JPH02128142A - Optical fine particle measuring apparatus - Google Patents

Abstract

PURPOSE:To measure fine particles without causing lowering in grain size resolutions in a wide size range by projecting a measuring light to a flow cell made of a transparent material through which a fluid to be measured runs. CONSTITUTION:A first light receiving section 10 receives a transmission light 11 of a measuring light 6 transmitted through a flow cell 1 to output a first light reception signal 13a. A second light receiving section 16 receives a forward scattered light 17 caused by the irradiation of fine particles 2 in a fluid 3 to be measured in the flow cell 1 by the measuring light 6 and outputs a second light reception signal 19a corresponding to the results of light reception. A signal processing section 26 has signals 13a and 19a inputted thereinto and outputs a data signal 27 by a specified signal processing for the input signals. Then, since the signal 13a is a signal by a light shielding method while the signal 19a is a signal by a light scattering method, the number and a grain size distribution of the fine particles 2 can be measured by signals 15a and 15b with high grain size resolutions. This also enables measurement of the number and the grain size distribution of the fine particles 2 with high grain size resolutions by signals 24a and 24b.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a particle measurement method that detects the optical phenomenon that occurs when light is projected onto a fluid containing particles and measures the number and size distribution of particles during processing. Equipment, especially.

The present invention relates to an apparatus that has a small minimum particle size of measurable particles and can perform measurements over a wide particle size range with a higher particle size resolution.

[Conventional technology]

When measuring the number and particle size distribution of fine particles in a fluid (hereinafter, this measurement may also be referred to as the measurement of single particles), C is a conventional method for measuring fine particles using a light blocking method. A measuring device and a particle measuring device that employs a light scattering method are often used.
This measurement light passes through the fluid to be measured and the transmitted light is received and processed.

This appears in the amount of light received. The latter device measures the particle diameter and number of particles based on the degree of pulse-like light intensity reduction caused by the particles blocking the measurement light and the number of times this visual field decreases.

1. Receiving the scattered light of the measurement light generated by the particles when the measurement light is projected onto the flowing fluid to be measured containing the particles;
The size and number of fine particles are measured from the degree of pulse-like increase in the amount of light received and the number of times the amount of light increases.

[The problem that the invention attempts to solve]

When measuring particulates in a flowing fluid to be measured, conventionally, the two types of measuring devices mentioned above are often used.

When the particle size is large, the resolution of the particle size (hereinafter referred to simply as particle size resolution) is ) is high,
*Although it has the advantage of being able to obtain measurement results with less variation, C.

When the particle size of the fine particles is about 1 μm or less, the influence of light diffraction etc. increases, so there is a drawback that the measurement sensitivity, that is, the minimum particle size that can be measured with a predetermined particle size resolution, does not become very small. Soukou, again. Measurement devices that use the light scattering method include He*Ne lasers, semiconductor lasers, light-emitting diodes, etc.
When using light with a wavelength of nm slenderness as measurement light, 0.3
Although this method has the advantage of being sensitive to particles with a particle size as small as ~0.5 μm and being able to measure particles with a smaller particle size than a measuring device that adopts the two-light blocking method, When the particle size of the fine particles exceeds about I Am, there is a drawback that the resolution of the particle size of the fine particles decreases due to the Mie scattering phenomenon of light.

It is an object of the present invention to compensate for the above-mentioned drawbacks of a particle measuring device using a light blocking method and a particle measuring device using a light scattering method by applying each other to other measuring devices. To obtain a particulate measuring device that has sensitivity down to the lower limit particle size of 0.3 to 0.5 μm and has high particle size resolution over a wide particle size range with this lower limit particle size as the lower limit. be.

[Rotanu's means of solving problems]

In order to achieve the above object, the present invention includes a blow cell made of a transparent material through which a fluid to be measured flows, a light projecting section for projecting measurement light from the flow cell, and a transmission light of the measurement light transmitted through the flow cell. A first light receiving section that receives light and outputs a first light reception signal according to the result of the light reception; A second device receives forward scattered light that is scattered in a direction substantially in front of the direction in which the light travels, and outputs a second light reception signal in accordance with the result of this light reception.
a light receiving section; and a signal processing section to which the first and m2 light receiving signals are input, perform predetermined signal processing on these meat input signals, and output a data signal according to the result; Based on this, the number of fine particles in the fluid to be measured and the size distribution of fine rice grains are measured.

[Effect]

With the above configuration, the first light reception signal is a signal based on the light blocking method described above, and is therefore a signal that allows measurement results with high particle size resolution to be obtained for fine particles with a particle size of 1 μm or more. Further, the second light reception signal is a signal based on the above-mentioned light scattering method.

For this reason, from the lower limit particle size of about 0.3 to 0.5 μm to 1 μm
Because it is possible to obtain measurement results with high particle size resolution in the particle size range of fine particles up to a small particle size, it is possible to obtain a signal.

The data signal is set to a particle size of 0.3 to 0.5 μm as the lower limit.
It is possible to use a signal representing the result of fine particle measurement with high particle size resolution within a wide particle size range far beyond 1 μm, and as a result, it has sensitivity down to the lower limit particle size of 0.3 to 0.5 μm. Moreover, it is possible to obtain a particle measuring device that can measure particles over a wide particle size range with this lower limit particle size as the lower limit without causing a decrease in single particle size resolution.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of the main parts of FIG. 1. Figures 1 and 2 c
, 1 is a flow cell made of a transparent material and provided with a sample channel 4 having a square cross section through which a fluid to be measured 3 containing fine particles 2 flows perpendicularly to the paper surface of FIG. This flow cell 1 is formed into a rectangular prism shape so that the vertical cross section of the flow path 4 is coaxial with the axis of the flow path 4, which is the square shown in the figure. 512 flow cell 1 so that the measurement light 6, which is a parallel light beam, is projected perpendicularly to the -[plane ta<. A light source 7 such as a light emitting diode that emits light 7 m, a focusing lens 8 that focuses the light 7 m into -C measurement light 6, and a light source drive circuit 9 that controls the intensity of the light 7 m to a predetermined value. 10 is a first light receiving section configured to receive the transmitted light 11 of the measurement light 6 transmitted through the flow cell I.

This light receiving part! O is an aperture 12 that allows only the transmitted light 11 that has passed through the sample channel number to pass through and blocks other transmitted light ti, and the transmitted light 11 that has passed through this aperture 12.
A first light-receiving element 13 such as a photodiode is configured to receive light and output a first light-receiving signal 13m as a current signal corresponding to the amount of light received. in this case,
In order to irradiate the fluid to be measured 3 with a part of the measuring light 6 having a −-like light intensity distribution, the light projecting unit 5 and the light projecting unit 5 are arranged so that the optical axis of the light projecting unit 5 passes through the axis of the sample flow path 4 or its vicinity. flow cell l
Furthermore, since the aperture 12 is configured as described above, it is effective in improving the S/N ratio in the received light signal t3g.

! 4 converts the first light reception signal 1311 into a voltage signal, amplifies this voltage signal, and then converts the first signal t4a corresponding to the DC component in this amplified voltage signal and the amplified voltage signal into the above-mentioned voltage signal. gt outputs a signal excluding the DC component, that is, a second signal 14b having a temporal waveform corresponding to a temporal signal including a pulse waveform generated by the particle 2 blocking the measurement light 6; In the signal converter, the light source drive circuit 9 described above receives the first signal 14a and applies an appropriate operation amount 911 to the light source 7 to control the intensity of the light 7a represented by the signal 14a at a fixed value. Here, one pulse waveform exhibited by the signal 14b corresponds to one particle 2, and the peak value of the pulse waveform corresponds to the particle size of the particle 2. It is clear from the above that the second signal 14b and the first measurement condition signal 25m are inputted during the specified measurement time T by the first condition signal 25a. Count the number of Kero pulse waveforms 1"
c.

A first number multiple 15a corresponding to the number of particles 2 detected by the first light receiving section 10 during the time T is output, and
It is determined to which level band the peak value of the pulse waveform appearing in the signal 14b belongs to among the plurality of level bands set τ by the condition signal 25a, and C is the pulse that belongs to the same level band. By counting the number of C.

No. during time T! A first counting section that measures the particle size distribution of the fine particles 2 detected by the light receiving section 10 and outputs a first particle size distribution signal 15b according to the measurement result.

In this case, the counting unit 15 outputs the above-mentioned signal 15a only when the peak value of the pulse appearing in the signal 14b corresponds to the particle size of the fine particles 2 within the range of 1 to 30 μm.

15b.

16tX, when the particles 2 in the fluid to be measured 3 in the flow cell 1 are irradiated with the measurement light 6, forward scattered light is scattered by the particles 2 in the flow cell 1 in a direction substantially in the direction in which the measurement light 6 travels. 17 and 1. The second light receiving section outputs a second light receiving signal 191 which is a current signal corresponding to the light receiving result. an i-light lens 18 provided with a through hole tSa, a focusing lens 20 configured to condense 17% of the scattered light condensed by the lens 18, and make it incident on a second light receiving element 19 such as a photodiode; a second light receiving signal 19a that outputs the second light reception signal 19a according to the second light reception signal 19a;
It consists of a light receiving element 19 and an aperture 21.

Then, the first light receiving section 10 is placed inside the through hole 18a of the lens 18.

In addition, Aba Chiya 21t) is provided to limit the area where the second light receiving section 16 can receive light (hereinafter, this area may be referred to as the light receiving area).

Since the second light receiving section 16 has a busy structure as described above, its light receiving area is the light receiving surface of the lens 18, 20, the aperture 21, and the light receiving element 19! 9b and tl''C are formed in a spindle shape and are shaped like the area 22 shown in FIG. 2. Reference numeral 30 in FIG. In this case, each part is configured so that the sample channel 40 irradiated with the measurement light 6 is not included in the light receiving area 22, so if the measurement light 6 is irradiated with 1:fine particles 2, Of the scattered light emitted from the fine particles 2, the forward scattered light 17 directed toward the lens 18 shown in FIG.
In the M1 diagram, C is the scattered light 1 detected by the second light receiving section 16.
sample flow path 4 in which the emission area of 7 is irradiated with the measurement light 6;
0 part is busy.

That's it 1. In addition, in FIG. 1, the first light receiving section 10 is configured as Km and τ as described above. I want to.

In this case, the emission area of the transmitted light 11 detected by the first light receiving unit slO and the emission area of the scattered light 17 detected by the second light receiving section 16 are aligned.

23 receives the second light reception signal 19m, and this signal 19B
1! A second signal changing section 244' that outputs a time-lapse signal 23a corresponding to a signal obtained by removing the DC component from the amplified voltage signal after converting it into a voltage signal and amplifying it.
! The elapsed time signal 23a and the second measurement condition signal 25b are input, and the signal 238 is inputted during the measurement time T specified by the first condition signal 25b. The number of pulse waveforms based on the forward scattered light 17 by the particles 2 is counted and a second number multiple 24a corresponding to the number of particles 2 detected by the second light receiving section 16 during the 21:00 time period is outputted.

It is determined to which level band the peak value of the pulse waveform appearing in the signal 231 during time T belongs to among a plurality of level bands set by the condition signal 25bK.
C is the same level band VCI! ! Counting the number of the above-mentioned pulses, measuring the particle size distribution of the fine particles 2 detected by the second light-receiving section 6 for a period of time, and determining the second particle size according to this measurement result. The second counting unit outputs the distribution signal 24b, and this counting unit 24 outputs the signal 24a only when the peak value of the pulse appearing in the signal 238 corresponds to a particle size within the range of 0.3 to 1 μm. , 24t).

25 is configured to output the above-mentioned first measurement condition signal 2511 and second measurement condition signal 25b according to the setting operation ')'', depending on the appropriate setting operation such as key operation. In the measurement condition setting section 25, this setting section 25
By outputting 5a and 25b, the first and second
The counting units 15 and 24 are configured to simultaneously start the above-mentioned respective counting operations and simultaneously stop these counting operations, and 26 denotes the first and second signal converters 1.
4, 23, a first and second counting section 15, a signal processing section 24 and a measurement condition setting section 25; Distribution signal 1
5b and 24b, the signal processing unit 26
Since each part of the odor 'C is constructed as described above,
The processing unit 26 receives the first and second light reception signals 13111 19m
It can be said that these input signals are inputted and subjected to predetermined signal processing, and a data signal 27 corresponding to the result is output. So C, in this case.

It is clear from the foregoing that the number and particle size distribution of the particles 2 in the fluid to be measured 3 can be measured based on the data signal 271C. Reference numeral 28 denotes an optical particle measuring device consisting of the various parts shown in FIG.

In FIG. 1, C indicates that the particle measuring device 28 is configured as described above. Also, it is clear that the first light reception signal 13a is a signal obtained by the light blocking method and the wJ2 light reception signal 19a is a signal obtained by the light scattering method, so the signals 15a and 15b
The number and particle size distribution of fine particles 2 with a particle size of 1 to 30 μm can be measured with a particle size resolution 1 higher than that of K, and the signals 24a and 24b can be used to measure the number and particle size distribution of fine particles 21/2 with a particle size of 0.3 to 1 μm. The number and particle size distribution can be measured with a particle size resolution that is 1 higher than that of C. Yes, again. As described above, the emission region of the transmitted light 11 detected by the VC1 light receiving section 10 and the emission region of the scattered light 17 detected by the light receiving section 16 are the same. The measurement equipment is ft28.

It has sensitivity to the minimum particle size of 0.3 μm for the fluid 3 to be measured in the sample flow path 4, and has a sensitivity of 0.3 μm.
It is possible to measure Jinjiko 2 over a very wide range of particle sizes, from the lower limit particle size of 3 μm to the upper limit particle size of 30 μm, without causing a decrease in particle size resolution. be.

Then, C1, and C in the 6g3 constant device 28.

The second light reception signal 1911 obtained by the light scattering method is the forward scattered light 17.
Using the forward scattered light, the particle size resolution is better than when using the side scattered light emitted in a direction almost perpendicular to the optical axis of the measurement light 6. Generally, good particle measurement results can be obtained. Therefore, even in terms of the type of scattered light, the measuring device 28 has the advantage of improving the particle size resolution in particle measurement based on the second light reception signal t9m. [Effects of the Invention] As described above, one The odor sensor of the invention includes a flow cell made of a transparent material through which a fluid to be measured flows, a light projector that projects measurement light onto the flow cell, and a light projector that receives the transmitted light of the measurement light that has passed through the flow cell and responds to the result of the received light. 1) The first light receiving part that outputs the light reception signal and the particulates in the fluid to be measured in the flow cell are irradiated with the measuring light. A second light receiving section receives the forward scattered light and outputs a second light receiving signal as a result of this light reception, and a second light receiving section receives the first and second light receiving signals. A signal processing section that performs signal processing and outputs a data signal according to the result, and an optical particle sensor that measures the number of particles and the particle size distribution of the particles in the fluid to be measured based on this data signal. The measuring device was constructed.

Therefore, with the above configuration, the first light reception signal is a signal based on the light blocking method described above, and therefore the particle size is 1 μm.
It is a signal that allows measurement results with high particle size resolution to be obtained for fine particles of the above-mentioned size.

Further, the second light reception signal is a signal based on the above-mentioned light scattering method, particularly a method using forward scattered light, and therefore 0.3 to 0.
．． Since this is a signal that allows measurement results with high particle size resolution to be obtained in the particle size range from the lower limit particle size of 5 μm + 1 degree to a particle size of about 1 μm, the data signal can be adjusted to 0.3~0.
With a particle size of 5 μm as the lower limit, it is possible to obtain a signal representing the result of fine particle measurement with high particle size resolution within a wide particle size range exceeding 11 μrnyt, and as a result, 1. It has sensitivity down to the lower limit particle size of 0.5 μm and can measure fine particles over a wide particle size range with this lower limit as the lower limit without causing a decrease in particle size resolution. There are benefits to be gained.

In addition, in the present invention, since the first light reception signal is a signal based on the light blocking method and the second light reception signal is a signal based on the light scattering method, it is possible to use both light reception signals to simultaneously measure the same particle. By configuring the signal processing section, it is possible to simultaneously obtain two types of measurement results (particulate measurement results). This has the effect that highly reliable measurement results can be obtained when particles are stuck or when the concentration of particulates in the fluid to be measured is low.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a simple embodiment of the present invention, and FIG. 2 is an enlarged view of the main parts of FIG. 1. l...flow cell, 2...fine particles, 3
....Fluid to be measured, 5.....Light emitter, 6.
...Measurement light, 10...First light receiving section,
11...Transmitted light, 13a...11g1
Light reception signal, 16 second light reception section, 17... forward scattered light, 19a... second light reception signal, 26...
... Signal processing section, 27: ... Data signal. 28...Optical particle measuring device. Atsushi

Claims (1)

[Claims] 1) A flow cell made of a transparent material through which a fluid to be measured flows, a light projecting section that projects measurement light onto the flow cell, and a first light projecting section that receives the transmitted light of the measurement light that has passed through the flow cell and responds to the result of this light reception. A first light receiving section that outputs a light reception signal, and particles in the fluid to be measured in the flow cell are irradiated with the measurement light, and are scattered by the particles substantially in the forward direction in the direction in which the measurement light travels. a second light receiving section that receives the forward scattered light and outputs a second light receiving signal according to the result of the light reception; and a second light receiving section that receives the first and second light receiving signals and performs predetermined signal processing on both of these input signals. and a signal processing unit that outputs a data signal according to the result, and measures the number of particles and the particle size distribution of the particles in the fluid to be measured based on the data signal. measuring device.