JP2008102037A - Charged particle amount evaluation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle amount evaluation system capable of evaluating the amount of charged particles with high precision even under an environment easy to dew-condensate. <P>SOLUTION: The charged particle amount evaluation system 1 is equipped with a concentric cylindrical electrode 2 constituted so that a columnar inside conductor 2a and a cylindrical outside conductor 2b having a diameter larger than that of the columnar inside conductor 2a are concentrically arranged, a suction fan 3 for producing a laminar flow in the space between both conductors 2a and 2b along the axial direction of the concentric cylindrical electrode 2, a voltage source 5 for applying voltage across both conductors 2a and 2b, an ammeter 4 for measuring the current flowing across both conductors 2a and 2b, a current value acquiring part 12 for acquiring the measuring value of the ammeter 4, a dewing detection part 16 for detecting the presence of the dewing occurring on both conductors 2a and 2b which form the wall surface of the flow channel of the laminar flow and a particle size calculation part 15 for evaluating the amount of the charged particles on the basis of the shape and dimension of the concentric cylindrical electrode 2, the flow rate of the laminar flow due to the suction fan 3, the applied voltage of the voltage source 5 and the current value acquired by the current value acquiring part 12 in a case that no dewing is detected by the dewing detection part 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charged particle amount evaluation apparatus for evaluating the particle size, the number of particles, and the like of fine particles floating in the atmosphere.

  This kind of charged particle quantity evaluation apparatus is a differential type electric mobility measuring device (DMA: Differential) that measures the particle size of fine particles by utilizing the difference in the moving speed (electric mobility) of charged fine particles in an electric field. Mobility Analyzer) has been conventionally provided (see, for example, Patent Document 1).

  However, since the charged particle amount evaluation apparatus using DMA is large, a charged particle amount evaluation apparatus using a double concentric cylinder called a Gel Dien capacitor has been conventionally provided (for example, see Non-Patent Document 1). FIG. 5 is a schematic configuration diagram of a charged particle amount evaluation apparatus 1 using a gel diene capacitor. The charged particle amount evaluation apparatus 1 includes a concentric cylindrical electrode 2, an intake fan 3, an ammeter 4, a voltage source. 5 as a main configuration.

  The concentric cylindrical electrode 2 is configured by concentrically arranging cylindrical inner conductors 2a and outer conductors 2b having different radii. In the double concentric cylinder, a DC voltage is applied to the outer conductor 2b by the voltage source 5, and the inner conductor 2a is grounded. The voltage source 5 can change the power supply voltage by a voltage control unit (not shown).

  The intake fan 3 sucks air through the space between the inner conductor 2a and the outer conductor 2b, thereby causing air to flow in the direction of the arrow A through the space between the inner conductor 2a and the outer conductor 2b. A laminar flow with uniform flow direction and velocity is generated.

  The ammeter 4 measures the current flowing between the inner conductor 2a and the outer conductor 2b, and the number of charged particles can be calculated from the current value.

  In this apparatus, when air is sucked by the intake fan 3, the inner conductor 2a is grounded, and a voltage V is applied to the outer conductor 2b by the voltage source 5 to give a potential difference between the inner and outer conductors. Charged particles in the air sucked between the conductors are attracted to the inner conductor 2a by an electric field generated between the two conductors. When the charged particles flow into the inner conductor 2a, a current is generated between the two conductors, so that the number of charged particles can be measured based on the measured value of the ammeter 4. In addition, if the polarity of the voltage V applied by the voltage source 5 and the polarity of the measured value of the ammeter 4 are taken into account, charged particles having either positive or negative polarity can be measured.

Here, the particle size of the charged particles depends on the mobility, and the mobility is determined by making the size of the double cylinder (inner conductor 2a and outer conductor 2b) and the air flow rate constant, the applied voltage of the voltage source 5. Determined by V. Therefore, by changing the applied voltage of the voltage source 5 and measuring the current value with the ammeter 4, the number of charged particles having a predetermined particle diameter can be obtained. However, in the measuring apparatus of FIG. 5 using a double concentric cylinder called a gel diene capacitor, all charged particles having a mobility equal to or higher than the mobility determined by the applied voltage of the voltage source 5 (particle size or less) are taken and the total number is evaluated. ing.
Japanese Patent Laid-Open No. 10-288600 Edited by Shinichiro Kitagawa, “Atmospheric Electricals”, Tokai University Press, June 10, 1996, pp. 47-49

  In the charged particle amount evaluation apparatus 1 described above, the distribution of the number of particles is obtained by measuring the particle amount of the charged particles in a predetermined particle size range based on the change in mobility. When dew condensation occurs between the inner conductor 2a and the outer conductor 2b forming the wall surface, there is a problem that an error occurs in the measurement result.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a charged particle amount evaluation apparatus that can accurately evaluate the amount of charged particles even in an environment where condensation is likely to occur. It is in.

  In order to achieve the above object, a first aspect of the present invention provides a concentric cylindrical electrode configured by concentrically arranging a cylindrical inner conductor and a cylindrical outer conductor having a diameter larger than that of the inner conductor, and an inner conductor. An air flow generating means for generating a laminar flow in the axial direction of the concentric cylindrical electrode in a space between the inner conductor and the outer conductor, a voltage applying means for applying a voltage between the inner conductor and the outer conductor, and the inner conductor and the outer conductor A current measuring means for measuring the current flowing between the inner conductor and the outer conductor, a dew condensation detecting means for detecting the presence or absence of dew condensation occurring on the inner and outer conductors forming the wall surface of the laminar flow path, and no dew condensation by the dew condensation detecting means. When detected, the charged particle amount is evaluated based on the shape and size of the concentric cylindrical electrode, the laminar flow rate by the air flow generating unit, the applied voltage by the voltage applying unit, and the measurement result of the current measuring unit. With evaluation means Characterized in that was.

  According to a second aspect of the present invention, in the first aspect of the present invention, the air is heated in the middle of the laminar flow path and downstream of the concentric cylindrical electrode in the air flow generation direction when evaluating the charged particle amount. A heater for heating, air blowing direction switching means for switching the direction of air flow generation by the air flow generating means, and when the condensation detection means detects condensation, the heater is used to heat the air and the air flow generation means using the air blowing direction switching means There is provided a warming-up operation control means for performing a warming-up operation for switching the airflow generation direction by the direction opposite to that at the time of evaluation of the charged particle amount.

  According to a third aspect of the present invention, in the second aspect of the present invention, the warm-up operation control means continues the warm-up operation until the condensation detection means detects no condensation.

  According to a fourth aspect of the present invention, in the second or third aspect of the present invention, there is provided an air flow control means for changing the air flow rate of the air flow generating means, and the warm air operation control means uses the air flow control means for a predetermined time during the warm air operation. The air flow generation means is configured to increase the air flow rate to a predetermined flow rate larger than the air flow rate at the time of evaluating the charged particle amount.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the dew condensation detection means is the amount of charge stored in the concentric cylindrical electrode obtained from the measurement result of the current measurement means and the voltage applied by the voltage application means. Capacitance obtained from the above and the capacitance obtained from the shape and dimensions of concentric cylindrical electrodes are compared, and the occurrence of condensation is detected because the absolute value of the difference between the two exceeds a predetermined threshold. It is characterized by.

  According to the first aspect of the present invention, the charged particle amount evaluating means evaluates the charged particle amount when the condensation detecting means detects that there is no condensation, and in a condensation environment where errors are likely to occur, the charged particles Since the amount is not evaluated, there is an effect that the charged particle amount can be evaluated with high accuracy.

  According to the second aspect of the present invention, when the dew condensation detecting means detects that there is dew condensation, the warm-up operation control means heats the air with the heater, and the air flow generating means determines the blowing direction when the charged particle amount is evaluated. Since the air heated by the heater is blown into the space between the inner conductor and the outer conductor, the condensation of the inner and outer conductors forming the wall surface of the laminar flow path is prevented. Can be removed. Further, when condensation is no longer detected as a result of the warm-up operation, the charged particle amount is evaluated by the charged particle amount evaluating means, so that the charged particle amount can be evaluated with higher accuracy.

  According to the invention of claim 3, since the warm-up operation control means continues the warm-up operation until the condensation detection means detects no condensation, the warm-up operation is completed in the shortest time necessary to remove the condensation. Thus, it is possible to return to a state where the charged particle amount can be evaluated.

  According to the invention of claim 4, since the warm-up operation control means increases the air flow rate of the air flow generating means to a predetermined flow rate larger than the air flow rate at the time of evaluating the charged particle amount for a predetermined time during the warm-up operation. In addition to removing condensation, it is possible to blow off dust and dirt adhering to the inner conductor and the outer conductor, and the charged particle amount can be evaluated with higher accuracy.

  According to the fifth aspect of the present invention, the dew condensation detection means includes a capacitance obtained from the amount of charge stored in the concentric cylindrical electrode obtained from the measurement result of the current measurement means and a voltage applied by the voltage application means, and a concentric cylindrical shape. Since the absolute value of the difference from the capacitance determined from the electrode shape and dimensions exceeds a predetermined threshold, the occurrence of condensation is detected, so there is no need to provide a separate sensor for detecting condensation. There is an effect that the presence or absence of condensation can be detected at low cost.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, a charged particle amount evaluation apparatus 1 according to the present embodiment includes a concentric cylindrical electrode 2, an intake fan 3 serving as an air flow generating unit, an ammeter 4 serving as a current measuring unit, and a voltage source serving as a voltage applying unit. 5 and the controller 10 are provided as main components.

  The concentric cylindrical electrode 2 is configured by concentrically arranging a columnar inner conductor 2a and a cylindrical outer conductor 2b having a diameter larger than that of the inner conductor 2a. The inner conductor 2a and the outer conductor 2b are preferably formed of a material having high conductivity so that the charged particles can be easily attracted and the current flowing between the two conductors can be easily measured. It is formed.

  The inner conductor 2 a is not hollow, and has a ground terminal 21 and a current measurement terminal 22 on the peripheral surface, and is grounded to the ground via a ground line 25 connected to the ground terminal 21. The inner conductor 2a is held in the outer conductor 2b via a holding member (not shown) having a high insulating property in order to prevent an error from occurring due to charging and current flowing. As a material for the member, it is preferable to use, for example, a highly insulating ethylene trifluoride chloride resin.

  The outer conductor 2 b has a hollow cylindrical shape and includes a power connection terminal 23 and a current measurement terminal 24, and a DC voltage from the voltage source 5 is applied through the power connection terminal 23. An ammeter 4 is connected between the current measurement terminal 22 of the inner conductor 2a and the current measurement terminal 24 of the outer conductor 2b. Here, the ground terminal 21 of the inner conductor 2a and the power connection terminal 23 of the outer conductor 2b constitute a voltage application terminal, and the DC voltage of the voltage source 5 is applied between the two conductors 2a and 2b.

  Here, the relationship between the particle size and mobility of the charged particles, the applied voltage applied between the outer conductor 2b and the inner conductor 2a, and the shape and dimensions of the concentric cylindrical electrode 2 will be described with reference to FIG.

  Assuming that the charged particles in the air have the same mobility, the charged particles flowing from the point P at the edge of the outer conductor 2b on the intake side of the concentric cylindrical electrode 2 receive the electric field between the conductors 2a and 2b. Assuming that the particles are captured at the point S, all the charged particles flowing into the cylinder of the concentric cylindrical electrode 2 are captured by the inner conductor 2a. The position of the point S where the charged particles are captured changes by adjusting the voltage applied to the outer conductor 2b and the flow rate of the airflow.

  By the way, charged particles having various mobilities exist in the actual air, and flow from the point P under a certain applied voltage and flow rate, and at the edge T on the outlet side of the inner conductor 2a. The mobility of charged particles to be trapped is called critical mobility. This critical mobility indicates a boundary between charged particles that can be captured by the inner conductor 2a and charged particles that cannot be captured by the inner conductor 2a, and all charged particles having a mobility higher than the critical mobility are captured by the inner conductor 2a. However, a part of the charged particles whose mobility is lower than the critical mobility is not captured and flows out from the outlet of the concentric cylindrical electrode 2 to the outside.

  For example, if the charged particles flowing from the point R in FIG. 5 are captured at the point T, the charged particles having the same mobility and charged from the region between the concentric circle C1 passing through the point R and the outer conductor 2b. The particles flow out from the outlet of the concentric cylindrical electrode 2, and only the charged particles flowing in from the region between the concentric circle C1 and the inner conductor 2a (the hatched portion in the figure) are captured by the inner conductor 2a. .

  Here, the critical mobility kc of the charged particles is such that the applied voltage to the outer conductor 2b is V, the laminar flow rate between the inner conductor 2a and the outer conductor 2b is φ, the radius of the outer conductor 2b is r0, the inner When the radius of the conductor 2a is r1 and the total length in the axial direction of the concentric cylindrical electrode 2 is L, the following expression (1) is used.

  Further, the relationship between the mobility kc and the particle size Dp of the charged particles is expressed by the following formula when the charged number of the charged particles is np, the elementary charge is e, the Cunningham correction coefficient is Cc, and the viscosity coefficient of air is μ: 2).

  Here, the Cunningham correction coefficient Cc is a function of the particle diameter Dp, and the critical mobility kc, the particle diameter Dp, and the applied voltage V can be obtained by simultaneous equations (1) and (2). When determining the relationship between the particle size Dp and the applied voltage V, the Cunningham correction coefficient Cc varies depending on the particle size Dp, and therefore, the critical mobility kc is eliminated by simultaneous equations (1) and (2). Calculate numerically from the formula.

By the way, in the present embodiment, the following description will be made assuming that the measurement range of the particle size is, for example, 0.6 to 28 nm. Here, assuming that the charged particle number np is 1, the electric mobility is 5.49 to 0.00274 cm ² / V · s from the equation (2). The laminar flow rate φ is 0.05 m ³ / min (50 L / min), the radius r 1 of the inner conductor 2 a is 4.5 cm, the radius r 0 of the outer conductor 2 b is 4.8 cm, and the total length of the concentric cylindrical electrode 2 Is fixed at 52 cm, the applied voltage V is 0 to 60V.

  Further, the intake fan 3 is disposed on the air flow outlet side (right side in FIG. 1) with respect to the concentric cylindrical electrode 2 in the air flow generation direction at the time of evaluation of the charged particle amount, and between the inner conductor 2a and the outer conductor 2b. By sucking the air in the annular space 2c, an airflow flowing along the axial direction of the concentric cylindrical electrode 2 is generated in the annular space 2c. The rotational speed of the intake fan 3 is kept constant, and the flow rate of the airflow is kept constant. Further, in order to generate a laminar flow in the space between the two conductors 2a and 2b (annular space 2c), the diameter of the rotary blade (not shown) provided in the intake fan 3 is formed larger than the diameter of the outer conductor 2b. The rotary fan has a rotation surface orthogonal to the direction of the central axis of the concentric cylindrical electrode 2, and the intake fan so that the rotation axis of the rotary blade and the central axis of the concentric cylindrical electrode 2 exist on the same straight line. 3 is arranged and connected between the concentric cylindrical electrode 2 and the intake fan 3 so as not to have irregularities that disturb the flow of airflow. The laminar flow is generated in the space between the two conductors 2a and 2b because the charged particles flowing into the space between the two conductors 2a and 2b from the inlet side (left side in FIG. 1) of the concentric cylindrical electrode 2 are generated. This is because the electric field is applied by moving the charged particles at a constant speed by advancing parallel to the axial direction of the concentric cylindrical electrode 2.

  The ammeter 4 is a digital ammeter connected between the current measurement terminal 22 of the inner conductor 2a and the current measurement terminal 24 of the outer conductor 2b. The measured value of the current is measured by a current value acquisition unit 12 described later. Obtained automatically. The number of charged particles can be obtained from the current flowing between the inner conductor 2a and the outer conductor 2b. If the current flowing between the two conductors 2a and 2b is is assumed, the charged number np of the charged particles is assumed to be 1. Therefore, the number ns of charged particles is expressed by the following formula (3). When the charge number np is not 1, it can be calculated by multiplying the electric quantity e in the equation (3) by the charge number np. Here, e is the elementary electric charge, and φ is the airflow rate.

  The voltage source 5 is a variable power source that applies a DC voltage to the outer conductor 2b via the power connection terminal 23, and the applied voltage is automatically controlled by a voltage control unit 11 described later so that measurement can be performed by automatic control. Is done. The polarity of the voltage applied by the voltage source 5 can be switched between positive and negative. If the voltage applied by the voltage source 5 is positive, positive charged particles can be measured, and the applied voltage is negative. If so, negatively charged particles can be measured.

  Next, the configuration of the controller 10 will be described. The controller 10 includes a voltage control unit 11, a current value acquisition unit 12, an input unit 13, and an arithmetic processing unit 14 as main components.

  The voltage controller 11 automatically controls the applied voltage of the voltage source 5 based on the voltage value and polarity of the applied voltage input from the particle size calculator 15 described later.

  The current value acquisition unit 12 automatically acquires a current measurement value from the ammeter 4 and outputs the acquired current value to a particle size calculation unit 15 and a dew condensation detection unit 16 (condensation detection unit) described later.

  The input unit 13 is for the user to input measurement conditions such as the measurement range of the charged particles to be measured, the sweep width of the polarity and the particle size, the flow rate, and the dimensions of the concentric cylindrical electrode 2. The measurement conditions are output to the particle size calculation unit 15 and the dew condensation detection unit 16 of the arithmetic processing unit 14.

  The arithmetic processing unit 14 includes a particle size calculation unit 15 (charged particle amount evaluation unit) and a dew condensation detection unit 16, and sets an applied voltage of the voltage source 5 using the voltage control unit 11 or a current value acquisition unit 12. The particle size distribution of the charged particles is obtained based on the current value obtained from the above, or when the dew condensation detection unit 16 detects dew condensation on the inner electrode 2a or the outer electrode 2b, a dew condensation detection signal is sent to the particle size calculation unit 15. It has a function to output. The arithmetic processing unit 14 is configured using, for example, a microcomputer, and the particle size calculation unit 15 and the dew condensation detection unit 16 are realized by a calculation function of the microcomputer.

  The particle size calculation unit 15 calculates the voltage applied to the outer conductor 2b from the relationship between the particle size of the charged particles to be measured and the mobility in accordance with the measurement conditions input from the input unit 13, and calculates the calculation result as a voltage control unit. 11 and the condensation detection unit 16, and the number of charged particles having a particle size equal to or smaller than the particle size set by the applied voltage of the voltage source 5 is calculated based on the current value acquired from the current value acquisition unit 12. In the particle size calculation unit 15, the voltage applied by the voltage source 5 is swept using the voltage control unit 11 to change the particle size of the measurement target by a predetermined sweep width, and the particle size of the measurement target is changed to the sweep width. By measuring the number of particles every time it is changed, the particle size distribution of the number of charged particles can be obtained. Further, the particle size calculator 15 outputs the polarity of the charged particles to be measured to the voltage controller 11. The particle size calculator 15 stores the measured particle size distribution as electronic data in a storage unit (not shown) and outputs the particle size distribution to an output device (printer, monitor device, etc.) not shown. Further, the particle size calculation unit 15 has a function of stopping the evaluation of the charged particle amount while a detection signal is input when a detection signal of condensation is input from the condensation detection unit 16 described later.

  The dew condensation detection unit 16 includes a capacitance C1 obtained from the shape and dimensions of the concentric cylindrical electrode 2 and a charge amount and voltage source stored in the concentric cylindrical electrode 2 obtained from the current value obtained by the current value obtaining unit 12. The occurrence of condensation is detected by comparing the capacitance C2 obtained from the applied voltage 5. That is, the dew condensation detection unit 16 uses the following equation (4) based on the measurement conditions (dimensions of the concentric cylindrical electrode 2) input from the input unit 13, and the electrostatic capacitance C1 of the concentric cylindrical electrode 2: Ask for. Where ε is the dielectric constant of air.

  This capacitance C1 is a unique value determined by the shape and dimensions of the concentric cylindrical electrode 2.

  On the other hand, the dew condensation detection unit 16 obtains the capacitance C2 from the current value is input from the current value acquisition unit 12, the time t, and the applied voltage V using the following equation (5).

  The dew condensation detection unit 16 then determines the actual capacitance C2 obtained from the capacitance C1 inherent to the concentric cylindrical electrode 2 determined by the shape and dimensions of the concentric cylindrical electrode 2, the current value is, and the applied voltage V. If the two values are different (that is, if the absolute value of the difference between the capacitances C1 and C2 exceeds a predetermined threshold value), a dew condensation detection signal indicating the occurrence of dew condensation is sent to the particle size calculation unit 15 It outputs.

  Next, the operation of the charged particle amount evaluation apparatus 1 of the present embodiment will be described with reference to the flowchart of FIG.

  First, the controller 10 is turned on. When power is supplied to the controller 10 and the controller 10 starts to operate, the person in charge of measurement uses the input unit 13 to measure the range and polarity of the particle size of the charged particles, the sweep width of the particle size, and the concentric cylindrical electrode. Measurement conditions such as the dimension 2 are input (step S1).

  Next, the power source of the voltage source 5 is turned on. However, when the power is turned on, the voltage of the voltage source 5 is set to zero. The power source of the voltage source 5 may be turned on in conjunction with the power source of the controller 10.

  When the power source of the voltage source 5 is turned on, the particle size calculation unit 15 detects the particle size measurement range and polarity of the charged particles input using the input unit 13, the flow rate of the charged particles, and the concentric cylindrical electrode 2. The applied voltage corresponding to the particle size range to be measured can be solved by simultaneously solving the relational expressions (1) and (2) of the particle size, critical mobility and applied voltage based on the measurement conditions such as the dimensions of The range of fluctuations and the sweep width of the applied voltage corresponding to the sweep width of the particle size are calculated, and when changing the particle size from the minimum value to the maximum value with a predetermined sweep width, the application corresponding to each particle size The voltage is obtained (step S2).

  Next, the particle size calculation unit 15 outputs the voltage value and polarity of the applied voltage corresponding to the minimum value of the particle size to the voltage control unit 11 and the dew condensation detection unit 16 (step S3). Under the current measurement conditions, the minimum value of the particle size is 0.6 nm. At this time, the voltage control unit 11 sets the applied voltage of the voltage source 5, and the applied voltage corresponding to the minimum value of the particle size is applied to the outer conductor 2b (step S4). Note that the polarity of the voltage applied to the outer conductor 2b is the same as the polarity of the charged particles to be measured. When negatively charged particles are to be measured, the polarity of the voltage applied to the outer conductor 2b is negative. As a result, an electric field is generated from the inner conductor 2a to the outer conductor 2b, and negatively charged particles are attracted to the inner conductor 2a grounded to the ground by the electric field. Then, charged particles having a particle size equal to or smaller than the particle size set by the voltage applied by the voltage source 5 are taken into the inner conductor 2a, and a current flows between the inner conductor 2a and the outer conductor 2b (step S5).

  When a current flows through the charged particles taken into the inner conductor 2a, the current value is measured by the ammeter 4. The measurement value of the ammeter 4 is automatically acquired by the current value acquisition unit 12, and the current value acquisition unit 12 outputs the acquired current value to the particle size calculation unit 15 and the dew condensation detection unit 16 (step S6).

  The dew condensation detection unit 16 calculates the capacitance C1 inherent to the concentric cylindrical electrode 2 from the measurement conditions input using the input unit 13 using the equation (4), and stores it in a storage unit (not shown) ( Step S7). The process of step S7 for calculating the capacitance C1 need only be performed once every time measurement conditions are input using the input unit 13, and thereafter, the value of the capacitance C1 is read from the storage unit. good.

  Also, the dew condensation detection unit 16 uses the above equation (5) from the applied voltage V input from the particle size calculation unit 15, the current value is acquired from the current value acquisition unit 12, and the acquired time t. The actual capacitance C2 is calculated and stored in the storage unit (step S8), and the presence or absence of condensation is determined by comparison with the specific capacitance C1 obtained in step S7 (step S9). That is, the dew condensation detection unit 16 determines whether or not the intrinsic capacitance C1 obtained from the shape and size of the concentric cylindrical electrode 2 and the actual capacitance C2 match, and if they do not match. (In other words, when the absolute value of the difference between the capacitances C1 and C2 exceeds a predetermined threshold value), it is determined that condensation has occurred, and a condensation detection signal is output to the particle size calculator 15 (step S10). Thereafter, the dew condensation detection signal is continuously output to the particle size calculator 15 until dew condensation is no longer detected.

  Here, when the dew condensation detection signal is input from the dew condensation detection unit 16, the particle size calculation unit 15 immediately stops the evaluation of the charged particle amount (step S11), and the above-described step S6 until the dew condensation detection signal is not input. The process of S9 is repeatedly executed. On the other hand, when the dew condensation detection signal is not input from the dew condensation detection unit 16, the particle size calculation unit 15 uses the current value is input from the current value acquisition unit 12 and uses the above equation (3) to obtain the minimum particle size or less. The number of charged particles is calculated, and the particle size and number of charged particles to be measured are stored in the storage unit (step S12).

  When the particle size and number of charged particles to be measured are stored in the storage unit, the particle size calculation unit 15 determines whether or not the measurement has been completed for all measurement ranges (step S13), and the measurement must be completed. For example, after outputting the voltage value and polarity of the applied voltage when the particle size is increased by a predetermined sweep width to the voltage control unit 11 and the dew condensation detection unit 16 (step S14), the processing of the above steps S4 to S12 is performed. repeat. In the present embodiment, the sweep width is 0.2 nm in the particle size range of 0.6 to 2 nm, and the sweep width is 2 nm in the particle size range of 2 to 28 nm. The voltage value of the applied voltage when the particle size is 0.8 nm is output.

  In this device, the number of particles is calculated by repeating the above-described processing S4 to S13 at each particle size setting value every time the particle size is swept by a predetermined sweep width from 0.6 nm to 28 nm. Then, the particle size distribution (number distribution with respect to the particle size) is obtained, and in step S13, when the particle size calculation unit 15 determines that the measurement has been completed in the entire measurement range, the calculation result of the particle size distribution is obtained. While memorize | storing in a memory | storage part, a measurement result is output to an output device (step S15).

  As described above, in the charged particle amount evaluation apparatus 1 of the present embodiment, the dew condensation detection unit 16 that detects the presence or absence of dew condensation on the inner conductor 2a and the outer conductor 2b forming the wall surface of the laminar flow channel in the concentric cylindrical electrode 2. The particle size calculation unit 15 evaluates the charged particle amount when the condensation detection unit 16 determines that there is no condensation, and the charged particle amount is evaluated in a condensation environment where measurement errors are likely to occur. Since it is not performed, the charged particle amount can be evaluated with high accuracy.

  Further, in the dew condensation detection unit 16, the charge amount and voltage stored in the concentric cylindrical electrode 2 obtained from the electrostatic capacity C <b> 1 obtained from the shape and size of the concentric cylindrical electrode 2 and the current value obtained by the current value obtaining unit 12. Compared with the capacitance C2 obtained from the applied voltage of the source 5, and since the absolute value of the difference between the capacitances C1 and C2 exceeds a predetermined threshold value, it is determined that condensation has occurred. There is no need to separately provide a sensor for detecting condensation, and the presence or absence of condensation can be detected at low cost.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS.

  In the present embodiment, in the charged particle amount evaluation apparatus 1 described in the first embodiment, the charging is performed in the middle of the voltage source 6 for supplying power to the intake fan 3 and the laminar flow path generated by the intake fan 3. Airflow generation of the intake fan 3 by reversing the polarity of the voltage applied by the heater 7 which is arranged downstream of the concentric cylindrical electrode 2 in the airflow generation direction at the time of particle amount evaluation and heats the air and the voltage source 6 When the airflow control unit 17 (air blowing direction switching unit) that switches the direction and the dew condensation detection unit 16 detects the occurrence of dew condensation, the heater 7 heats the air in the vicinity of the intake fan 3 and the air flow control unit 17 There is provided a warming-up operation control unit 18 that performs a warming-up operation that switches the direction of airflow generation by the intake fan 3 to the direction opposite to that during the evaluation of the charged particle amount. The configuration other than the voltage source 6, the heater 7, the airflow control unit 17, and the warming-up operation control unit 18 is the same as that in the first embodiment, and therefore, common constituent elements are denoted by the same reference numerals and description thereof is omitted. To do.

  The voltage source 6 is a variable power source that applies a DC voltage to the intake fan 3 via a voltage terminal 31, and the polarity of the applied voltage is switched between positive and negative by the airflow control unit 17. For example, when the airflow control unit 17 sets the polarity of the voltage applied by the voltage source 6 to a positive voltage, the intake fan 3 sucks air from the concentric cylindrical electrode 2 side, and the air flows to the right side in FIG. Air is blown, and the direction of airflow generation is the direction of arrow A. On the other hand, when the airflow control unit 17 sets the polarity of the voltage applied by the voltage source 6 to a negative voltage, the intake fan 3 draws air from the heater 7 side, and the air flows to the left side in FIG. 3 via the concentric cylindrical electrode 2. The air flow generation direction is the direction of arrow B.

  The heater 7 heats the air in the vicinity of the intake fan 3 (in this embodiment, the exhaust side in the direction of airflow generation when the charged particle amount is evaluated), and a power-on signal from the warm-up operation control unit 18 is connected to the connection terminal 71. When the signal is input to the switch, the built-in switch is turned on, and power is supplied from a voltage source (not shown) to generate heat.

  The input unit 13 is for inputting the warm-up operation time in addition to the measurement conditions described in the first embodiment, and has a function of outputting the input warm-up operation time to the warm-up operation control unit 18.

  In addition to the function described in the first embodiment, the particle size calculation unit 15 starts measuring the amount of charged particles when the dew condensation detection signal is not input after the dew condensation detection signal is input from the dew condensation detection unit 16. It has a function.

  The dew condensation detection unit 16 is the same as that described in the first embodiment. When the dew condensation is detected, a dew condensation detection signal is output to the particle size calculation unit 15 and the warm-up operation control unit 18. In the first embodiment, the dew condensation detection unit 16 outputs a dew condensation detection signal only while detecting the occurrence of dew condensation. In the present embodiment, the dew condensation detection unit 16 generates the dew condensation. Is detected and the dew condensation detection signal is output, the dew condensation detection signal continues to be output until the warm air end signal indicating the end of the warm air operation is input from the warm air operation control unit 18, and when the warm air end signal is input. If dew condensation is not detected again, the dew condensation detection signal output is stopped.

  The airflow control unit 17 switches the polarity of the voltage applied to the voltage source 6 in accordance with the polarity of the polarity switching signal input from the warm-up operation control unit 18, and reverses the forward / reverse direction of the airflow generation direction by the intake fan 3. ing.

  When the dew condensation detection signal is input from the dew condensation detection unit 16, the warm air operation control unit 18 outputs a polarity switching signal to the air flow control unit 17 to start the warm air operation, and the direction of air flow generation by the intake fan 3. Is switched to the opposite direction to that during the evaluation of the charged particle amount, and a function for outputting a power-on signal to the heater 7 is provided. During the warming-up operation, air dried by heating by the heater 7 is sucked into the intake fan 3 and blown into the annular space 2c of the concentric cylindrical electrode 2, so that the inner conductor 2a and the outer conductor 2b are warmed to cause dew condensation. Can be removed. The warming-up operation control unit 18 holds the warming-up operation time input using the input unit 13 in a storage unit (not shown), and after the dew condensation detection signal is input until the warming-up operation time continues. When the warm-up operation is performed and the warm-up operation time elapses, a polarity switching signal is output to the air flow control unit 17 to reverse the air flow generation direction to the direction when the charged particle amount is evaluated, and the power supply is supplied to the connection terminal 71 of the heater 7. After stopping the power supply to the heater 7 by outputting a stop signal, a warm-up end signal is output to the dew condensation detection unit 16. Here, the warm-up operation time is set to a time slightly longer than the time required to remove the condensation of the inner conductor 2a and the outer conductor 2b, and the warm-up operation is continued for the warm-up operation time, whereby the inner conductor 2a. And the dew condensation of the outer conductor 2b can be reliably eliminated.

  Next, the operation of the charged particle amount evaluation apparatus 1 of this embodiment will be described with reference to the flowchart of FIG.

  First, the controller 10 is turned on. When electric power is supplied to the controller 10 and the controller 10 starts operating, the person in charge of measurement uses the input unit 13 to measure the particle diameter measurement range and polarity, the sweep width of the particle diameter, and the concentric cylindrical electrode 2. Measurement conditions such as dimensions and warm-up operation time are input (step S1).

  Next, the power source of the voltage source 6 is turned on. However, the voltage value of the voltage source 6 when the power is turned on is a preset value, and a laminar flow having a known flow rate is generated by the intake fan 3. The power source of the voltage source 6 may be turned on in conjunction with the power source of the controller 10.

  Thereafter, the power source of the voltage source 5 is turned on. However, when the power is turned on, the voltage of the voltage source 5 is set to zero. The power source of the voltage source 5 may be turned on in conjunction with the power source of the controller 10.

  When the power source of the voltage source 5 is turned on, the particle size calculation unit 15 detects the particle size measurement range and polarity of the charged particles input using the input unit 13, the flow rate of the charged particles, and the concentric cylindrical electrode 2. The applied voltage corresponding to the particle size range to be measured can be solved by simultaneously solving the relational expressions (1) and (2) of the particle size, critical mobility and applied voltage based on the measurement conditions such as the dimensions of The range of fluctuations and the sweep width of the applied voltage corresponding to the sweep width of the particle size are calculated, and when changing the particle size from the minimum value to the maximum value with a predetermined sweep width, the application corresponding to each particle size The voltage is obtained (step S2).

  Next, the particle size calculation unit 15 outputs the voltage value and polarity of the applied voltage corresponding to the minimum value of the particle size to the voltage control unit 11 and the dew condensation detection unit 16 (step S3). Under the current measurement conditions, the minimum value of the particle size is 0.6 nm. At this time, the voltage control unit 11 sets the applied voltage of the voltage source 5, and the applied voltage corresponding to the minimum value of the particle size is applied to the outer conductor 2b (step S4). Note that the polarity of the voltage applied to the outer conductor 2b is the same as the polarity of the charged particles to be measured. When negatively charged particles are to be measured, the polarity of the voltage applied to the outer conductor 2b is negative. As a result, an electric field is generated from the inner conductor 2a to the outer conductor 2b, and negatively charged particles are attracted to the inner conductor 2a grounded to the ground by the electric field. Then, charged particles having a particle size equal to or smaller than the particle size set by the voltage applied by the voltage source 5 are taken into the inner conductor 2a, and a current flows between the inner conductor 2a and the outer conductor 2b (step S5).

  When a current flows through the charged particles taken into the inner conductor 2a, the current value is measured by the ammeter 4. The measurement value of the ammeter 4 is automatically acquired by the current value acquisition unit 12, and the current value acquisition unit 12 outputs the acquired current value to the particle size calculation unit 15 and the dew condensation detection unit 16 (step S6).

  The dew condensation detection unit 16 calculates the capacitance C1 inherent to the concentric cylindrical electrode 2 from the measurement conditions input using the input unit 13 using the equation (4), and stores it in a storage unit (not shown) ( Step S7). The process of step S7 for calculating the capacitance C1 need only be performed once every time measurement conditions are input using the input unit 13, and thereafter, the value of the capacitance C1 is read from the storage unit. good.

  Also, the dew condensation detection unit 16 uses the above equation (5) from the applied voltage V input from the particle size calculation unit 15, the current value is acquired from the current value acquisition unit 12, and the acquired time t. The actual capacitance C2 is calculated and stored in the storage unit (step S8), and the presence or absence of condensation is determined by comparison with the specific capacitance C1 obtained in step S7 (step S9). That is, the dew condensation detection unit 16 determines whether or not the intrinsic capacitance C1 obtained from the shape and size of the concentric cylindrical electrode 2 and the actual capacitance C2 match, and if they do not match. (In other words, when the absolute value of the difference between capacitances C1 and C2 exceeds a predetermined threshold value), a dew condensation detection signal indicating the occurrence of dew condensation is output to particle size calculation unit 15 and warm-up operation control unit 18 (step S10). ).

  Here, when the condensation detection signal is input from the condensation detection unit 16, the particle size calculation unit 15 immediately stops the evaluation of the charged particle amount, and the voltage control unit 11 sets the voltage of the voltage source 5 to zero ( Step S15), the applied voltage immediately before the stop of the evaluation is stored in a storage unit (not shown).

  When the dew condensation detection signal is input from the dew condensation detection unit 16, the warm air operation control unit 18 outputs a polarity switching signal to the air flow control unit 17 and starts a power on signal to the heater 7 in order to start the warm air operation. Is output (step S16). At this time, the airflow control unit 17 switches the polarity of the voltage source 6 from positive to negative in accordance with the polarity switching signal input from the warming-up operation control unit 18, and changes the direction of airflow generation by the intake fan 3 to the charged particle amount. The direction is switched to the direction opposite to the airflow generation direction at the time of evaluation (that is, the direction from the intake fan 3 toward the concentric cylindrical electrode 2) (step S17). In the heater 7, when a power-on signal is input from the warm-up operation control unit 18, the power is turned on to generate heat and warm the surrounding air (step S18). Thus, the air on the intake side of the intake fan 3 is warmed by the heater 7, and the air heated by the heater 7 is sucked into the intake fan 3 and blown into the annular space 2 c of the concentric cylindrical electrode 2. Therefore, the inner conductor 2a and the outer conductor 2b of the concentric cylindrical electrode 2 are warmed (step S19).

  Thereafter, when the warm-up operation time input from the input unit 13 has elapsed since the start of the warm-up operation, the warm-up operation control unit 18 outputs a polarity switching signal to the air flow control unit 17 and stops the heater operation in order to stop the warm-up operation. 7 outputs a power stop signal, and further outputs a warm-up end signal to the dew condensation detection unit 16 (step S20). At this time, the airflow control unit 17 switches the polarity of the voltage source 6 from negative to positive according to the polarity switching signal input from the warm-up operation control unit 18, and changes the direction of airflow generation by the intake fan 3 from the intake fan 3. The direction is changed from the direction toward the concentric cylindrical electrode 2 to the direction of air flow generation when the charged particle amount is evaluated (step S21). Further, in the heater 7, when the power supply stop signal is input from the warm-up operation control unit 18, the power supply is stopped and the heating of the air is finished (step S22). Furthermore, when the warming-up end signal is input from the warming-up operation control unit 18, the dew condensation detection unit 16 stops outputting the dew condensation detection signal (step S23), and the application immediately before the evaluation stop stored in the storage unit (not shown). The voltage is output to the voltage controller 11 (step S24), and the process returns to the above-described steps S4 to S9 to detect the presence or absence of condensation again. At this time, when the dew condensation detection unit 16 detects dew condensation again and outputs a dew condensation detection signal to the particle size calculation unit 15 and the warm air operation control unit 18, the warm air operation control unit 18 again performs the process of the warm air operation in steps S10 to S23. Is done.

  On the other hand, when the condensation detection unit 16 determines that there is no condensation in the determination of step S9, and the condensation detection signal is not input to the particle size calculation unit 15, the particle size calculation unit 15 is input from the current value acquisition unit 12. From the current value is, the number of charged particles having a particle size equal to or smaller than the minimum particle size is calculated using the above-described equation (3), and the particle size and the number of charged particles to be measured are stored in a storage unit (not shown) (step) S11). At this time, the particle size calculation unit 15 may store the particle size and the number of charged particles to be measured in a storage unit, and may output them to an output device (not shown) such as a printer.

  When the particle size and the number of charged particles to be measured are stored in the storage unit, the particle size calculation unit 15 determines whether or not the measurement has been completed for all measurement ranges (step S12), and the measurement must be completed. For example, after outputting the voltage value and polarity of the applied voltage when the particle size is increased by a predetermined sweep width to the voltage control unit 11 and the dew condensation detection unit 16 (step S13), the processing of the above steps S4 to S11 is performed. repeat. Since the sweep width is 0.2 nm in the particle size range of 0.6 to 2 nm, the voltage value of the applied voltage when the particle size is 0.8 nm is output next to the minimum particle size (0.6 nm). .

  In this device, the number of particles is calculated by repeating the above-described processing S4 to S13 at each particle size setting value every time the particle size is swept by a predetermined sweep width from 0.6 nm to 28 nm. Then, the particle size distribution (the distribution of the number with respect to the particle size) is obtained, and if it is determined in step S12 that the measurement has been completed in the entire measurement range, the particle size calculation unit 15 obtains the calculation result of the particle size distribution. While memorize | storing in a memory | storage part, a measurement result is output to an output device (step S14).

  As described above, in the charged particle amount evaluation apparatus 1 according to the present embodiment, when the dew condensation detection unit 16 detects dew condensation on the inner conductor 2a and the outer conductor 2b, the warming operation control unit 18 performs the warming operation and warms the heater 7. The intake air is sucked by the intake fan 3 and blown into the annular space 2c of the concentric cylindrical electrode 2 to remove condensation on the inner conductor 2a and the outer conductor 2b. As a result of the warm-up operation, condensation is detected. When it disappears, the charged particle amount is evaluated by the particle size calculation unit 15, so that the charged particle amount can be evaluated with higher accuracy. Further, until the dew condensation detection unit 16 detects no dew condensation, the warm-up operation control unit 18 repeats the operation of performing the warm-up operation for the warm-up operation time. Therefore, the warm-up operation is resumed in as short a time as possible to evaluate the charged particle amount. Can be done.

(Embodiment 3)
Embodiment 3 of the present invention will be described below. In the charged particle amount evaluation apparatus 1 described in the second embodiment, the air volume of the intake fan 3 is set to a constant air volume. However, in this embodiment, the air flow control unit 17 is provided with a function of changing the air volume of the intake fan 3 so that warm air is supplied. The operation control unit 18 uses the airflow control unit 17 to increase the air flow rate of the intake fan 3 to a predetermined flow rate larger than the air flow rate at the time of evaluating the charged particle amount for a predetermined time during the warm-up operation. In addition, since the structure of the charged particle amount evaluation apparatus 1 is the same as that of Embodiment 2, the same code | symbol is attached | subjected to a common component and the description is abbreviate | omitted.

  In the airflow control unit 17, the airflow generation direction and the amount of air blown by the intake fan 3 are changed by changing the polarity and voltage value of the voltage source 6 according to the polarity and voltage value of the input signal from the warm-up operation control unit 18. I am letting.

  In addition to the function described in the second embodiment, the warm-up operation control unit 18 increases the air flow rate of the intake fan 3 to a predetermined flow rate larger than the air flow rate at the time of evaluating the charged particle amount for a predetermined time during the warm-up operation. The function to output the signal to be sent to the airflow control unit 17 is provided.

  Since the operation of the charged particle amount evaluation apparatus 1 is the same as that of the second embodiment except during the warming-up operation, the description thereof will be omitted, and the operation during the warming-up operation will be described below with reference to FIG.

  When the dew condensation detection unit 16 determines that there is dew condensation as a result of the determination in step S9, a dew condensation detection signal indicating the occurrence of dew condensation is output to the particle size calculation unit 15 and the warm-up operation control unit 18 (step S10).

  Here, when the condensation detection signal is input from the condensation detection unit 16, the particle size calculation unit 15 immediately stops the evaluation of the charged particle amount, and the voltage control unit 11 sets the voltage of the voltage source 5 to zero ( Step S15), the applied voltage immediately before the stop of the evaluation is stored in a storage unit (not shown).

  When the dew condensation detection signal is input from the dew condensation detection unit 16, the warm air operation control unit 18 outputs a polarity switching signal to the air flow control unit 17 and starts a power on signal to the heater 7 in order to start the warm air operation. Is output (step S16). At this time, the airflow control unit 17 switches the polarity of the voltage source 6 from positive to negative in accordance with the polarity switching signal input from the warming-up operation control unit 18, and changes the direction of airflow generation by the intake fan 3 to the charged particle amount. It switches to the direction opposite to the airflow generation direction at the time of evaluation (step S17). In the heater 7, when a power-on signal is input from the warm-up operation control unit 18, the power is turned on to generate heat and warm the surrounding air (step S18). Thus, the air on the intake side of the intake fan 3 is warmed by the heater 7, and the air heated by the heater 7 is sucked into the intake fan 3 and blown into the annular space 2 c of the concentric cylindrical electrode 2. Therefore, the inner conductor 2a and the outer conductor 2b of the concentric cylindrical electrode 2 are warmed (step S19).

  Here, the warming-up operation control unit 18 sets the air flow rate (flow rate) of the intake fan 3 for the predetermined amount of time (for example, 20% of the warming-up operation time) in the warming-up operation time input by the input unit 13. A control signal for increasing the flow rate to a predetermined flow rate (for example, a flow rate increased by 50% at the time of charged particle amount evaluation) larger than the air flow rate at the time of evaluation is output to the airflow control unit 17. The airflow control unit 17 controls the applied voltage of the voltage source 6 so as to increase the flow rate of the intake fan 3 to a predetermined flow rate for a predetermined time according to the control signal input from the warm-up operation control unit 18. The intake fan 3 changes the flow rate according to the applied voltage of the voltage source 6 and increases the air flow rate to a predetermined flow rate for a predetermined time during the warming-up operation. Return to flow rate.

  Thereafter, when the warm-up operation time input from the input unit 13 has elapsed since the start of the warm-up operation, the warm-up operation control unit 18 outputs a polarity switching signal to the air flow control unit 17 and stops the heater operation in order to stop the warm-up operation. 7 outputs a power stop signal, and further outputs a warm-up end signal to the dew condensation detection unit 16 (step S20). At this time, the airflow control unit 17 switches the polarity of the voltage source 6 from negative to positive according to the polarity switching signal input from the warm-up operation control unit 18, and changes the direction of airflow generation by the intake fan 3 from the intake fan 3. The direction is changed from the direction toward the concentric cylindrical electrode 2 to the direction of air flow generation when the charged particle amount is evaluated (step S21). Further, in the heater 7, when the power supply stop signal is input from the warm-up operation control unit 18, the power supply is stopped and the heating of the air is finished (step S22). Furthermore, when the warming-up end signal is input from the warming-up operation control unit 18, the dew condensation detection unit 16 stops outputting the dew condensation detection signal (step S23), and the application immediately before the evaluation stop stored in the storage unit (not shown). The voltage is output to the voltage controller 11 (step S24), and the process returns to the above-described steps S4 to S9 to detect the presence or absence of condensation again. At this time, when the dew condensation detection unit 16 detects dew condensation again and outputs a dew condensation detection signal to the particle size calculation unit 15 and the warm air operation control unit 18, the warm air operation control unit 18 again performs the process of the warm air operation in steps S10 to S23. Is done.

  As described above, in the present embodiment, a function of changing the air flow rate of the intake fan 3 is added to the air flow control unit 17, and the warm air operation control unit 18 uses the air flow control unit 17 for a predetermined time during the warm air operation. Since the air blowing amount of the intake fan 3 is increased to a predetermined flow rate larger than the air blowing amount at the time of evaluating the charged particle amount, dew condensation is removed by blowing hot air, and the flow rate is higher than at the time of evaluating the charged particle amount. By blowing a large laminar flow, dust and dirt attached to the inner conductor 2a and the outer conductor 2b can be blown off, and the amount of charged particles can be evaluated with higher accuracy.

  It should be noted that a wide variety of different embodiments can be configured without departing from the spirit and scope of the present invention, and the present invention is not limited to a specific embodiment.

1 is a schematic configuration diagram of a charged particle amount evaluation apparatus according to Embodiment 1. FIG. It is a flowchart explaining operation | movement same as the above. 6 is a schematic configuration diagram of a charged particle amount evaluation apparatus according to Embodiment 2. FIG. It is a flowchart explaining operation | movement same as the above. It is a schematic block diagram of the conventional charged particle amount evaluation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charged particle amount evaluation apparatus 2 Concentric cylindrical electrode 2a Inner conductor 2b Outer conductor 3 Intake fan (air flow generation means)
4 Ammeter (Current measurement means)
5 Voltage source (voltage application means)
10 controller 14 arithmetic processing unit 15 particle size calculation unit (charged particle amount evaluation means)
16 Condensation detection unit (condensation detection means)

Claims (5)

  A concentric cylindrical electrode configured by concentrically arranging a cylindrical inner conductor and a cylindrical outer conductor having a diameter larger than that of the inner conductor, and an axis of the concentric cylindrical electrode in a space between the inner conductor and the outer conductor. An airflow generating means for generating a laminar flow in the direction, a voltage applying means for applying a voltage between the inner conductor and the outer conductor, a current measuring means for measuring a current flowing between the inner conductor and the outer conductor, and a layer Condensation detection means for detecting the presence or absence of condensation occurring on the inner conductor and outer conductor forming the wall of the flow path, and the shape and dimensions of the concentric cylindrical electrode when no condensation is detected by the condensation detection means. Charged particle amount evaluation means comprising charged particle amount evaluation means for evaluating the amount of charged particles based on the flow rate of laminar flow by the airflow generation means, the applied voltage by the voltage application means, and the measurement result of the current measurement means apparatus.   A heater arranged in the middle of the laminar flow path and downstream of the concentric cylindrical electrode in the air flow generation direction when evaluating the amount of charged particles, and the air flow generation direction by the air flow generation means When the dew condensation detection means detects dew condensation, and when the dew condensation detection means detects dew condensation, the air is heated by a heater and the air flow generation direction by the air flow generation means is evaluated by using the air flow direction switching means. 2. The charged particle amount evaluation apparatus according to claim 1, further comprising a warming-up operation control unit that performs a warming-up operation that switches in a direction opposite to the time.   3. The charged particle amount evaluation apparatus according to claim 2, wherein the warm-up operation control unit continues the warm-up operation until the dew condensation detection unit detects that there is no dew condensation.   Airflow control means for changing the air flow rate of the airflow generation means is provided, and the warm-up operation control means uses the airflow control means for a predetermined time during the warm-up operation to evaluate the air flow rate of the airflow generation means when evaluating the charged particle amount. The charged particle amount evaluation apparatus according to claim 2, wherein the flow rate is increased to a predetermined flow rate larger than the air flow rate.   The dew condensation detection means includes an amount of charge stored in the concentric cylindrical electrode obtained from the measurement result of the current measurement means and a capacitance obtained from an applied voltage by the voltage application means, a shape of the concentric cylindrical electrode, and The occurrence of dew condensation is detected because the absolute value of the difference between the two is compared with a capacitance obtained from the dimensions and exceeds a predetermined threshold value. The charged particle amount evaluation apparatus described.

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