JPS61173133A - Particle analyzing instrument - Google Patents

Abstract

PURPOSE:To improve the analyzing accuracy of a particle analyzing instrument with a simple circuit by differentiating the output from a means for generating quantity of electricity according to the passage of a particle in a fine hole and processing the waveform thereof with a waveform processing unit including a discriminating means, prescribed threshold varying means, etc. CONSTITUTION:A conduction type particle detector 7 is formed of a vessel 1 contg. a particle suspended sample 2, an insulating wall 4 having the fine hole 3, electrodes 5, 6 and a detecting part which generates a pulse. The output thereof is inputted to a differentiating circuit 31 and a phase transfer correcting circuit 39 and is processed by the waveform processing unit 8 which comprises the discriminating means consisting of leading edge and trailing edge comparators 33, 34 and a TM center pulse circuit 42, the prescribed threshold varying means consisting of an ACL circuit 32, a zero level detecting means consisting of a zero cross comparator 35, a sample holding circuit 40 and a crest value A/D conversion circuit 41. A grain size recorder 9 is then operated. The distortion of the particle signal in the stage of passage through the fine hole 3 is thus corrected and the analyzing accuracy is improved.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a particle analyzer that is applied to a conductive particle detection device that uses power.

[Conventional technology]

A conductive particle detection device uses a pair of electrodes immersed in a suspension of measurement particles suspended in a thin electrolyte solution with a salt concentration of about 0.8%, and an insulating wall with micropores between the two electrodes. The structure is such that a potential difference is applied between both electrodes so that current flows between the electrodes only through the pores. In other words, when a water pressure difference is applied between the liquid on both sides and the particles flow together with the liquid through the pores, if the pore size is chosen appropriately for the particle size, a current change proportional to the particle volume will occur between the electrodes in response to the passage of the particles. This is a device that takes advantage of the characteristics that occur in A detailed examination of the particle detection waveform reveals that only when the particle passes near the center of the pore, the pulse peak value is proportional to the particle volume, while the waveform that passes near the periphery of the pore shows a partially high pulse peak value. This has been confirmed to cause errors in particle size information. 1E71'fi's sea bream view 111. 'Rokumu + Su candy ￥19;
As shown in the schematic diagram of Figure 8 and the waveform diagram of Figure 8, the current line density around the entrance of the pore 11 is high and the sensitivity is high. However, the figure is a collective representation;
Generally, the suspension is diluted to such an extent that each condition occurs separately. A is a case where the particles 12 pass very close to the inner peripheral surface of the pore 11, and the wave height value is high at the entrance and exit, and the wave height value is almost flat between them. When the mouth passes near the center of the pore 11, two particles 12 may be present at the same time, and the waveform has two peaks, with a relatively deep peak between them. It is a valley. 3 shows a case where the particle 12 passes exactly through the center of the pore 11, and shows a neat mountain-shaped waveform with a symmetrical peak at one point. The second case is when the wave passes obliquely near the inner circumferential surface of the pore 11 at the entrance and near the center at the exit, and the waveform has a high crest part at the entrance and a flat part following this. It becomes. The conductive particle detection device has a simple structure and high sensitivity, so it eliminates the problem of pore clogging when scanning a suspension.
Although it has the drawback of particle signal distortion due to the particle passage path, it is one of the widely used particle measurement devices. In the field of precision particle analysis, countermeasures against the detection distortion of this device have long been an issue, and various studies have been conducted. ``Hydrodynamic focusing'' or ``sheath flow'' is a technique that uses Bernoulli's principle to narrow down the pore flow path of particles to a narrow area in the center.
One such method is an improved method in terms of fluid dynamics, which is found in Japanese Patent No. 3-119086 and others. Another improvement method is to analyze the detected particle signal waveform and select a waveform that ignores all distorted signals other than undistorted signals passing near the center of the pore. There are many others, but these two are representative.

[Problems to be solved by the invention]

Although the fluid device that restricts the flow described above is ideal, it requires a complicated fluid mechanism, making the device expensive and difficult to maintain. As a discriminating circuit for waveform selection, for example, Japanese Patent Publication No. 54-2
Some of these are disclosed in Japanese Patent Publication No. 6919 and Japanese Patent Publication No. 12980/1983. In each of these, the voltage obtained by peak-holding the particle waveform is divided into predetermined proportions, each pressure level is set as a threshold voltage, and each threshold voltage is compared with the delayed particle waveform. Waveforms are selected by relatively measuring the waveform duration at the level using an integrating circuit and comparing it with a normal reference value. However, since the number of signals ignored by this waveform selection increases considerably, it is necessary to increase the number of samplings to maintain accuracy, which leaves problems in terms of efficiency and accuracy. Patent Application No. 55-115331 (Issued on June 4, 1981)
The patent application N) is filed by the same applicant, and the invention particle analyzer of this application improves the above-mentioned problem. 1% I, friso (Mu Soe no cho ヱ 4 址彷authored by A L 10 lead) - Condition setting was difficult, analysis precision was not high enough, and the circuit was complicated. An object of the present invention is to provide a particle analyzer with a simpler circuit configuration and higher analysis accuracy.

[Means for Solving the Problems] The technical means (structure of the invention) taken by this invention to solve the above problems are as follows. That is, the particle analyzer of the present invention includes a means for generating an amount of electricity accompanying the passage of particles through a pore, a means for differentiating the amount of electricity generated, and an output waveform of the differentiating means that is positive near zero level,
a discriminator that generates a pulse when the pulse is outside a predetermined threshold between both negative levels; a predetermined threshold variable means that changes the predetermined threshold to a greater or lesser extent in accordance with a larger or smaller change in the input signal; and an output waveform of the differentiator. 0 level detection means for detecting a point in time when is at 0 level; signal level holding means for holding the signal level of the amount of generated electricity according to the output signal of the discrimination means and the output signal of the θ level detection means; and the discrimination means and A/D conversion means for A/D converting the output signal of the signal level holding means using the output signal of the signal level holding means. [Operation] The effect of the configuration of the present invention will become clear from the explanation of the operation in the following embodiments.

【Example】

An embodiment of the present invention will be described based on FIGS. 1 to 3. FIG. 1 shows a block diagram of a waveform processing device which is the main part of a particle analyzer, FIG. 2 shows waveforms of each part showing its operation, and FIG. 3 is a conceptual diagram of the overall configuration of the particle analyzer. In FIG. 3, the conductive particle detection device 7 includes a sample container 1
1 particle suspension sample 2. Detector (insulating wall) 4 with pores 3
and electrodes 5 and 6, and includes a fluid control section that flows and quantifies the sample 2, and a detection section that applies a potential difference to the electrodes 5 and 6 to generate and amplify detection pulses. The waveform processing device 8 forms the main part of this invention,
Figure 1 shows the block diagram of the wavematic C
oparater Level 1 circuit) 321 Leading edge comparator 33. Trailing edge comparator 34. Zero cross comparator 35. AND circuit 36. One shot throat circuit 3
7. Conversion start pulse circuit 38° phase shift correction circuit 39. The sample and hold circuit 40 consists of a peak value A/D conversion circuit 41 and a Tm center pulse circuit 42. a is an input terminal line that is input from the conductive particle detection device 7 to the differentiation circuit 31 and the phase shift correction circuit 39. The differentiating circuit 31 is an example of the "differentiating means" in the configuration of the invention. Leading edge comparator 33. Trailing edge comparator 34 and T
The m center pulse circuit 42 is an example of the "discriminating means" referred to in the configuration of the invention. The zero cross comparator 35
This is an example of "level detection means". The ACL circuit 32 is an example of the "predetermined threshold variable means" in the configuration of the invention. The sample hold circuit 40 is an example of the "signal level hold means" in the configuration of the invention. The peak value A/D conversion circuit 41 is the “A/D converter circuit 41” that
This is an example of "D conversion means". The output terminal of the differentiating circuit 31 is connected to the leading edge comparator 33, &
Edge comparator 34 and zero cross comparator 35
is connected to the input terminal of A Tm center pulse circuit 42 is connected between the output terminals of the leading edge comparator 33 and the trailing edge comparator 34, and the output terminal of the Tm center pulse circuit 42 and the output terminal of the zero cross comparator 35 are connected to the input terminal of the AND circuit 36. There is. The output terminal of the AND circuit 36 is connected to the input terminal of the one-shot circuit 37, and the output terminal of the one-shot circuit 37 is connected to the trigger terminal of the sample-and-hold circuit 40. The one-shot circuit 37 generates a trigger pulse for the sample-and-hold circuit 40. The output terminal of the phase shift correction circuit 39 is connected to the sample hole L+t
J & i ＾＾1 Iso 7I Mala Dokdo Mu and 1 +-+l −
The output terminal of the LLD circuit 40 is the peak value A/D conversion circuit 41
is connected to the input terminal of Sample hold circuit 4
The output terminal of 0 is connected to the input terminal of the peak value A/D conversion circuit 41. When triggered by the output of the one-shot circuit 37, the sample-hold circuit 40 outputs the signal to the peak value A/D conversion circuit 41. The peak value A/D conversion circuit 41 outputs the signal to the grain size recording device 9 shown in FIG. The output terminal of the trailing edge comparator 34 is connected to the input terminal of the conversion start pulse circuit 38, and the output terminal of the conversion start pulse circuit 38 is connected to the trigger terminal of the peak value A/D conversion circuit 41. The trigger pulse generated by the conversion start pulse circuit 38 has a peak value of A
/D conversion circuit 41. Next, the operation of the waveform processing device 8 will be explained based on FIG. 2. ■''Particle pulses of various waveforms amplified from the conductive particle detection device 7 are differentiated via the input terminal line a. The waveforms are illustrated in fal in Figure 2. That is, the waveforms corresponding to ``A'', ``A'', and ``C'' in Figure 7 are shown in this order. This is a circuit for obtaining a signal proportional to the rate of change, and the output corresponding to the slope coefficient value of the input waveform (a) in Figure 2 is obtained on the signal line, and the differential waveform (b) is obtained. ■ ACL circuit 32 is a circuit that supplies comparison voltages for the leading edge comparator 33 and the trailing edge comparator 34, and the comparison voltage changes from large to small according to large and small changes in the input signal. Note that when there is no signal, A bias DC voltage is supplied. ■ The output voltage of the ACL circuit 32 is applied as a positive voltage to the leading edge comparator 33 (see E1 in FIG. 2), whereas the trailing edge comparator 34 is supplied with a bias DC voltage. is inverted and a negative voltage is applied (see E2 in Figure 2), and the output of the differentiating circuit 31 is similarly applied. At the same time, the output pulse trailing edge comparator 34 generates an output pulse when the output waveform of the differentiating circuit 31 exceeds the level voltage to the negative side (see FIG. 2 (dl)). It generates a pulse that rises at the fall of the output of the trailing edge comparator 34 and falls at the rise of the output of the trailing edge comparator 34 (see Figure 2 (el)). If the Tm center pulse circuit 42 is exceeded, an output pulse is generated (see Fig. 2 (f)). ■ When the output of the zero cross comparator 35 and the output of the Tm center pulse circuit 42 are input to the AND circuit 36,
The AND circuit 36 outputs a pulse to the one-shot circuit 37 (see FIG. 2(g)). (2) This pulse causes the one-shot circuit 37 to output a hold start trigger signal to the trigger terminal of the sample and hold circuit 40 (see FIG. 2(h)). ■ The sample and hold circuit 40 holds the input signal from the phase shift correction circuit 39 at that point by manually inputting the hold start trigger signal (see Fig. 2 fj))
. [Phase] On the other hand, the output of the trailing edge comparator 34 is input to the conversion start pulse circuit 38, and the conversion start pulse circuit 38 converts the conversion start pulse into the peak value A/D conversion circuit 4 by the rising edge of the trailing edge pulse.
1 (see Figure 2 (1)). ■ The wave height value A/D conversion circuit 4 converts the signal wave height held in ■ to A by the conversion start pulse.
/D conversion and output to the particle size recording device 9. Next, when comparing the voltage of the differential signal with a comparator,
We will investigate ways to obtain stable pulse output without being affected by waveform distortion or signal level fluctuations. FIG. 4 shows the characteristics of the leading edge pulse and the trailing edge pulse. The left side of the figure shows a normal waveform, and the right side shows an abnormal waveform. (A) is the input waveform, (B
) is a differential waveform, and when a blood cell signal is differentiated, the distorted part is emphasized. Therefore, if the comparator voltage is set to be constant as shown in Figure (B), the pulse width will not only be applied to the distorted portion but also fluctuate depending on the magnitude of the input signal. 'In order to solve these two problems, the following two methods can be considered. +l) Automatically pick up the half width of the differential signal. (2) Move the comparison voltage of the comparator according to the input level. The circuit shown in FIG. 5 adopts the method (2). In FIG. 5, 33 is a leading edge comparator, C1 is a capacitor, R1, R2, and R3 are resistors, and vo is a DC power supply. The capacitor C1 and the resistor R1 constitute a differentiating circuit 31. 32a is the positive side portion of the ACL circuit 32. When there is no signal, a comparison voltage V is applied to the input terminal of the leading edge comparator 33. is applied. The input signal is asf-ml>,
/ (Q 1 book Q-) 1:' Miyako Rokukou A lacquer spinning pressure V. is added to 1. Applied to the (-) input terminal of leading edge comparator 33. At this time, the differential signal shown in the diagram (C'), which is differentiated by the time constant of cl and R1, is applied to the (+) input terminal.
The comparator comparison voltage is synchronized with the input signal (dashed line). The waveforms of this circuit are shown in FIG. (A) is the input waveform, (
B) is a differential waveform, and the broken line indicates the comparator voltage. (C
) is the comparator output waveform. The characteristics of this circuit are that it is less susceptible to the influence of the intermediate portion of the differential waveform, and that the comparison voltage also changes in a manner that follows changes in the signal level, so that fluctuations in pulse width can be suppressed. With the above configuration, the influence of low-level distortion in the intermediate portion of the output of the differentiating circuit 31 is transmitted to the zero-cross comparator 35.
The influence on the leading edge comparator 33 and the trailing edge comparator 34 is suppressed, the accuracy of particle analysis is improved, and the circuit configuration is simplified compared to the invention disclosed in Japanese Patent Application No. 115331/1982. Further, the reliability of the output of the trailing edge pulse increases, and it becomes possible to actually use it as a conversion start pulse, and it becomes possible to sample and hold pulses other than the normal pulse level. Therefore, more simple logic can be used, the circuit configuration can be further simplified, and accuracy can be improved. Therefore, it is possible to obtain an accurate particle size distribution signal by simply adding a processing circuit to a conventional detection mechanism without using a sheath mechanism.

【Effect of the invention】

According to this invention, compared to the one disclosed in Japanese Patent Application No. 59-115331, it is possible to simplify the circuit configuration and further improve the accuracy of analysis.

[Brief explanation of drawings]

Fig. 1 shows a block diagram of a waveform processing device which is the main part of a particle analyzer according to an embodiment of the present invention, Fig. 2 shows waveforms of each part showing its operation, and Fig. 3 shows the overall configuration of the particle analyzer. Figure 4 is a characteristic diagram showing the characteristics of leading edge pulses and trailing edge pulses, Figure 5 is a circuit diagram around the leading edge comparator circuit, Figure 6 is an improved characteristic diagram, and Figure 7 is a conventional characteristic diagram. A sectional view of the main part of the example, and FIG. 8 is a waveform diagram thereof. 31... Differentiation circuit (differentiation means), 32... ACL circuit (predetermined threshold variable means), 33... Leading edge comparator,
34... Trailing edge comparator, 42... Tm center pulse circuit, (33, 34, 42)... Discrimination means, 3
5...Zero cross comparator (0 level detection means)
, 40... Sample hold circuit (signal level hold means), 41... Peak value A/D conversion circuit (A/D conversion means) Fig. 1 Fig. 2 Fig. 5

Claims (1)

[Claims] means for generating an amount of electricity accompanying the passage of particles through the pores, means for differentiating the generated amount of electricity, and generating a pulse when the output waveform of the differentiating means is outside a predetermined threshold between positive and negative levels near 0 level. a discrimination means, and the predetermined threshold is determined by the magnitude of the input signal.
a predetermined threshold variable means that changes large or small in response to small changes;
level detection means, and signal level holding means for holding the signal level of the generated quantity of electricity based on the output signal of the discrimination means and the output signal of the 0 level detection means;
A/D conversion means for A/D converting the output signal of the signal level holding means based on the output signal of the discrimination means.