JPS6337234A - Apparatus for measuring particle in fluid - Google Patents

Abstract

PURPOSE:To measure particles real time, by counting the photoelectron pulses of laser scattering beams due to particles in a fluid and providing (M+1) pulse count circuits corresponding to the addition number M of times in the moving average processing thereof to successively operate the same. CONSTITUTION:Laser beam 1 is condensed to the fluid in a measuring area 3 and scattering beams due to particles are allowed to reach a photomultiplier tube 7 and the output of the photomultiplier tube 7 is inputted to a pulse wave form shaping circuit 10. The circuit 10 is connected to pulse count circuits 21-2(M+1) to count pulses. Then, count operation is performed by the signal from a shift register 51 and a count value is latched by latch circuit 31-3(M+1) and subsequently compared with a set value by a comparator 55. At this time, the pulse count circuits 21-2(M+1) are successively operated. That is, (M+1) pulse count circuits are provided corresponding to the addition number M of times in the moving average processing of photoelectron pulse count to be successively operated and, therefore, a particle characteristic can be measured real time in a fluctuation reduced state.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention is a particle measuring device in a fluid, and more specifically, a particle diameter and number density of particles mixed in a fluid is measured using a photon counting method. related to a device for

[Prior Art] Conventionally, in such an apparatus, a fluid containing particles in an 11 g constant cell is irradiated with a laser beam, and particle characteristics are determined using the scattered light using a photomultiplier tube.

In this case, as the particle size of the particles mixed in the fluid becomes smaller, the scattered light from the laser-irradiated particles becomes weaker. It is known that using a photon counting method is a more effective means for detecting weak light than using a photomultiplier tube in an analog manner.

First, a conventional device will be explained using FIG. 4.

In FIG. 4, laser light emitted from a laser light source 1 is focused onto a measurement area 3 by a lens 2. In FIG. The measurement region 3 is the inside of the measurement cell 4 through which fluid is flowing.

When particles pass into the measurement region, they scatter the incident laser light. The light scattered by the particles is focused by a lens 5 and formed into an image on a slit 6. The light passing through the slit reaches the photocathode of the photomultiplier tube 7. At this time, if light is considered as a particle, that is, a photon, the photon that reaches the photocathode causes electrons to be emitted from the photocathode due to the photoelectric effect. The electrons emitted from the photocathode are converted into 1 inside the photomultiplier tube 7.
The signal is amplified by about 0.6 times and becomes the output signal of the photomultiplier tube.

This output signal is amplified by a preamplifier 8 and passed through a pulse height discriminator 9. The threshold value of the pulse height discriminator is set to the lower limit of the voltage or current corresponding to the signal when only one electron is emitted from the photocathode of the photomultiplier tube. When the signal amplified by the preamplifier 8 is higher than the threshold of the pulse height discriminator 9, the pulse height discriminator 9 outputs a pulse.

The pulse waveform of this pulse is adjusted by the pulse waveform shaping circuit 10 and output as a photoelectronic pulse. The method of counting these photoelectron pulses is the photon counting method. In the photon counting method, the intensity of scattered light from one particle corresponds to the number of photoelectron pulses per unit time. Therefore, by counting the number of photoelectron pulses within a certain time interval, the particle size and number density of particles in the fluid can be determined from the counted value.

However, as the diameter of the particles mixed in the fluid becomes smaller, the scattered light from the particles irradiated with laser light becomes weaker, and the process of emitting photons from the particles becomes stochastic. Therefore, the fluctuation of the 91 numerical value of the number of photoelectron pulses per unit time becomes large. This fluctuation poses a problem when determining particle characteristics. Arithmetic processing is required to visually reduce fluctuations in the count value of photoelectron pulses and make it easier to determine particle characteristics.

A moving average method is effective as this calculation processing method. To explain the moving average method, a certain time Δ from a certain time t
Let N (t) be the number of photoelectron pulses counted during t.

Hereinafter, this Δt will be referred to as sample time. The number of photoelectron pulses counted between t+Δt and t+2・Δt is N(t+
1). In this representation method, 1-1+Δt N(t)t+Δ
t-t+2・Δt N(t+1)t+2・Δt-
t+3・Δt N(t+2)t+・Δt−t+(k
+1) Reference Δt N (t+k). Here, M is the number of additions. When such processing is performed, fluctuations in the photoelectron pulse count value can be seen.
1=can be made smaller, making it easier to determine particle characteristics.

In the conventional method, as shown in FIG.
, the counted value is stored in the memory circuit 12, and the counted value is read in by the arithmetic unit, and a moving average calculation process is performed.

[Problems to be Solved by the Invention] In the conventional method as described above, in order to reduce the apparent fluctuation in the count value of photoelectron pulses, the count value of photoelectron pulses is calculated by a calculation device using a moving average method. If processed,
Computation time is required. That is, it becomes impossible to determine the particle size and number density of particles in the fluid in real time.

Therefore, the present invention was made to solve such problems, and it calculates a moving average in real time to reduce the apparent fluctuation of the count value of photoelectron pulses by photon counting method. The purpose of the present invention is to provide a particle measuring device that can measure the particle meter and number density of particles in real time.

[Means for Solving the Problems] In the present invention, in order to solve the problems described in -1-, moving average processing is performed on the counts of photoelectron pulses obtained from laser scattered light from particles in the fluid. An apparatus for measuring particles in a fluid that determines the characteristics of particles by detecting the characteristics of the particles, the apparatus comprises: a laser light source that irradiates a laser beam into a fluid in which particles flow; a means for receiving laser scattered light from the particles and converting it into an electrical signal; pulse generating means that converts the signal from the converting means into a number of pulses corresponding to the scattered light intensity; and (M-)'1) for counting the pulses from the pulse generating means and corresponding to the number of additions M of the moving average processing. a pulse counting circuit; means for controlling the (M+1) pulse counting circuits; a comparator for comparing the counted value of the pulse counting circuit with a preset value; The apparatus is equipped with a 31 number circuit that counts by 1, and employs a configuration in which moving average processing is performed in real time by sequentially operating the (M+1) pulse counting circuits to perform particle measurement.

[Function] In such a configuration, (M+1) counting circuits are used for pulse counting, and since the (M+1) counting circuits are controlled by an (M+1) bit shift register, the moving average is Processing can be performed in real time, and the particle diameter and number density of particles contained in a fluid can be measured in real time using photon counting method.

[Example] Hereinafter, an example of the present invention will be described in detail using FIGS. 1 to 3.

FIG. 1 shows the configuration of the apparatus of the present invention, and in FIG. 1, the same parts as in FIG. 4 are given the same reference numerals, and the explanation thereof will be omitted.

In the device of the present invention, up to the point where the photoelectron pulse is obtained, the fourth
It is the same as the figure device.

1- Equation (1) representing the moving average described above corresponds to counting photoelectron pulses at time E for a time period of M·Δt. That is, if photoelectron pulses are counted for a time period of MφΔt, 5(to) at time to can be obtained. Furthermore, by using (M+1) counting circuits, the time change of S (t) can be measured.

For this purpose, as shown in FIG. 1, (M+1) pulse counting circuits 21, 22 . ...2(M+1) are provided. Each pulse counting circuit is connected to a pulse waveform shaping circuit lO via a NAND circuit, and a shift register 51
Count operations are performed in response to signals from count output terminals (1, 2, . . . M+1) of , and the counted values are sent to latch circuits 31, 32, . ...Latch at 3(M+1). Selection circuits 41, 42 .・
...4(M+1) is connected, and the count value latched in the latch circuit is sent to the comparator 55 according to the selection signal.
and the results are counted by a counter 56.

Further, a reference clock generator 54 for generating a reference clock for counting is provided, and the reference clock is inputted to the timer signal generation circuit 52 via the local frequency generator 53.
A signal from the timer signal generation circuit 52 is input to a timer one terminal of the shift register 51.

A detailed circuit diagram when the number of additions M of the moving average is set to two is shown in FIG. Identical parts in FIG. 1 are given the same numbers. Since the number of additions to obtain the moving average is two, three pulse 51 number circuits 21 to 23 and a 3-bit shift register 51 are provided.

The operation of the counting device having such a configuration will be explained with reference to the timing chart of FIG.

A photoelectron pulse corresponding to the particle scattered light obtained from the pulse waveform shaping circuit 10 is input to the terminal 72 . A reference clock obtained from the reference clock generator 56 is inputted to a terminal 71, and is frequency-divided by a frequency dividing circuit 53 to generate a clock C2. Here, the reference clock and clock CI are the same signal. Further, one period of the clock C2 becomes the sample time Δt.

This clock C2 is a synchronous presettable 4 bit 2
The signal is input to a timer signal generation circuit 52 consisting of a forward counter, and a timer signal TM is output. This timer signal TM determines the counting time of the photoelectron pulses of the pulse counting circuits 21-23. Now, since we have set the number of additions to 2,
The counting time of photoelectron pulses corresponding to the number of additions is two periods of the clock C2. Therefore, the timer signal TM is at a high level during two cycles of the clock C2, becomes low level during one cycle of the next clock C2, and repeats this operation. - When adding arbitrary M times in the shell, if the data input to the synchronous presettable 4-bit binary counter 52 is M, the timer signal is at high level for M periods of the clock C2, and the next One cycle of the clock C2 becomes a low level and becomes a signal that repeats this operation.

The timer signal TM and clock C2 are inputted to the shift register 51, and a count T is output from the terminals QO, Ql, and Q2.
l, count T2. A control signal for count T3 is created;
Each pulse 81 is input to number circuits 21-23. Count Tl, count T2, and count T3 are control signals involved in counting photoelectron pulses, and when these control signals are at the noise level, pulse counting circuits 21 to 23 involved in each control signal count photoelectron pulses. Count. When these control signals are at low level, the pulse counting circuits 21 to 23 involved in each control signal,
The pulse counting circuit 21 does not count the photoelectron pulses.
The corresponding latch circuits 31 to 33 latch the count values of .about.23, and set the pulse counting circuits 21 to 23 to the initial state. The temporal relationship between the count Tl, the count T2, and the count T3 is that after the count T1 becomes high level, the count T2 becomes high level after a delay of one period of the clock C2, that is, a time Δt corresponding to the sample time. Further, after the count T2 becomes high level, the clock signal T3 becomes high level with a delay of one period of the clock C2. With this control method, S (t)
It is possible to find the change over time.

Count TI, count T2. Count T3 is inverted by inverters 61 to 63, respectively, and select S1, select S2 . Select S3 is formed. Sereno) Sl
, S2. S3 is a control signal that selects a pulse counting circuit that inputs the photoelectron pulse count value to the comparator 55. Therefore, these control signals prevent more than one Norse counting circuit from being selected at the same time. When these control signals are at high level, the count value of photoelectron pulses is input to the comparator 55.

Latch Ll, latch L2. The latch L3 transfers the count value counted by the pulse counting circuits 21 to 23 to the latch circuits 31 to 3.
This is a control signal for latching at 3. The count value of the Nonolus counter circuit when these control signals are at /\high level is latched. Latch Ll is the reference clock and clock C
It becomes high level when all the signals of 2 and Serenoto Sl become high level. Similarly, latch L2 goes to /\\y level when all the signals of the reference clock, clock C2, and select S2 go to high level, and latch L3 goes to high level when all the signals of reference clock, clock C2, and select S3 go to high level. When this happens, the signal becomes high level and is input to the latch circuits 31 to 33, respectively.

Also, clock C2, each count TI, count T2.
Count) A reset signal R1 that sets the pulse counting circuits 21 to 23 that count photoelectron pulses from T3 to the initial state,
R2 and R3 are formed.

When these signals are at a high level, the corresponding Norms counting circuits are set to their initial state. RESET/)R1 becomes high level when clock C2 and count Tl become low level at the same time. Similarly, reset R2 goes high when clock C2 and count T2 go low at the same time, and reset R3 goes high when clock C2 and count T3 go low at the same time.

Select Sl, Select S2. The count value of the photoelectron pulse of each pulse counting circuit 21 to 23 selected by the selection S3 is input to the comparator 55. In this comparator,
Set so that a high level signal is output when a count value larger than preset data is input. Even if a count value larger than the preset data is continuously input to the comparator, the output signal from the comparator 55 remains at a high level. When a count value smaller than the preset data is input to the comparator, the output signal from the comparator becomes low level. The counter 56 counts as the output signal from the comparator changes from high level to low level. Here, the data set in advance in the comparator 55 corresponds to the particle diameter of particles in the fluid.

Accordingly, the count value displayed on the display 65 is a value related to the number density of particles in the fluid.

Furthermore, by employing a plurality of comparators, it is also possible to measure the number density of a plurality of particle diameters.

Further, in the embodiment, the number of times of addition of the moving average is assumed to be two, but it goes without saying that this number of times of addition can be extended to any number of M times.

[Effects of the Invention] As explained above, according to the present invention, (M+1) pulse counting circuits corresponding to the number of additions of moving average processing are used for pulse counting, and these are sequentially operated to perform moving average processing. This makes it possible to process the moving average in real time to reduce the apparent fluctuation of the photoelectron pulse count value and make it easier to determine the particle characteristics in the fluid, and to measure the particle size and number density of particles in real time. can.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the device of the present invention, Figure 2 is a detailed circuit diagram of the part that counts photoelectron pulses, Figure 3 is a timing chart explaining the operation, and Figure 4 is the conventional configuration. Block diagram showing ÷. 21-23... Pulse counting circuit 31-33... Latch circuit 41-43... Selection circuit 55... Comparator 56... Counter "/?
,A已-? +1iIl-,'F (Spontaneous) 1986 12JI all Special, 11 Director General 1, ・IIf+ table small 1trl+I+ 1961 Special, 81 Application No. 178827 L
;2. Title of the invention 1k No particulates in the body (,, + 71111 device 3, supplement 11 name/c f1 and (c) Usage Patent, 11 applicant name
Xing (1 old, Shikikai 14.4t JIP person
゛1 page old 03 (26B) 248
1 (I()5, Il increases by sleeve t1, 1!l
la'') Ik O6, Supplement 11, Target specification-1, weight of quotation 1, theory 11, column Drawing 7, Supplement 11: Contents 2) ``Real time CH'' on page 8, line 12, 11 3) In the figure, draw Figure 1 on the sleeve 1] as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1) A particle measuring device in a fluid that performs moving average processing on the count values of photoelectron pulses obtained from laser scattered light from particles in the fluid to determine the characteristics of the particles, comprising: a fluid in which the particles flow; a laser light source that irradiates a laser beam into the interior of the particle; a means for receiving laser scattered light from particles and converting it into an electrical signal; and a pulse generator that converts the signal from the photoelectric conversion means into a number of pulses corresponding to the intensity of the scattered light. (M+1) pulse counting circuits that count the pulses from the pulse generating means and correspond to the number of additions M in the moving average process; means for controlling the (M+1) pulse counting circuits; A comparator that compares the count value of the counting circuit with a preset setting value, and a counting circuit that counts the number of particles from the signal from the comparator, and sequentially operates the (M+1) pulse counting circuits. A particle measuring device in a fluid is characterized in that it measures particles by performing moving average processing in real time. 2) The particle measuring device in a fluid according to claim 1, wherein the means for controlling the pulse counting circuit is an (M+1)-bit shift register.