JPH0147733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for classifying and counting particles such as red blood cells and platelets based on the size of these particles. It is an object of the present invention to provide a particle classification and counting device that can accurately and effectively count particles.

Conventionally, particles such as red blood cells and platelets suspended in physiological saline etc. are detected based on the optical or electrical difference between the liquid and the particles and converted into an electrical pulse signal, and the size of the signal is determined by the particle size. Since it is proportional to the size of the blood, an appropriate threshold circuit is provided to classify and count the blood into two types: platelets, red blood cells, and red blood cells. There are two methods for this counting: In both cases, the large particles are red blood cells and the small particles are platelets.

(1) A method of subtracting the red blood cell count from the red blood cell and platelet count results.

(2) A method of directly counting platelets by detecting the arrival of a red blood cell signal and sending an inhibition signal to the platelet counting circuit to prevent pulses caused by red blood cells from being counted.

Among the above methods, method (2) matches the rise time of the red blood cell signal across two levels,
In addition, it is necessary to either make it independent of the falling time or to detect the peak point and issue an inhibition signal. If a red blood cell signal that rises relatively slowly comes, malfunctions may occur, or subtle signals may occur. There were drawbacks such as the need for adjustment for accurate time matching. On the other hand, method (1) involves counting separately and then subtracting, and the circuit configuration is relatively simple. However, on the other hand, with simple subtraction, for example, two red blood cells are detected in succession. In the case of double-peak signal waveforms that occur in cases such as cases, even if there is one pulse signal in the platelet region, it is counted as two pulses at the red blood cell level, and as a result of subtraction, the number of platelets decreases and errors occur. There were some shortcomings. Furthermore, both methods have the disadvantage that noise is superimposed on the red blood cell signal or the platelet signal, resulting in sharp pulses near the threshold when the pulse rises or falls, resulting in erroneous counting.

The present invention has been made in order to solve the above-mentioned drawbacks, and it is possible to use a mixture of two types of large and small particles, such as red blood cells and platelets, suspended in a liquid by electrical or optical differences between the particles and the suspended liquid. A particle detection device that detects based on the particle size and generates a signal proportional to the size of the particle, and a particle detection device that is connected to this particle detection device and differentiates the detected waveform and detects the rise and fall of the signal based on the differentiated signal. A large particle time constant switching signal generation circuit that generates a gate signal from an edge and a trailing edge of a falling edge, and a circuit that is connected to the large particle time constant switching signal generation circuit and the particle detection device and allows a detection signal to pass through using the gate signal. a large particle variable time constant circuit that stabilizes the baseline by changing the time constant of the small particle/large particle time constant switching signal generation circuit connected to the particle detection device via an amplifier; The large particle time constant switching signal generation circuit and variable time constant circuit for large particles are connected to the amplifier, and the detection signal for large particles is connected to the variable time constant circuit for large particles and the baseline is stabilized. A large particle threshold circuit is connected to a small particle/large particle variable time constant circuit to pass the detection signals for small particles and large particles whose baseline is stabilized.
A large particle threshold circuit, a timing pulse generation circuit connected to the small particle/large particle time constant switching signal generation circuit, and a discrimination circuit connected to the large particle threshold circuit, the small particle/large particle threshold circuit, and the timing pulse generation circuit. By configuring a particle classification and counting device with a large particle counting circuit and a small particle counting circuit connected to this discrimination circuit, it is possible to measure two types of particles, large and small, especially the smaller one, with high precision. The purpose is to provide a particle classification and counting device that can

Hereinafter, the configuration of the present invention will be explained based on the drawings. FIG. 1 is an explanatory diagram showing one embodiment of the configuration of the apparatus of the present invention, and FIG. 2 is a signal waveform diagram of each part.
1 is a particle detection device that detects particles and generates a pulse signal based on the electrical or optical difference between particles such as platelets and red blood cells and the liquid in which the particles are suspended. A device is used that detects the particles based on the difference in electrical impedance between the particles and the liquid by passing the particles through channels (micropores) formed in the gap, and generates a signal proportional to the size of the particles. 2 is a large particle time constant switching signal generation circuit which differentiates the detected waveform, detects the rising and falling edges of the signal based on the differentiated signal, and generates a gate signal from the leading edge of the rising edge and the trailing edge of the falling edge; 3, this circuit; A variable time constant circuit for large particles that stabilizes the baseline by changing the time constant of the circuit that allows the detection signal to pass through using a gate signal, 4 is a large particle threshold circuit, 5 is an amplifier, and 6 is a time constant switch for small and large particles. Signal generation circuit, 7 is a variable time constant circuit for small particles/large particles, 8 is a small particle/large particle threshold circuit, 9 is a timing pulse generation circuit, 1
0 is a discrimination circuit, 11 is a large particle counting circuit, and 12 is a small particle counting circuit.

In FIG. 2, the left side shows a signal system for large particles such as red blood cells, and the right side shows a signal system for small particles such as platelets. The output signal a of the particle detection device 1 is amplified by the amplifier 5 as shown by a', and the signal due to large particles is saturated. When the two signals a and a' are simply compared, it is clear that there are two signals due to large particles in a, but only one can be determined in the case of a'. Therefore, when the large particles of a are subtracted from (large particles + small particles) of a', an error occurs in that the number of small particles is redundantly subtracted. On the other hand, if one large particle signal is included in the signal a, small particles will be counted correctly, but an error will occur for large particles. Therefore, the present invention provides an apparatus that simultaneously detects large particles and small particles and accurately determines each particle.

Before explaining the operating principle of the device of the present invention, a variable time constant circuit for stabilizing the detection signal will be explained. FIG. 3 is an explanatory diagram showing an example of a variable time constant circuit, and FIG. 4 is an example of input waveforms and output waveforms. In the particle detection signal, phenomena such as fluctuations in the baseline occur due to noise signals other than particles, relatively slow signals due to bubbles, and the like. This fluctuation in the baseline is superimposed on the particle signal, increasing the apparent size of the signal and causing a phenomenon as if a large particle had been detected. In order to prevent this, a method is used in which the time constant of the circuit is made small except when the particle signal is being input, and then returned to the normal circuit time constant when the particle signal is being input.
The reason why the circuit is not completely cut off is to prevent impulse-like noise from occurring when the cut-off state returns to the normal state. In Fig. 3, numeral 13 is a time constant switching circuit using CR (capacitor and resistor), which can vary the signal passband by the time constant determined by capacitor _C1 and resistor _R1 or _R2 . , the switching signal is the output signal of the differentiating circuit 14 and the two comparators 15,
16 is used to detect the positive and negative parts of the differential signal, that is, the rising and falling parts of the particle signal, the RS flip-flop 17 generates a gate signal, and the time constant switching circuit 13 is switched only during that period. A method is used to return the time constant to . Capacitor C ₁ of time constant switching circuit 13
The time constants switched by R ₁ and R ₂ are on the order of several milliseconds and on the order of 1 microsecond or less, and since the pulse width of the particle signal is on the order of several microseconds to several tens of microseconds, At a time constant of milliseconds, the waveform of the original signal can pass through without being damaged; on the other hand, at a time constant of 1 microsecond or less, excess signals due to bubbles and the like can be sufficiently removed. Note that the time constant of the differentiating circuit 14 is on the order of 1 microsecond. In FIG. 4, A is a signal before passing through the variable time constant circuit, and B is a signal after passing through the variable time constant circuit. It can be seen that the baseline is stabilized and at the same time unnecessary signals are removed.

Now, in the signal waveform diagram of Fig. 2, a and
The differential signals of a' become b and b'. The detection signals of the rising edges of the signals a and a' are c ₁ and c' ₂ , and the detection signals of the falling edges of the signals a and a' are c ₂ and c' ₂ . As described above, this can be obtained by setting a predetermined threshold value for the differential signal using the two comparators 15, 16, etc., and turning on the comparator when the predetermined threshold value is exceeded. Furthermore, by the RS flip-flop 17,
Time constant switching signals d and d' are obtained. The output signals of the time constant switching signal generation circuits 2 and 6 obtained as described above are sent to the variable time constant circuits 3 and 7.
It produces an output signal consisting only of particle signals, such as e'.

Further, in the apparatus of the present invention, as shown in FIG. 5 as an example, a signal compression circuit 18 is provided subsequent to the differentiation circuit 14 in order to remove noise caused by differentiation of the signal. The example shown in Figure 5 is a push-pull circuit used in power amplifier circuits, etc., but by adjusting the bias, it is possible to make an output only at a predetermined voltage or higher at the rise of the signal, as shown in Figure 6. ing. That is, due to the small noise signal superimposed on the base line of the differential signal, the comparators 15 and 1
The voltage at the center is compressed to eliminate noise so that 6 is not accidentally triggered. For example, as shown in Figure 7, the input signal is a sine curve signal (7
(upper side of the figure), the output becomes a compressed waveform signal (lower side of Figure 7). Next, an example of an actual signal waveform is shown in FIG. The upper part of Figure 8 is the differential circuit 1.
By passing the output waveform of No. 4 through the signal compression circuit 18, a clean signal from which noise has been removed can be obtained as shown in the lower part of FIG. The above operation is performed by forcibly generating distortion using a circuit for eliminating crossover distortion of the push-pull circuit.

The stable baseline signals e and e' obtained by the variable time constant circuits 3 and 7 are applied to predetermined threshold voltages Vl and Vs.
By passing the signal through the threshold voltage circuits 4 and 8 having the respective threshold voltages, only signals exceeding the respective threshold voltages are passed, and signals f and f' are obtained. Since the noise signal superimposed on the signals e and e' has not yet been removed, whisker-like noise occurs in f and f'.
In comparing f and f', it is easy to distinguish between large particles and whisker-like noise, but on the other hand, in the case of small particles, it is not always clear to distinguish them from noise. However, it is easy to distinguish between large particles and noise, and by simply passing the particles through a simple filter circuit built into the discrimination circuit 10, a signal like signal g from which whisker-like noise has been removed can be obtained. This is counted by a large particle counting circuit 11. On the other hand, signals caused by small particles are not always wide pulses as shown in the signal waveform diagram in Figure 2, and may be difficult to distinguish from whisker-like noise. will be processed. For this process,
A part of the signal from the time constant switching signal generation circuit 6 is used. First, in the timing pulse generation circuit 9, the signal from the small particle system time constant switching signal generation circuit 6 is
c' ₁ and c' ₂ are inverted and become h ₁ and h ₂ . The h ₂ signal is delayed and becomes the h′ ₂ signal. A timing signal called i is generated from the falling edge of the h ₁ pulse and the rising edge of the h' ₂ pulse, and is sent to the discrimination circuit 10 . That is, this timing signal i becomes a narrower pulse than the above-mentioned time constant switching signal d'. On the other hand, the output signal of the small particle/large particle threshold circuit 8
By inverting f', a signal k is obtained, and by ANDing it with the timing signal i, a mixed signal m of large particles and small particles is obtained. Furthermore, since the above-mentioned signal g representing only large particles has a high threshold level, the bimodal mountain of large particles is separated into two and counted as two particles, and therefore the mixed signal If we simply subtract from m, an error will occur due to extra subtraction. Therefore, the following processing is performed.

The inverted signal k of the signal f' is a mixed signal of large particles and small particles, and when this is differentiated, a signal l is obtained. If we operate an RS flip-flop using both signal g and signal l, which is triggered by the falling edge of signal g and reset by signal l,
A signal n is obtained. By ANDing this signal n and the timing signal i, a signal p corresponding to a large particle is obtained. Therefore, the signal p and the signal m can be subtracted in real time, and a signal of only small particles can be obtained. This signal is counted by a small particle counting circuit 12.

As explained above, although the procedure of the apparatus of the present invention is somewhat complicated, it is possible to perform highly accurate classification counting by reliably operating each part of the circuit. Particularly in blood cell counters used in fields such as blood testing, even if a solution in which blood cells are dispersed fairly uniformly is used, when counting each blood cell particle one by one, the interval at which particles are detected is limited. are not always constant, and are usually detected very close together like a Poisson distribution, or detected at wide intervals, making it extremely difficult to process. In particular, when particles are detected close together, they may approach several microns even if the average particle interval is 100 μs. Furthermore, when large particles are detected continuously, so-called bimodal detection pulses occur. Therefore, by adopting the above method, more reliable classification and counting becomes possible.

The device of the present invention incorporates the following circuit in order to operate more reliably even when very close pulses occur. That is, in the circuit 6 that generates the time constant switching signal, rising detection signals c ₁ , c′ ₁ and falling detection signals c 2 , c′ 1 obtained from the differential signals b and b′ of the detection signal a or a _′ are generated.
RS flip-flop 1 shown in FIG. 3 by c′ ₂
7 to obtain switching signals d and d', but the 9th
In the case of an approach signal caused by a small particle, such as a'' shown in the figure, the pulse interval is extremely short, so the rising detection signal c'' ₁ and the falling detection signal c'' ₂ obtained from the differential signal b'' are also very close to each other. As a result, a problem arises in that the RS flip-flop 17 does not operate correctly. That is, since there is almost no time between the trailing edge 20 of the falling detection pulse c'' ₂ caused by the first small particle and the leading edge 21 of the rising detection pulse c'' ₁ of the next pulse, the RS flip-flop
A phenomenon occurs in which the next action after one action does not work. Such malfunctions are a big problem when using normal pulse circuits in very special fields such as counting the number of platelets and red blood cells. The reliability of the system is reduced.

In order to solve the above problems, in the apparatus of the present invention, the rising edge detection signal _c''1 is intentionally oscillated like the signal _c3 shown in FIG. 9 to ensure reliable operation. Specifically, as shown in Fig. 10, when a pulse is input to an oscillation circuit 19 using a Schmitt trigger circuit or the like, the oscillation continues for only that period.In other words, the signal generated by the initial particle is The trailing edge 20 of the falling detection pulse is followed by the leading edge 21 of the rising detection pulse of the next particle's signal, and the RS flip-flop is reset even if it cannot subsequently go to the set state. Since the detection signal _c''1 of the rising edge of the particle pulse, which is a signal, is oscillated to bring it into the state _c3 , the set signals come one after another and the RS flip-flop is reliably set. After that, the trailing edge 22 of the detection signal of the fall of the particle signal
to return to the reset state again. The switching signal d'' obtained in the above manner is generated in such a way that it operates reliably even if the particle signals occur very close to each other, so that two particles will not be mistakenly counted as one. , only one circuit is allowed to oscillate and the other circuit is left untouched, resulting in a more accurate operation in the second circuit.In the above method, it is not very desirable to have both circuits oscillate. It is not impossible that the last pulse does not overlap with the rising edge of another circuit's oscillation pulse, and even if the input voltage is completely cut off due to stray capacitance in the circuit, some residual voltage may still exist. It is quite conceivable that the oscillation circuit is located at the input end of the oscillation circuit and promotes the continuation of oscillation.

As explained above, the particle classification and counting device of the present invention does not have a simple gate circuit in its circuit configuration, but differentiates a signal, generates a gate signal using an RS flip-flop based on the differentiated signal, and generates a gate signal based on the gate signal. The baseline is stabilized by changing the time constant with a variable time constant circuit, and the signal used in the process of creating the gate signal can be used as a timing signal for discrimination between large particles and small particles, making it possible to perform subtraction in real time, and also to eliminate differential noise. In order to remove this, crossover distortion is intentionally used to compress the waveform, and in order to ensure that the RS flip-flop that generates the gate signal operates reliably, the set signal of the circuit is intentionally oscillated. Because pulses of large particles and small particles are output in real time, there is no need for calculation processing after counting, and since waveform processing or calculation processing is performed using the same timing pulse, there are many It does not require complicated time adjustment using delay circuits, etc., and also uses an oscillation circuit during waveform processing to ensure operation, resulting in extremely high accuracy of measured values. .

[Brief explanation of drawings]

Fig. 1 is a systematic explanatory diagram showing one embodiment of the device of the present invention, Fig. 2 is a signal waveform diagram of each part, Fig. 3 is an explanatory diagram showing an example of a variable time constant circuit, and Fig. 4 is an input waveform. and a waveform diagram showing an example of the output waveform, fifth
The figure is an explanatory diagram showing another example around the differential circuit, No. 6
The figure shows an example of the output waveform obtained by the circuit shown in Fig. 5, and Fig. 7 shows an example of the waveform input to the circuit shown in Fig. 5, and an example of the waveform output from the circuit shown in Fig. 5. Figure 8 shows an example of the actual output waveform of the differentiating circuit shown in Figure 5 and the waveform actually obtained by passing the signal through the signal compression circuit shown in Figure 5. FIG. 10 is a waveform diagram for explaining the operation of the oscillation circuit shown in FIG. 10. FIG. 10 is an explanatory diagram showing an example of the oscillation circuit. DESCRIPTION OF SYMBOLS 1...Particle detection device, 2...Large particle time constant switching signal generation circuit, 3...Large particle variable time constant circuit, 4...Large particle threshold circuit, 5...Amplifier, 6...
...Time constant switching signal generation circuit for small particles and large particles, 7
...Variable time constant circuit for small particles/large particles, 8...Small particle/large particle threshold circuit, 9...Timing pulse generation circuit, 10...Discrimination circuit, 11...Large particle counting circuit, 12...Small Particle counting circuit, 13... Time constant switching circuit, 14... Differentiation circuit, 15, 16...
Comparator, 17...RS flip-flop,
18... Signal compression circuit, 19... Oscillation circuit, 20
...Pulse trailing edge, 21...Pulse leading edge, 22...
Trailing edge of the pulse.

Claims (1)

[Scope of Claims] 1. A method for detecting a mixture of two types of large and small particles, such as red blood cells and platelets, suspended in a liquid based on electrical or optical differences between the particles and the suspended liquid, and determining the size of the particles. a particle detection device that generates a signal proportional to;
A time constant switching signal generation circuit for large particles that is connected to this particle detection device and differentiates the detected waveform, detects the rising and falling edges of the signal based on the differentiated signal, and issues gate signals from the leading edge of the rising edge and the trailing edge of the falling edge. and a large particle variable time constant circuit that is connected to the large particle time constant switching signal generation circuit and the particle detection device and that stabilizes the baseline by changing the time constant of the circuit that allows the detection signal to pass using the gate signal. A time constant switching signal generation circuit for small particles and large particles connected to the particle detection device via an amplifier, and a time constant switching signal generation circuit for small particles and large particles connected to the time constant switching signal generation circuit for small particles and large particles and the amplifier. A variable time constant circuit, a large particle threshold circuit that is connected to the variable time constant circuit for large particles and passes a detection signal related to the stabilized large particles, and a large particle threshold circuit that is connected to the variable time constant circuit for small and large particles and that stabilizes the baseline The detection signal for small particles and large particles is stabilized.
A large particle threshold circuit, a timing pulse generation circuit connected to the small particle/large particle time constant switching signal generation circuit, and a discrimination circuit connected to the large particle threshold circuit, the small particle/large particle threshold circuit, and the timing pulse generation circuit. A particle classification and counting device comprising: a circuit; and a large particle counting circuit and a small particle counting circuit connected to the discrimination circuit. 2. The particle classification and counting device according to claim 1, wherein the time constant switching signal generation circuit includes a signal compression circuit that compresses the differential signal to reduce noise. 3. The particle classification and counting device according to claim 1, wherein the time constant switching signal generation circuit includes an oscillation circuit for oscillating a set signal of the RS flip-flop to ensure operation.