedance. The second model formula shown as the dynamic damping is specified, and (b) the stability of the bubble is determined based on the two-dimensional coordinates of the damping coefficient in the first model formula and the damping coefficient in the second model formula Measuring the foam properties of the foam layer,
   The bubble characteristic measurement system according to claim 1, characterized in that
5. The mechanical impedance identification unit calculates a real component and an imaginary component of the mechanical impedance,
   The foam characteristic specifying unit measures the position of the coordinate of the mechanical impedance and / or the locus of the mechanical impedance in the complex number plane as the foam characteristic of the foam layer relating to the touch and texture of the foam,
   The bubble characteristic measurement system according to claim 1, characterized in that
6. The foam characteristic identification unit (a) calculates a change in the mechanical impedance when changing the vibrator in the depth direction of the foam layer, and (b) the foam based on the change in the mechanical impedance. The system for measuring foam characteristics according to claim 1, wherein the distribution of foam characteristics of the foam layer in the depth direction of the layer is measured.

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