JP2013170872A - Optical particle measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether a measurement result is normal or abnormal.SOLUTION: A high interval rate is determined which indicates a ratio between a count value related to a scattering light pulse exceeding a threshold value, among scattering light pulses detected by a particle counter, and a period in which the scattering light pulse exceeds the threshold value. Based on a relation between a count value for a threshold value in the case where the threshold value is changed into a plurality of levels and at least one of the high interval rates, it is determined whether a measurement result is normal or abnormal.

Description

  The present invention relates to a measuring apparatus for counting the number of particles in an aerosol containing nanometer-size fine particles, and more particularly to an apparatus for measuring the number of aerosol particles by a CPC (Condensation Particle Counter) apparatus. The aerosol is in a state where solid or liquid fine particles are present in a relatively stable and floating state in the gas, and includes exhaust gas from automobiles, exhaust gas from factories, and the like.

  In the CPC apparatus, the droplet size is increased by condensing droplets on the particles in the aerosol with supersaturated vapor and growing them, and then the laser beam is applied to the aerosol flow in the sampling region. And the pulse signal by the laser scattered light by the particle | grains in aerosol is received and counted with photodetectors, such as a photodiode, and the number of particles is calculated | required (refer patent document 1).

  At that time, the sensitivity of the measuring apparatus may be reduced due to a decrease in the intensity of the laser beam due to contamination of the optical system for laser beam irradiation or a deterioration in the focus of the laser beam. The decrease in sensitivity leads to an error in the count value of the number of particles. In response to such a decrease in sensitivity, a photodetector such as a photodiode for laser monitoring is installed on the light incident side of the sampling area where the aerosol is irradiated with the laser beam, and the state of the laser beam before being incident on the sampling area is determined. Monitoring is done.

JP 2004-354370 A JP 2010-281788 A

J. Aerosol Sci. Vol. 21, No. 2, pp. 263-275, 1990 J. Aerosol Sci. Vol. 29, No. 5/6, pp. 601-615, 1998

  The method of indirectly monitoring laser beam deterioration (light intensity reduction, beam focus abnormality, etc.) separately from the sampling region can detect laser irradiation system abnormality to some extent. However, since monitoring is not performed in the sampling area, the state of the laser beam in the sampling area cannot be accurately grasped. An abnormality in the function of particle condensation growth leads to an error in the count value of the number of particles. However, such an abnormality in the function of particle condensation growth cannot be detected at all by a monitor of the laser irradiation system alone. For this reason, in the conventional aerosol fine particle measuring apparatus, even if the error in the measured value of the particle number concentration is large, the determination cannot be made sufficiently.

  An object of the present invention is to enable an aerosol fine particle measuring apparatus to determine whether a measurement result is normal or abnormal.

  The aerosol fine particle measuring apparatus according to the present invention includes an aerosol flow capillary for flowing a sample gas as an aerosol flow, a saturator for joining a sheath flow in a saturated vapor state with an aerosol flow flowing out of the aerosol flow capillary, and an aerosol flow from the aerosol flow capillary A cooling condenser that cools the combined gas of the saturator and the sheath flow from the saturator to grow fine particles in the aerosol flow by the steam of the sheath flow, and irradiates the aerosol flow that has passed through the cooling condenser with light. It is a CPC apparatus equipped with a particle counter that detects scattered light pulses due to particles in a flow as a measurement system.

  And as a data processing device for processing the detection signal of the particle counter, a counting means for counting the number related to the scattered light pulses exceeding the threshold among the scattered light pulses detected by the particle counter as a count number, High interval rate calculating means for calculating a ratio of a period when the scattered light pulse detected by the particle counter exceeds the threshold as a high interval rate, threshold changing means for changing the threshold, and threshold changing means And an abnormality determination means for determining whether the measurement result is normal or abnormal based on a relationship between the count number with respect to the threshold when the threshold is changed to a plurality of levels and at least one of the high interval ratios. ing.

  In this particle counter, the original count value as the detector is a count value counted by the counting means under a threshold set for normal operation, and is independent of the determination output by the abnormality determination means. Is output. The present invention determines whether the output count value is normal or abnormal.

  In order to ensure the counting in the counting means and the high interval rate in the high interval rate calculating means, the scattered light pulse detected by the particle counter is converted into a rectangular pulse signal by comparison with a threshold value. It is preferable to further include a waveform shaping circuit. In that case, the counting means counts the number related to the scattered light pulse based on the rectangular pulse signal output from the waveform shaping circuit, and the high interval rate calculating means is output from the waveform shaping circuit. The high interval rate is calculated based on the rectangular pulse signal. The threshold value changing means changes the threshold value supplied to the waveform shaping circuit.

  The counting means can count one or both of the number of rising edges and the number of falling edges of the rectangular pulse signal as a number related to the scattered light pulse.

  The counting means and the high interval rate calculating means obtain the count number and the high interval rate for each changed threshold value. A reference value for determining whether the measurement value is normal or abnormal is set in advance from one or both of the count number and the high interval rate for each threshold value. Preferably, the reference value is stored in the reference value storage unit. The abnormality determination unit compares one or both of the count number and the high interval rate with a reference value to determine whether the operation state of the apparatus is normal or abnormal.

  In a preferred embodiment, the data processing device further includes a pulse height calculating means for calculating a pulse height of the scattered light pulse detected by the particle counter. The abnormality determining means determines whether the measurement result is normal or abnormal using the pulse height calculated by the pulse height calculating means.

  By combining a classifying device (DMA (differential type electromobility measuring device) etc.) and supplying the aerosol classified and discharged by the classifying device as the sample gas of the aerosol fine particle measuring device of the present invention, The measuring device can be used as a device for measuring the particle size distribution. In such an embodiment, a charging device for charging an aerosol sample, an aerosol sample charged by the charging device in a flow of a sheath gas that does not contain an analysis target component, and charged fine particles in the sample by the electric field A classification device for classifying by diameter and taking out, and a detector for measuring the number of classified charged fine particles arranged at the take-out port of the classification device, the aerosol fine particle measuring device of the present invention as the detector. While being used, the aerosol particle measuring device is operated in synchronism with the classification operation in the classification device.

  The aerosol fine particle measuring apparatus of the present invention is a high section showing a count number related to a scattered light pulse exceeding a threshold value among scattered light pulses detected by a particle counter and a ratio of a period when the scattered light pulse exceeds the threshold value. Since the rate was calculated, it was determined whether the measurement result was normal or abnormal based on the relationship between the count number for the threshold when the threshold was changed to multiple levels and at least one of the high interval rates It is possible to determine not only an abnormality in the light amount of the light source but also an abnormality in the optical system or an abnormality in the particle growth process.

It is the schematic which shows the measurement system of the aerosol fine particle measuring device of one Example. It is a block diagram which shows the data processor which processes the particle counter and its detection signal in the Example. It is a graph which shows the relationship between a threshold value and a count number about the detection signal of an aerosol fine particle measuring device. It is a graph which shows the relationship between a threshold value and a high rate / count number about the detection signal of an aerosol particulate measuring device. It is a graph which shows the normal case and abnormal case about the detection signal of an aerosol fine particle measuring device. It is a flowchart which shows the determination operation | movement of normal and abnormality in one Example. It is a block diagram which shows the Example which used the aerosol fine particle measuring device of this invention as a detector of DMA.

  1 and 2 show an aerosol fine particle measuring apparatus according to an embodiment. As shown in FIG. 1, the measurement system is composed of a splitter 6 that separates aerosol as sample gas sucked from the sample gas flow channel 2, and an aerosol flow that uses the aerosol separated by the splitter 6 as an aerosol flow. A sheath gas flow path 8 is provided in which the remaining part of the aerosol separated by the capillary 4 and the splitter 6 is a sheath gas. The sheath gas flow path 8 is provided with a filter 10 and a variable orifice 12 downstream thereof. A saturator 14 is provided to make the sheath gas into a sheath flow in a saturated vapor state, and the sheath flow is merged with the aerosol flow flowing out from the aerosol flow capillary 4 and cooled so that the fine particles in the aerosol flow are generated by the steam of the sheath flow. A cooling condenser 16 is provided downstream of the aerosol flow capillary 4 for growth. In order to count the fine particles grown in the cooling condenser 16, a particle counter 18 is provided downstream of the cooling condenser 16. An exhaust pump 22 is provided downstream of the particle counter 18 for drawing the sample gas from the sample gas flow path 2, and a flow meter 20 is provided between the particle counter 18 and the exhaust pump 22 for adjusting the sample gas flow rate. Is provided.

  The aerosol of the sample gas sucked from the sample gas channel 2 is separated by the splitter 6, a part of which is guided to the aerosol flow capillary 4 to become an aerosol flow, and the remaining part is guided to the sheath gas channel 8 to become a sheath gas. . The reason why the sample gas flows at a large flow rate before the aerosol flow capillary 4 is to prevent the loss of fine particles due to the diffusion of the aerosol in the sample gas. In the sheath gas flow path 8, particles in the sample gas are removed by the filter 10 to become a sheath gas, and the flow rate of the sheath gas is adjusted by the variable orifice 12. The sheath gas is made into a sheath flow in a saturated vapor state by the saturator 14, merged with the aerosol flow flowing out from the aerosol flow capillary 4, and then cooled by the cooling condenser 16, whereby the fine particles in the aerosol flow are caused by the steam of the sheath flow. The particle counter 18 counts the number of particles. The flow rate of the sample gas sucked from the sample gas flow path 2 is measured by the flow meter 20, and the drive of the exhaust pump 22 is controlled so that the flow rate becomes a predetermined flow rate.

  In order to accurately measure the number of fine particles in the sample gas with such a measuring device, the flow rate of the aerosol flow flowing through the aerosol flow capillary 4 must be accurately controlled. Therefore, in this embodiment, the driving of the pump 22 is controlled so that the flow rate C of the gas passing through the flow meter 20 is constant, and the flow rate B of the sheath gas passing through the sheath gas flow path 8 is adjusted by the variable orifice 12. As a result, the flow rate A of the aerosol flow passing through the aerosol flow capillary 4 is set as (flow rate C−flow rate B).

  The flow rate A passing through the aerosol flow capillary 4 is calibrated by adjusting the variable orifice 12 so as to become a target flow rate, and the pressure loss due to the aerosol flow capillary 4 at that time is detected by the pressure gauge 24 and stored. . At the time of measurement, pressure loss due to the aerosol flow capillary 4 is detected by the pressure gauge 24, and if the value is kept at a calibrated constant value, the flow rate of the aerosol flow flowing through the aerosol flow capillary 4 is maintained at the calibrated constant value. Are treated as being.

  The flow path configuration of the aerosol fine particle measuring apparatus of the present invention is not limited to that shown in FIG. FIG. 1 to FIG. 3 of Patent Document 2 provided with another flow meter for measuring the flow rate of the sample gas flowing through the sample gas flow path 2 during calibration so that the flow rate of the aerosol flow can be directly measured and calibrated. It can also be set as the flow path structure made. An aerosol fine particle measuring apparatus having such a flow path configuration is also within the scope of the present invention.

  A particle counter 18 and a data processor for processing the detection signal are shown in FIG. In the particle counter 18, the aerosol from the cooling condenser 16 is discharged as an aerosol flow 30. The particle counter 18 includes a light source device 34 and a condenser lens 38 in order to irradiate the aerosol flow 30 with light. The light source device 34 includes, for example, a laser diode as a light source. The laser diode is automatically controlled (Auto Power Control) so that the light intensity is constant. A laser beam 36 as irradiation light from the light source device 34 is condensed at the position of the aerosol flow 30 by the condenser lens 38. When particles 32 grown by the cooling condenser 16 are present in the aerosol flow 30, scattered light 40 of the laser beam 36 is generated by the particles. In order to detect the scattered light 40, the particle counter 18 includes a condenser lens 42 and a photodetector 44. The photodetector 44 is, for example, a photodiode. The scattered light 40 is collected by a condenser lens 42 and detected by a photodiode 44.

  The flow rate of the aerosol flow 30 is adjusted so as to traverse the laser beam 36 in a state where the particles 32 in the aerosol flow 30 are not separated and are individually separated. The signal due to the scattered light 40 detected by the photodiode 44 is detected as one peak signal each time particles in the aerosol flow 30 cross the laser beam 36. This peak signal is hereinafter referred to as a scattered light pulse.

  A detection signal from the photodiode 44 is taken out as a current value, and a current-voltage conversion circuit 46 is provided to convert the current value into a voltage value. A waveform shaping circuit 48 is provided to convert the voltage value of the scattered light pulse, which is the output signal of the current-voltage conversion circuit 46, into a rectangular pulse signal by comparing with the threshold voltage.

  In order to supply a threshold voltage to the waveform shaping circuit 48, a threshold generation circuit 50 is provided. In order to make the threshold voltage generated by the threshold value generation circuit 50 variable, a threshold value changing means 52 is connected to the threshold value generation circuit 50.

  The output signal of the waveform shaping circuit 48 is a rectangular pulse signal, and a counting means 54 is provided for counting the number of counts based on the pulse signal. The counting based on the pulse signal may be performed both at the rising edge and the falling edge of the pulse signal. In this case, the count number is twice the pulse number. Further, counting based on the pulse signal may be performed at the rising edge or falling edge of the pulse signal, in which case the count number matches the pulse number.

  A ratio of a period exceeding a threshold value from the pulse signal from the waveform shaping circuit 48 is referred to as a high section ratio. In order to calculate the high interval rate from the pulse signal from the waveform shaping circuit 48, a high interval rate calculating means 56 is provided.

  Whether the measurement result is normal or abnormal based on at least one of the relationship between the threshold and the number of counts and the relationship between the threshold and the high interval rate when the threshold is changed to multiple levels by the threshold changing means 52 An abnormality determination means 58 is provided to determine whether or not

  A reference value for the abnormality determination means 58 to determine whether the measurement result is normal or abnormal is set in advance and stored in the reference value storage unit 60.

  In order to calculate the pulse height of the scattered light pulse from the current-voltage conversion circuit 46, pulse height calculation means 57 is provided.

  In the data processing device, the current-voltage conversion circuit 46, the waveform shaping circuit 48, and the threshold generation circuit 50 are configured as hardware using circuit elements. The count means 54, the high interval rate calculation means 56, and the pulse height calculation means 57 can also be realized by a hardware configuration as a count circuit, a high interval rate calculation circuit, and a pulse height calculation circuit using circuit elements, respectively.

  In this embodiment, the threshold value changing means 52, the abnormality determining means 58 and the reference value storage section 60 including the counting means 54, the high interval rate calculating means 56 and the pulse height calculating means 57 are realized by a data processing computer. . Such a data processing computer may be provided as a dedicated computer for the aerosol particle measuring apparatus, and when the aerosol particle measuring apparatus is used as a detector of another measuring apparatus, It may be realized by a control computer or a general-purpose personal computer. In FIG. 2, a portion 62 surrounded by a chain line indicates a portion realized by the computer.

  Next, the operation of this embodiment will be described. In a state where the particle count function is operating normally, the laser beam 36 is properly focused and the light scattered by the particles whose optical power maintains a predetermined value (range) is for detection. The light is focused on the photodiode 44 and detected with sufficient strength and S / N (signal to noise) ratio.

  When the beam width of the laser beam 36 is expanded due to the surface of the optical element of the laser condensing optical system becoming dirty, the high section ratio is larger than the count number of the light scattering pulses. Therefore, in one embodiment of the present invention, the abnormality of the condensing optical system is determined using the ratio of the high section ratio to the count number when the threshold value is changed to a plurality of levels.

  When the laser beam intensity in the sampling region decreases, the threshold-count number distribution shifts to the smaller threshold side. Therefore, in another embodiment of the present invention, the threshold value is varied to obtain the relationship between the threshold value and the count number, and the abnormality of the measured value is determined based on the result.

  Even if there is an abnormality in the optical system that collects the scattered light, the present invention can detect the abnormality, but this abnormality is a laser beam at a stage before the laser beam is incident on the sampling region as in the prior art. It cannot be detected by the monitoring method.

  If the function of the particle growth part due to supersaturated vapor is operating normally, even if there is a large variation in the size of the initial particles, the particles after particle growth will have a uniform particle size and light scattering. The strength also falls within a relatively narrow range of strength (see Non-Patent Documents 1 and 2). Therefore, in still another embodiment of the present invention, normality / abnormality of the function of the particle growth portion is determined from the relationship between the threshold value and the count number when the threshold value is changed to a plurality of levels.

  FIG. 3 shows the relationship between the threshold value and the count number, and FIG. 4 shows the relationship between the threshold value and the high interval rate / count number. The solid curve indicated by reference numeral 70 represents the count number in normal operation and the high interval rate / count number, and the dashed curve indicated by reference numeral 72 represents a typical count number when the particle growth portion is in a malfunction. Yes. In FIG. 3 and FIG. 4, the threshold setting value TH during normal measurement is also indicated by a thick broken line.

  The threshold value at the time of normal measurement is a threshold value when the number of fine particles in the aerosol of the sample is measured by the aerosol fine particle measuring device at the time of normal measurement. Is output as The determination result by the abnormality determination means 58 determines whether the measurement value at the normal measurement is normal or abnormal and outputs it.

  The A section of the threshold is an area where circuit noise or the like is detected and the number of particles cannot be counted normally, the B section is an area where the number of particles can be counted, and the C section is an area where there are no particles to be counted.

  In FIG. 5, the horizontal axis represents time, and the vertical axis represents a waveform when the light scattering pulse is a voltage value obtained by IV conversion (conversion from current to voltage). A solid curve 74 is for normal operation, and a dashed curve 76 is for abnormal operation. A, B, and C correspond to A, B, and C in FIGS. When the threshold value is set in the range A, there is no scattered light pulse crossing the threshold value, the count number is zero, while the high interval rate is 100%. When a threshold value is set in the area B, a scattered light pulse is detected. Assuming that the rising and falling edges when the scattered light pulse crosses the threshold value are counted, the number of counts is 2 for one scattered light pulse. When scattered light pulses are individually detected at appropriate intervals as shown in FIG. 5, the high interval rate is approximately 25%, and the aerosol flow rate is adjusted so that such a high interval rate is obtained in the region B. It is preferable to do.

  The abnormal offset 80 indicated by the abnormal waveform 76 is caused by an increase in stray light incident on the light receiving photodiode due to irregular reflection due to dirt on the lens surface. The abnormal waveform 82 is mainly caused by deterioration of the focusing of the irradiation beam. Caused by. At this time, the decrease in the wave height and the increase in the pulse width occur simultaneously, but the change in the pulse width can more reliably detect the abnormality. As the pulse width is widened, the high interval rate is larger than the count number, and the high interval rate / count number is increased. Compare this value with the reference value during normal operation to focus the irradiation beam. Can be detected.

  When the particle growth portion is in a malfunction, the pulse width does not increase, the pulse height decreases as a whole, and the relationship between the threshold value and the pulse height shifts to the smaller threshold value side. Therefore, it is possible to detect this abnormality using a range in which the number of counts does not change with respect to a change in threshold as a criterion. Since the particle size distribution after particle growth is described in Non-Patent Documents 1 and 2, normality and abnormality can be determined with reference to such distribution.

  Table 1 summarizes how the count number and the high section ratio / count number are affected when an abnormality occurs when the threshold value is changed.

  Table 1 also shows variables H_TH0, H_TH1, H_TH2, L_TH0, L_TH1, and L_TH2 for determining abnormality.

The meanings of the variables H_TH0, H_TH1, H_TH2, L_TH0, L_TH1, and L_TH2 are shown in Table 1, but are as follows.
H_TH0: Threshold value for the boundary between the high interval / the area where the count value is ∞ and the count value is zero and the count is present.
H_TH1: Average height of the counted scattered light pulse calculated from the count number distribution C (TH) for each minute range of the threshold. Here, the minute range is a unit for changing the threshold value. For example, the full scale of the pulse height is divided into about 64 steps to 256 steps, and one step is defined as a minute range.
H_TH2: Relative standard deviation (standard deviation / average value) of the pulse height distribution calculated from C (TH).
L_TH0: A threshold value that is determined to be high and the count value is zero and a boundary with a count (having the same meaning as H_TH0).
L_TH1: A threshold value between a state in which it is determined that the state is low and the count is zero and a count is present.
R_TH1: Time (seconds) / count value in the high section when the threshold is H_TH1.

  FIG. 6 is a flowchart illustrating an example of a procedure in which the abnormality determination unit 58 determines whether the measured value is normal or abnormal from the detection signal of the photodiode 44 using these variables. The values of these variables in FIG. 6 are reference values for determination, and are stored in the reference value storage means 60. The reference values shown in FIG. 6 are not exact and can vary depending on the aerosol particle measuring apparatus to be implemented. For this reason, it is appropriate to experimentally determine the reference value for the determination in the practice of the present invention.

  When the measurement is started, the detection signal from the particle counter 18 is output as a scattered light pulse represented by a voltage value by the current-voltage conversion circuit 46. The waveform shaping circuit converts the scattered light pulse into a rectangular pulse signal based on the threshold given from the threshold generation circuit 50. The counting means 54 counts the number of rising and falling edges of the rectangular pulse signal and sets the number related to the scattered light pulse as the count number. The high interval rate calculation means 56 obtains the ratio of the high interval from the rectangular pulse signal and sets it as the high interval rate. The threshold value is changed to a plurality of levels by the threshold value changing means 52, the counting means 54 calculates the count number for each threshold value, and the high section rate calculating means 56 calculates the high section ratio. The pulse height calculation means 57 calculates the pulse height of the scattered light pulse from the current-voltage conversion circuit 46.

  The abnormality determining means 58 takes in the calculation results of the counting means 54, the high interval rate calculating means 56 and the pulse height calculating means 57, calculates the variables H_TH0, H_TH1, H_TH2, L_TH0, L_TH1 and R_TH1, and the reference value storing means The reference value stored in 60 is compared. Whether the measurement value is normal or normal in the abnormality determination means 58 is determined as shown in FIG.

  First, it is determined whether or not L_TH0 is in the range of the reference value 0 to 0.1. If L_TH0 is not in the range of 0 to 0.1, it is determined that the offset level is abnormal, that is, the optical system is abnormal.

  If L_TH0 is in the range of the reference value 0 to 0.1, it is determined whether H_TH1 is in the range of the reference value 0.4 to 0.6. If H_TH1 is not in the range of the reference value 0.4 to 0.6, it is determined that the pulse height is abnormal, and it is determined that the optical system is abnormal or the particle growth is abnormal.

  If H_TH1 is in the range of the reference value 0.4 to 0.6, it is determined whether H_TH2 is within the reference value 0.15, and if H_TH2 is not within the reference value 0.15, it is determined that the particle growth is abnormal. The

  If H_TH2 is within the reference value 0.15, it is determined whether R_TH1 is in the range of 0.5 μs to 0.7 μs (microseconds). If R_TH1 is not in the range of 0.5 μs to 0.7 μs, it is determined that there is an abnormality in the optical system.

  If R_TH1 is in the range of 0.5 μs to 0.7 μs, it is determined that normal operation is being performed.

  FIG. 7 shows an embodiment in which the aerosol particle measuring apparatus of the present invention is used as a detector of a classifying apparatus.

  A differential mobility analyzer (DMA) is used as a classification device. DMA can measure the particle size of fine particles efficiently and over a wide range. A charging device 140 is provided to charge the fine particles in the sample gas and supply them from the sample supply port 111 to the DMA 102. The aerosol particle measuring apparatus 100 of one embodiment of the present invention is connected as a detector to an outlet from which particles classified by the DMA 102 are discharged.

  The DMA 102 includes an enclosure 105, a central rod 113 provided inside the enclosure 105 and having a slit 112 for taking out classified fine particles to the outside, and positively charged fine particles and negatively charged fine particles. A fine particle supply unit 104 that supplies the charged particles between the enclosure 105 and the central rod 113 is provided.

  The sheath gas passes through the filter 108, is supplied into the DMA 102, and is discharged to the outside from the discharge port 109. A sheath gas inlet 107 is provided in the upper part of the DMA 102, and a filter 108 for adjusting the flow of the sheath gas and removing impurities is attached to the lower part of the inlet 107. The sheath gas supplied from the inlet 107 flows between the enclosure 105 and the central rod 113 and is discharged to the outside by a pump or the like from the discharge port 109 provided at the lower part of the enclosure 105, and a part thereof is from the slit 112. It is designed to be taken out together with the classified fine particles.

  By applying a predetermined voltage between the enclosure 105 and the center rod 113, charged particles having a specific particle diameter enter the slit 112 of the center rod 113 and are classified. The fine particles classified and taken out through the slit 112 of the central rod 113 together with the gas component in the sample are taken out together with the sheath gas through the communication tube 115. The communication tube 115 is branched, classified, and a part of the charged particles guided together with the sheath gas is guided to the aerosol particulate measuring device 100, and the remaining part is discharged.

4 Aerosol Flow Capillary 8 Sheath Gas Channel 14 Saturator 16 Cooling Condenser 18 Particle Counter 46 Current-Voltage Conversion Circuit 48 Waveform Shaping Circuit 50 Threshold Generation Circuit 52 Threshold Changing Unit 54 Counting Unit 56 High Interval Rate Calculation Unit 57 Pulse Height Calculation means 58 Abnormality determination means 60 Reference value storage section

Claims (5)

An aerosol flow capillary for flowing the sample gas as an aerosol flow;
A saturator for joining a sheath flow in a saturated vapor state with an aerosol flow flowing out of the aerosol flow capillary;
A cooling condenser that cools the combined gas of the aerosol flow from the aerosol flow capillary and the sheath flow from the saturator, and grows fine particles in the aerosol flow by the steam of the sheath flow;
A particle counter that irradiates the aerosol flow that has passed through the cooling condenser with light, and detects a scattered light pulse by particles in the aerosol flow;
Counting means for counting the number of scattered light pulses detected by the particle counter that are related to the scattered light pulses that exceed a threshold as a count number;
A high interval rate calculating means for calculating, as a high interval rate, a ratio of a period in which the scattered light pulse detected by the particle counter exceeds the threshold;
Threshold changing means for changing the threshold;
An abnormality that determines whether the measurement result is normal or abnormal based on the relationship between the count number with respect to the threshold value and at least one of the high interval rates when the threshold value is changed to a plurality of levels by the threshold value changing unit A determination means;
Aerosol particulate measuring device equipped with. A waveform shaping circuit that converts the scattered light pulse detected by the particle counter into a rectangular pulse signal by comparison with a threshold;
The counting means counts the number related to the scattered light pulse based on the rectangular pulse signal output from the waveform shaping circuit,
The high interval rate calculating means calculates the high interval rate based on a rectangular pulse signal output from the waveform shaping circuit,
The aerosol fine particle measuring apparatus according to claim 1, wherein the threshold changing unit changes a threshold supplied to the waveform shaping circuit.   3. The aerosol particle measuring apparatus according to claim 2, wherein the counting means counts one or both of the number of rising edges and the number of falling edges of the rectangular pulse signal as a number related to the scattered light pulse. A pulse height calculating means for calculating the pulse height of the scattered light pulse detected by the particle counter;
The aerosol according to any one of claims 1 to 3, wherein the abnormality determination unit determines whether the measurement result is normal or abnormal using the pulse height calculated by the pulse height calculation unit. Fine particle measuring device. A charging device for charging the aerosol sample;
A classifying device for supplying an aerosol sample charged by the charging device in a flow of a sheath gas not containing an analysis target component, and classifying charged fine particles in the sample for each particle diameter by an electric field; and
A detector for measuring the number of classified charged fine particles arranged at the outlet of the classifier;
With
5. The aerosol fine particle measuring apparatus according to claim 1, wherein the aerosol fine particle measuring apparatus is operated in synchronization with a classification operation in the classification apparatus. Measuring device.

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