JP4018956B2 - Particle size distribution measuring device and signal detection method in particle size distribution measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a particle size distribution measuring device and a signal detection method in the particle size distribution measuring device.
[0002]
[Prior art]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 7-311204
Conventionally, when measuring the particle size distribution with a particle size distribution measuring device, the sample to be measured is dispersed and stirred in a dispersion medium such as water to form a suspension, and this suspension is used for circulation such as a centrifugal pump or a perista pump. Scattered light or diffracted light is supplied to the flow cell by a pump and the suspension in the flow cell is irradiated with laser light in that state, and the detector detects the intensity distribution of these lights. Processing was performed based on the scattering theory to determine the particle size distribution of the sample.
[0003]
In the particle size distribution measuring apparatus, since it is necessary to detect the liquid level for further automation, conventionally, the amount of suspension has been detected using a liquid level sensor using a float or the like. As the liquid level sensor, an electrode type, an optical type, a capacitance type, a float type or the like is generally known. (See Patent Document 1) These liquid level sensors determine whether the amount of suspension satisfies a predetermined amount suitable for dispersion by the ultrasonic vibrator, and the flow rate of the dispersion medium injected into the dispersion bath. By controlling the injection time, the suspension was controlled to be a predetermined amount.
[0004]
[Problems to be solved by the invention]
However, each of the liquid level sensors has the following drawbacks. That is, in the case of the electrode type, the liquid level cannot be detected when a dispersion medium such as alcohol that does not conduct electricity is used, and in the case of the capacitance type, the dielectric constant varies greatly depending on the dispersion medium, so accurate measurement cannot be performed. On the other hand, there is a problem that the optical liquid level sensor cannot be measured accurately due to dirt, and the float type liquid level sensor is clogged with the sample to be measured in the sliding part of the float part, or due to wear etc. There is a problem that malfunction may occur and there is no texture compared to other types of liquid level sensors.
[0005]
On the other hand, in the particle size distribution measuring apparatus, it is usually performed by irradiating the suspension with ultrasonic waves and applying appropriate vibration so that the particles of the sample to be measured in the suspension are not solidified. If the ultrasonic vibrator is driven in the absence of turbid liquid, the ultrasonic vibrator itself is damaged, or the ultrasonic waves that are originally applied to disperse the sample to be measured in the suspension are in another part of the device ( For example, there is a concern that the particle size distribution measuring device may be damaged by acting on a dispersion bath tank. For this reason, the ultrasonic transducer is interlocked so that it operates only when the liquid level sensor detects the presence of the suspension, but the liquid level sensor malfunctions. This may cause a problem that the ultrasonic transducer operates despite the absence of the suspension.
[0006]
In addition, the ultrasonic vibrator has a capability of being lowered or fluctuated depending on the dispersion medium to be dispersed, its temperature, the type and concentration of particles contained in the dispersion medium. In addition, the vibrator attached to the ultrasonic vibrator is consumed, and when the vibrator is consumed due to long-term use, the original dispersion ability may not be exhibited.
[0007]
For this reason, in order to determine whether or not the operation of ultrasonic dispersion is operating normally, the user of the device is responsible for the sound generated from each part in the device by the oscillation of the ultrasonic transducer. I checked it with my ears. However, it takes a lot of experience and skill to determine the oscillation state of an ultrasonic transducer. liquid Of the sample to be measured may not be normally dispersed. In addition, the ultrasonic dispersion was performed by dispersing the sample to be measured at a predetermined intensity according to the ultrasonic dispersion level and time set by the user of the apparatus. However, if normal dispersion is not performed, the dispersion state is not sufficient. In this state, the sample to be measured is measured, and the measurement result may be adversely affected.
[0008]
The present invention has been made in consideration of the above-mentioned matters, and its purpose is to detect the liquid level of the suspension of the dispersion medium containing the sample to be measured and to disperse the sample to be measured. Of particle size distribution measuring apparatus and particle size distribution measuring apparatus capable of preventing breakage of ultrasonic transducers, and performing self-diagnosis of ultrasonic transducers to disperse samples to be measured with appropriate strength It is to provide a detection method.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the particle size distribution measuring apparatus of the present invention comprises a dispersion bath in which a sample to be measured is dispersed in a dispersion medium to form a suspension, and ultrasonic waves are applied to the suspension in the dispersion bath. When irradiating the suspension in the flow cell with ultrasonic irradiation means for irradiating and promoting dispersion of the sample to be measured, and a circulation channel connecting the dispersion bath and the flow cell In the particle size distribution measuring device for obtaining the particle size distribution of the measurement target sample by detecting the light generated in the ultrasonic wave, at least at the lower end portion of the dispersion bath at a position affected by the ultrasonic wave irradiated from the ultrasonic wave irradiation means The ultrasonic signal of the ultrasonic wave or the suspension vibrated by this ultrasonic wave is attached to the inner wall surface. detection And a suspension in a dispersion bath using a sound wave signal detected by the detection means Detect the liquid level of the suspension Amount of And when it is detected that the amount of the obtained suspension is necessary and sufficient for ultrasonic dispersion, the ultrasonic irradiation means should be driven and controlled for a predetermined time so as to disperse the sample to be measured. Based on the computing means for computing and the sound wave signal, Output from ultrasonic irradiation means And calculating means for performing feedback control so as to detect the state of the ultrasonic wave and to keep the output of the ultrasonic wave irradiation means constant Calculation Part It is characterized by having. (Claim 1)
[0010]
That is, the vibration generated by the ultrasonic wave applied to the suspension from the ultrasonic irradiation means is detected using the detection means, and the liquid level and the amount of the suspension in the flow cell are detected to detect the liquid level. Since it is possible to both disperse the sample to be measured in the suspension and to detect the liquid level without providing a separate ultrasonic irradiation means as a transmitter, the installation space for the ultrasonic irradiation means can be reduced and installed. This leads to a reduction in the number of parts.
[0011]
In addition, as a detection means for detecting ultrasonic waves and vibrations as sound wave signals, for example, a relatively inexpensive device such as an acoustic detector such as a microphone is used. Therefore, in addition to reducing the number of components, expensive components are not required. Thus, the manufacturing cost can be reduced. The liquid level detection for detecting the amount of suspension in the present invention includes not only detecting the position of the liquid level but also detecting the presence or absence of the suspension.
[0012]
Furthermore, since the liquid level is detected by transmission of ultrasonic waves and vibrations of the suspension caused thereby, there is no fear of malfunction due to dirt or abrasion due to powder, and the reliability of the particle size distribution measuring apparatus can be improved accordingly. In addition, since the liquid level can be detected without being affected by the type of suspension (conductivity, dielectric constant, etc.), the liquid volume of the suspension can always be obtained accurately. As a result, the amount of liquid in the circulating layer can be adjusted as appropriate, and malfunction due to malfunction of the liquid level sensor and damage inside the apparatus due to driving of the ultrasonic irradiation means in the absence of suspension can be reliably prevented. .
[0013]
As the position affected by the ultrasonic wave, for example, a detection unit such as an acoustic detector or an acceleration sensor is provided at the position of the counter electrode that receives the vibration of the ultrasonic wave. Can be received directly. In addition, by providing an acoustic detector, etc., at the position where the sound wave reflected by the liquid surface is received as the position affected by the ultrasonic wave, the delay time from when the ultrasonic wave is oscillated to when the sound wave reflected by the liquid surface is received is reduced. It becomes possible to detect the liquid volume of the suspension.
[0014]
Furthermore, the position affected by the ultrasonic waves is not limited to the position where the suspension is touched, and the sound waves and vibrations generated by the irradiation of the ultrasonic waves can be improved even outside the suspension container or flow path. If it can be detected, it can be attached at any position.
[0015]
When the detection means detects the intensity and / or frequency of the sound wave signal (Claim 2), it is suspended depending on the intensity of the sound wave signal detected using the difference in the transmission rate of the sound between the liquid and the gas. The liquid volume of the liquid can be determined, and the liquid volume of the suspension can be determined based on the frequency of the sound wave signal detected using the difference in resonance frequency determined by the liquid volume of the suspension.
[0016]
The computing means is the intensity of the sound wave signal; frequency, At least one of the delay times Of the liquid level of the suspension in the dispersion bath and the intensity, frequency, and delay time of the sound wave signal In the case of having a storage unit for storing a relationship with at least one as a calibration curve (Claim 3), erosion (consumption) of the vibrator occurs, and vibration of the oscillation unit does not reach the suspension sufficiently. Sometimes, the calculation means can make a diagnosis by quantifying the dispersion ability of the ultrasonic irradiation means. There is a special vibrometer that detects the magnitude of the amplitude of the vibrator numerically. However, in the present invention, the ultrasonic irradiation means is suspended by an inexpensive detection means without using such special equipment. It is possible to determine the dispersion ability of the ultrasonic irradiation means by quantifying the strength of the influence on the suspension.
[0017]
Then, the dispersion power can be kept constant by adjusting the power supplied to the ultrasonic irradiation means by feeding it back so that the intensity of the ultrasonic wave generated from this ultrasonic irradiation means is constant. Can be stabilized. Furthermore, when the ultrasonic wave of a predetermined intensity cannot be irradiated due to the erosion of the vibrator, it can be diagnosed that the vibrator cannot be used. That is, the vibrator diagnosis unit can know the deterioration and life of the vibrator.
[0018]
The positions affected by the ultrasonic waves include, for example, the position of the counter electrode that receives ultrasonic vibrations, the position that receives the sound waves reflected by the liquid surface, and the outside of the suspension container and the flow path. However, any position can be selected as long as vibrations generated by ultrasonic irradiation can be detected satisfactorily.
[0019]
The signal detection method in the particle size distribution measuring apparatus of the present invention includes a dispersion bath in which a sample to be measured is dispersed in a dispersion medium to form a suspension, and ultrasonic waves are applied to the suspension in the dispersion bath. Light that is generated when the suspension in the flow cell is irradiated with light, including ultrasonic irradiation means for promoting dispersion of the sample to be measured, and a circulation channel that connects the dispersion bath and the flow cell. In the particle size distribution measuring apparatus for obtaining the particle size distribution of the sample to be measured by detecting the at least the inner wall surface at the lower end of the dispersion bath at a position affected by the ultrasonic waves irradiated from the ultrasonic irradiation means. The ultrasonic wave or a sound wave signal of the suspension vibrated by the ultrasonic wave is detected, and the suspension in the dispersion bath is detected from the detected sound wave signal. Detecting the liquid level of the suspension amount And when it is detected that the amount of the obtained suspension is necessary and sufficient for ultrasonic dispersion, the ultrasonic irradiation means should be driven and controlled for a predetermined time so as to disperse the sample to be measured. While calculating, based on the sound wave signal Ultrasonic irradiation means From Output Is calculated to perform feedback control so as to keep the output of the ultrasonic irradiation means constant. It is characterized by that. (Claim 4)
[0020]
In other words, a method for detecting the amount of suspension includes a dispersion bath in which a sample to be measured is dispersed in a dispersion medium to form a suspension, and a flow cell connected via a circulation channel to the suspension in the flow cell. In the particle size distribution measuring device that determines the particle size distribution of the sample to be measured by detecting the light generated by irradiating light, when the suspension is irradiated with ultrasonic waves to promote the dispersion of the sample to be measured In addition, a sound wave is detected at a position affected by the ultrasonic wave, and the liquid level of the suspension is detected using a detection signal of the sound wave.
[0021]
In addition, a method for detecting the deterioration state of the ultrasonic irradiation means is a method in which a dispersion bath and a flow cell, in which a sample to be measured is dispersed in a dispersion medium and suspended, are connected via a circulation channel, and suspended in the flow cell. In the particle size distribution measuring device that determines the particle size distribution of the sample to be measured by detecting the light generated by irradiating the liquid with light, the suspension is irradiated with ultrasonic waves to promote dispersion of the sample to be measured In this case, a sound wave signal is detected at a position affected by the ultrasonic wave, and the state of the ultrasonic oscillation source is detected using the sound wave signal.
[0022]
On the other hand, as a control method of the particle size distribution measuring apparatus, a dispersion bath in which a sample to be measured is dispersed in a dispersion medium and used as a suspension is connected to a flow cell via a circulation channel, and a suspension in the flow cell is obtained. In the particle size distribution measuring device that determines the particle size distribution of the sample to be measured by detecting the light generated by irradiating the sample with light, the suspension was irradiated with ultrasonic waves to promote the dispersion of the sample to be measured Sometimes, a sound wave signal is detected at a position affected by this ultrasonic wave, and control is performed using this sound wave signal to keep the output of the ultrasonic oscillation source constant.
[0023]
That is, based on the detected sound wave signal, the vibration capability of the ultrasonic irradiation means is detected, the ultrasonic intensity is fed back, and the ultrasonic vibration output is monitored and controlled. By keeping the output of the oscillation source constant, dispersion can always be performed with the same intensity, and the reproducibility of the measurement is improved.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing an example of the overall configuration of a particle size distribution measuring apparatus 1 of the present invention. In FIG. 1, a particle size distribution measuring apparatus 1 of this example includes a measuring unit 1a and a calculation unit 1b configured by a calculation processing device such as a personal computer.
[0025]
2 is a sample to be measured, 3 is distilled water (hereinafter referred to as dispersion medium 3) as an example of a dispersion medium, and 4 is a sample to be measured 2 dispersed in the dispersion medium 3 Hanging It is a turbid liquid, 5 is this Hanging A dispersion bath for generating (or adjusting) the turbid liquid 4, 6 is a flow cell, and 7 is a circulation channel that connects the dispersion bath 5 and the flow cell 6 in communication. 8 is an ultrasonic irradiation means (ultrasonic transducer) provided on the bottom surface of the dispersion bath 5, for example, and 9 is a microphone as an example of an acoustic detector constituting the detection means (for example, an audio frequency higher than or equal to an audio frequency) A water-resistant hydrophone that can receive ultrasonic waves is desirable, but is simply referred to as a microphone 9 in the following description.
[0026]
Reference numeral 10 denotes a container for accommodating the dispersion medium 3, and 11 denotes a dispersion medium supply means for pumping the dispersion medium 3 from the container 10 and supplying it to the dispersion bath 5. That is, by operating the dispersion medium supply means 11 for a predetermined time, the dispersion medium 3 can be supplied into the dispersion bath 5, and these containers 10 and the dispersion medium supply means 11 are suitable for measuring the particle size distribution. An automatic diluting device is configured that can dilute the suspension 4 so as to obtain a proper concentration.
[0027]
12 is a centrifugal pump for stirring the sample to be measured while circulating the dispersion medium in the circulation flow path 7, 13 is a motor for supplying rotational force to the centrifugal pump 12, and 14 is the suspension 4 in the dispersion bath 5. A drainage portion 15 for discharging the surplus suspension 4 when the amount of the liquid becomes too large, and a drainage portion 15 for discharging all the suspensions 4 in the circulation channel 7.
[0028]
Reference numeral 16 denotes a light source for irradiating the suspension 4 in the flow cell 6 with light such as laser light, and reference numeral 17 denotes a light receiver. Although only one light receiver 17 is shown in FIG. 1 for ease of explanation, actually, a plurality of light beams reflected and / or reflected at a plurality of angles with respect to the light irradiation angle are received. The light is received by the device 17.
[0029]
In the particle size distribution measuring apparatus 1 of the present invention, it is important that the microphone 9 is attached at a position affected by the ultrasonic wave from the ultrasonic vibrator 8, and in this example, for example, the inner side at the lower end of the dispersion bath 5 The example which consists of the 1st microphone 9a provided so that it may become flush with the wall surface of this and the 2nd microphone 9b provided so that it may become flush with the inner wall surface slightly lower than the said drainage part 14 is shown.
[0030]
Since both the microphones 9a and 9b face the inner wall surface of the dispersion bus 5 that can directly receive the ultrasonic waves from the ultrasonic vibrator 8, the ultrasonic waves from the ultrasonic vibrator 8 are directly used as sound waves. The signals Sa and Sb can be detected. When the microphone 9 is immersed in the suspension 4, strong ultrasonic waves can be detected as the sound wave signals Sa and Sb. When the microphone 9 is not immersed in the suspension 4, weak ultrasonic waves attenuated by air are detected as the sound wave signal Sa. , Sb.
[0031]
Further, since the first microphone 9a is provided at the lower end portion of the dispersion bus 5, when the first microphone 9a detects weak ultrasonic waves as the sound wave signal Sa, the suspension 4 is almost contained in the dispersion bus 5. It shows no. On the other hand, since the second microphone 9b is provided slightly below the drainage portion 14 of the dispersion bath 5, when the second microphone 9b detects a strong ultrasonic wave as the sound wave signal Sb, the suspension in the dispersion bus 5 4 can be detected to be overflowing.
[0032]
The calculation unit 1b receives the sound wave signals Sa and Sb from both the microphones 9a and 9b, and compares the magnitudes of the sound wave signals Sa and Sb with an appropriate threshold value. The presence or absence of the suspension 4 can be determined. That is, the calculation unit 1b is a calculation unit that detects the liquid level 4a using the sound wave signals Sa and Sb, and has a function as a liquid level detection unit.
[0033]
The computing unit 1b supplies the dispersion medium 3 into the dispersion bus 5 by driving the dispersion medium supply means 11 while monitoring the liquid level 4a, and uses the ultrasonic vibrator 8 to suspend the suspension medium 5 in the dispersion bus 5. By irradiating the suspension 4 with ultrasonic waves, the sample 2 to be measured is dispersed, and by driving the motor 13, all the suspensions 4 in the circulation channel 7 can be mixed and stirred. Then, the calculation unit 1b irradiates the suspension 4 diluted to a concentration suitable for the measurement of the particle size distribution with a laser beam using the light source 16, and scatters the suspension 4 in the flow cell 6 using the light receiver 17. By detecting the scattered light, / or the analytical calculation of the particle size distribution of the sample to be measured can be performed.
[0034]
In the present embodiment, the detection sensitivity is improved as much as possible by providing the microphone 9 so as to face the inner peripheral surface of the dispersion bus 5, and the accumulation of the sample 2 to be measured can be achieved by attaching the microphone 9. The turbulent flow of the suspension 4 is not formed. However, the present invention does not limit the installation positions and number of microphones 9 to those shown in this example. That is, the microphone 9 can be installed anywhere as long as it can detect sound waves and vibrations from the suspension 4 generated by the ultrasonic waves generated from the ultrasonic vibrator 8. In this case, the ultrasonic transducer is driven at the position where the microphone is attached, and the relationship between the detected sound wave signal and the amount of suspension (liquid level height) in the dispersion bath can be obtained in advance by experiments or the like. desirable.
[0035]
FIG. 2 is a diagram conceptually showing the principle of liquid level detection using the microphones 9a and 9b. FIG. 2A is an example of a portion affected by the ultrasonic wave from the ultrasonic vibrator 8. FIG. 2B is a diagram showing a change in the configuration and state of each part centered on the bus 5, and FIG. 2B shows an ultrasonic wave U irradiated from the ultrasonic transducer 8 in this state and a sound wave signal detected by the microphones 9a and 9b. It is a figure which shows the relationship with Sa and Sb.
[0036]
In FIG. 2, the ultrasonic wave U emitted from the ultrasonic vibrator 8 or the sound wave of the suspension 4 vibrated by the ultrasonic wave U (hereinafter, the ultrasonic wave U is also expressed as a sound wave for the sake of simplicity. ) Propagates in the distribution bus 5 as indicated by arrows a to h in FIG. 2A, and among the arrows a to h, propagation of sound waves indicated by solid lines occurs in the suspension 4 and sound waves indicated by dotted lines. Propagation of air shall occur in the atmosphere.
[0037]
As shown in FIG. 2B, the ultrasonic wave U irradiated from the ultrasonic vibrator 8 is output only momentarily in a pulse manner, and this propagates through the dispersion medium 4 or the air in the dispersion bath 5 to make the microphones 9a and 9b. Detected.
[0038]
When the suspension 4 does not exist in the dispersion bath 5, the microphones 9a and 9b use the ultrasonic wave U that has propagated the air as indicated by the arrows a and b as the sound wave signal Sa. ₁ , Sb ₁ These sound wave signals Sa are detected as ₁ , Sb ₁ Is less likely to propagate than in the liquid. For this reason, it is significantly attenuated with respect to the original ultrasonic wave U. Also, the sound wave signal Sa ₁ , Sb ₁ Detects the ultrasonic wave U that has propagated in the atmosphere, so that the signal is delayed with respect to the original ultrasonic wave U.
[0039]
Next, when there is some suspension 4 in the dispersion bath 5, each microphone 9a has an ultrasonic wave U that has propagated straight through the suspension 4 as indicated by an arrow c, and an arrow d. Thus, the sound wave reflected by the liquid surface 4a or the like is detected. Therefore, the microphone 9a is a strong sound wave signal Sa that propagates through the suspension 4 at high speed. ₂ And a somewhat delayed sound wave signal Sa ₂ 'And detect. On the other hand, as indicated by an arrow e, the microphone 9b propagates through the suspension 4 partway and detects a sound wave that has propagated through the atmosphere later. That is, the microphone 9b is somewhat attenuated and delayed by the sound wave signal Sb. ₂ Is detected.
[0040]
Finally, when there is a suspension 4 that overflows in the dispersion bath 5, each microphone 9a has an ultrasonic wave U that has propagated straight through the suspension 4 as indicated by an arrow f, and an arrow h. As shown, a sound wave reflected by the liquid surface 4a or the like is detected. Therefore, the microphone 9a is a strong sound wave signal Sa that propagates through the suspension 4 at high speed. _Three And the sound wave signal Sa ₂ Sound wave signal Sa delayed for a longer time than ' _Three 'And detect. On the other hand, the microphone 9b transmits the sound wave signal Sb which has propagated through the suspension 4 and hardly attenuated as indicated by an arrow g. _Three Is detected.
[0041]
That is, the arithmetic unit 1b receives the sound wave signals Sa and Sb from the microphones 9a and 9b, so that the presence or absence of the suspension 4 in the dispersion bath 5 and the suspension 4 are likely to overflow from the drainage unit 14 from the strength. It can be judged whether it is in a proper state. That is, the calculation part 1b functions as a liquid level detection part.
[0042]
In this example, the liquid level 4a is detected by using two microphones 9a and 9b at the position of the lower end portion of the dispersion bath 5 and the position just before the drainage portion 14, so that the liquid level can be determined only by the intensity of the sound wave signals Sa and Sb. Even if the surface 4a is determined, for example, there are three stages: “a state where there is no suspension”, “a state where there is a certain amount of suspension”, and “a state where the suspension is filled enough to overflow” It is possible to distinguish which state the suspension 4 is in. Further, by increasing the number of microphones 9, it is possible to detect the liquid level 4a in more stages.
[0043]
Further, the calculation unit 1b can obtain the natural vibration of the suspension 4 using the frequencies of the sound wave signals Sa and Sb, and can detect the amount of the suspension 4 therefrom. In this case, the calculation unit 1b functions as a liquid level detection unit that detects the liquid level of the suspension 4 using the frequencies of the sound wave signals Sa and Sb. And when performing the liquid level detection using the frequency of the sound wave signals Sa and Sb, it is not necessary to limit to providing a plurality of microphones 9, and only a single microphone 9 may be attached to the lower end of the distribution bus 5. .
[0044]
Further, the sound wave signal Sa ₂ ', Sa _Three It is also possible to detect the position of the liquid level 4a from the length of the delay time '. Also in this case, it is not limited to providing a plurality of microphones 9. Then, by using all the intensities, frequencies, and delay times of the sound wave signals Sa and Sb for the determination of the liquid level detection, it is possible to detect the position of the liquid level 4a with higher accuracy.
[0045]
In addition, even when the liquid level 4a is detected by any of the above methods, the sound wave signals Sa and Sb are detected in advance using some dispersion medium, and the height of the liquid level 4a and the intensity of the sound wave signals Sa and Sb are detected. It is desirable to store the relationship with the frequency, delay time, etc. in the calculation unit 1b as a calibration curve. Thereby, the detection accuracy of the liquid level 4a can be increased.
[0046]
It is also possible to obtain the amount of the suspension 4 accurately by detecting the liquid level 4a, for example, by making the shape of the dispersion bath 5 into a vertically long cylinder. That is, in the measurement of the particle size distribution, it is necessary to adjust by decreasing the concentration by adding the dispersion medium 3 or the like so that the concentration of the suspension 4 is suitable for the measurement. It is also possible to calculate the amount of the added dispersion medium 3 by using the surface detection method and obtain the concentration of the suspension 4.
[0047]
In addition, the state of the ultrasonic transducer 8 is diagnosed using the sound wave signals Sa and Sb detected by the microphones 9a and 9b of this example. That is, the sound wave signal Sa in FIG. ₂ , Sa _Three As described above, the specific signal in the state where the suspension 4 is put is used to detect the magnitude of the amplitude of the ultrasonic wave transmitted from the ultrasonic vibrator 8 as a numerical value. That is, when the vibrator of the ultrasonic vibrator 8 is eroded and wear proceeds, the vibrator cannot transmit sufficient vibration. This state is indicated by the sound wave signal Sa. ₂ , Sa _Three Can be detected accurately.
[0048]
Then, by detecting the amplitude of the ultrasonic wave using the relatively inexpensive microphone 9 as in the present invention, the manufacturing cost can be reduced as compared with the case of installing a dedicated amplitude meter. In addition, the calculation unit 1b of this example functions as a vibrator diagnosis unit that diagnoses the state of the ultrasonic vibrator 8 using the sound wave signals Sa and Sb detected by the microphones 9a and 9b.
[0049]
Further, the sound wave signal Sa ₂ , Sa _Three It is also possible to apply feedback to the ultrasonic transducer 8 by supplying electric power to the ultrasonic transducer 8 so that becomes a predetermined intensity. At this time, even when the maximum power is supplied to the ultrasonic transducer 8, the sound wave signal Sa ₂ , Sa _Three Is not a predetermined strength, the life of the ultrasonic transducer 8 is displayed on the display D of the calculation unit 1b, and the user can be prompted to replace the ultrasonic transducer. .
[0050]
FIG. 3 is a diagram for explaining the movement of each part in a series of operations for particle size distribution measurement performed by the particle size distribution measuring apparatus 1.
[0051]
As shown in FIG. ₀ When the user stores the sample to be measured in the dispersion bath 5 and starts the measurement, first, the dispersion medium supply means 11 moves to the time t. ₁ The dispersion medium 3 is injected into the dispersion bath 5 for a predetermined time until the time t ₁ ~ T ₂ The liquid level 4a of the suspension 4 is detected by irradiating pulsed ultrasonic waves using the ultrasonic vibrator 8 in a short period of time. In this example, time t ₁ ~ T ₂ In the detection of the liquid level in the meantime, it is assumed that the microphone 9a detects that the amount of the suspension 4 is not sufficient although it is immersed in the suspension 4.
[0052]
Here, if the user tries to drive the ultrasonic transducer 8, the calculation unit 1b warns the user by displaying on the display D that the amount of the suspension 4 is not sufficient. To do.
[0053]
Next, at time t ₂ ~ T _Three In the meantime, the dispersion medium supply means 11 is further driven to inject a sufficient amount of the dispersion medium 3 into the dispersion bath 5. Also, since some suspension 4 is present in the dispersion bath 5, the time t ₂ Then, the pump 12 is operated to diffuse the suspension 4 by circulation.
[0054]
Next, the particle size distribution measuring apparatus 1 _Three ~ T _Four In the meantime, a second liquid level detection is performed to determine whether the amount of the suspension 4 is sufficient. In this example, in the second liquid level detection, it is detected that there is a sufficient amount of the suspension 4 for ultrasonic dispersion, and the time t _Five ~ T ₆ The sample to be measured is dispersed using the ultrasonic vibrator 8 at a predetermined time. At this time, the microphone 9 detects the sound wave generated by the irradiation of the ultrasonic wave from the ultrasonic vibrator 8 and feeds back the operation unit 1b so that the intensity of the ultrasonic wave output from the ultrasonic vibrator 8 is constant. multiply.
[0055]
That is, by irradiating ultrasonic waves at a predetermined intensity for a predetermined time, predetermined dispersion can be caused and the state of the suspension 4 can be adjusted. And time t ₇ ~ T ₈ In the meantime, the calculation unit 1 b irradiates the suspension 4 with light using the light source 16 and detects the intensity of scattered light and / or diffracted light at each angle using the light receiver 17. Further, the particle size distribution of the measurement target sample 2 is calculated using the light intensity distribution for each angle.
[0056]
When the measurement of the particle size distribution is completed, time t ₉ Thereafter, the suspension 4 after measurement is discharged using the drainage unit 15.
[0057]
【The invention's effect】
As described above, according to the present invention, the ultrasonic transducer for dispersing the sample (particle) to be measured in the suspension in the dispersion bath and the inexpensive acoustic detector are extremely simple. With a simple configuration, it is possible to detect the amount of suspension in the dispersion bath and to perform liquid level detection with excellent robustness and reliability. It is possible to reliably prevent the ultrasonic vibrator from being driven in a state where there is no suspension that may cause damage. Further, it is possible to accurately obtain the intensity of the ultrasonic wave output from the ultrasonic transducer using the same acoustic detector, and it is possible to always irradiate the ultrasonic wave having the same intensity.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a particle size distribution measuring apparatus of the present invention.
FIG. 2 is a diagram illustrating the principle of detecting the liquid level.
FIG. 3 is a diagram illustrating a series of operations related to measurement of particle size distribution.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Particle size distribution measuring apparatus, 1b ... Calculation means (calculation part), 2 ... Sample to be measured, 3 ... Dispersion medium (distilled water), 4 ... Suspension, 4a ... Liquid surface, 5 ... Dispersion bath, 6 ... Flow cell, 7 ... circulation flow path, 8 ... ultrasonic irradiation means (ultrasonic transducer), 9 (9a, 9b) ... detection means (microphone), Sa, Sb ... acoustic wave signal, U ... ultrasonic wave.

Claims (4)

Dispersion bath in which a sample to be measured is dispersed in a dispersion medium to form a suspension, and ultrasonic irradiation to promote dispersion of the sample to be measured by irradiating the suspension in the dispersion bath with ultrasonic waves Means, and a circulation channel connecting the dispersion bath and the flow cell, and detecting the light generated when the suspension in the flow cell is irradiated with light, thereby determining the particle size distribution of the sample to be measured. In the desired particle size distribution measuring device,
Attached to the inner wall surface at least at the lower end of the dispersion bath at a position affected by the ultrasonic wave emitted from the ultrasonic wave irradiation means, and detects the ultrasonic wave signal of the ultrasonic wave or a suspension vibrated by the ultrasonic wave. Detecting means for
Using the sound wave signal detected by the detection means, the liquid level including the presence or absence of the suspension in the dispersion bath is detected to determine the amount of the suspension, and the obtained suspension amount is the ultrasonic dispersion. When it is detected that it is necessary and sufficient for the measurement, the ultrasonic wave is calculated on the basis of the sound wave signal and the calculation means for performing drive control of the ultrasonic wave irradiation means for a predetermined time so as to disperse the sample to be measured. A particle size distribution measuring apparatus comprising: a calculation unit having a calculation unit that detects a state of an output from the irradiation unit and performs feedback control so as to keep the output of the ultrasonic irradiation unit constant .   2. The particle size distribution measuring apparatus according to claim 1, wherein the detecting means detects the intensity and / or frequency of the sound wave signal. Said calculating means, the intensity of the acoustic signal, the frequency, intensity from at least one of the height and the wave signal of the liquid surface of the suspension in the dispersion bath sought among the delay time, frequency, delay time of at least 1 The particle size distribution measuring apparatus according to claim 1, further comprising a storage unit for storing a relationship between the two as a calibration curve. Dispersion bath in which a sample to be measured is dispersed in a dispersion medium to form a suspension, and ultrasonic irradiation to promote dispersion of the sample to be measured by irradiating the suspension in the dispersion bath with ultrasonic waves Means, and a circulation channel connecting the dispersion bath and the flow cell, and detecting the light generated when the suspension in the flow cell is irradiated with light, thereby determining the particle size distribution of the sample to be measured. In the desired particle size distribution measuring device,
Detecting a sound wave signal of the ultrasonic wave or a suspension vibrated by the ultrasonic wave at an inner wall surface at a lower end of the dispersion bath at a position affected by the ultrasonic wave irradiated from the ultrasonic wave irradiation unit;
From the detected sound wave signal, the liquid level of the suspension in the dispersion bath is detected to determine the amount of the suspension, and it is detected that the obtained amount of suspension is necessary and sufficient for ultrasonic dispersion. Then, the ultrasonic irradiation means is operated to drive and control over a predetermined time so that the sample to be measured is dispersed, and the state of the output from the ultrasonic irradiation means is detected based on the sound wave signal. A signal detection method in a particle size distribution measuring apparatus, wherein the calculation is performed so as to perform feedback control so as to keep the output of the ultrasonic wave irradiation means constant .

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