JPS58178241A - Light scattering type counter for floating particles - Google Patents

Abstract

PURPOSE:To increase an amount of measured sample per unit space by a counter wherein a simple means for charging and focusing of the electric field is provided and aerosol is caused to pass through the means. CONSTITUTION:At the time when aerosol introduced from an inlet 11b passes through the corona discharge region produced by a needle electrode 12 and a corona discharge electrode 13, negative ions deposite onto particles in the aerosol so that the particles are charged with negative polarity. These charged particles pass then through electric field focusing electrodes 15, 17 where they undergo a focusing force to be moved toward the axial center of a passing flow. More specifically, those particles locating at the point P and going to move in the direction of A undergo a combined force of a coulomb force and an air current at the point D, so that they move toward the axial center C following the illustrated path. Similarly, those particles going to move from the point P' in the direction of B are focused toward the axial center. Thus, since the particles in the aerosol discharging through an outlet 17a are focused near the axial center, it is required for a light beam irradiating the aerosol to have a width enough to irradiate the axial center part. As a result, it becomes possible to increase the nozzle size using the prior optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light scattering type suspended particle counter, and more specifically, an aerosol to be measured is passed through a beam of light, and the light scattered by individual particles is collected by photoelectronics. This relates to a light scattering type suspended particle counter that captures particles using a converter, detects them as electrical signals, and counts them.

In the light scattering type suspended particle counter, the width W^ of the sample airflow and the width Wt of the light beam need to maintain the relationship WA < WL. This is a necessary condition for detecting the total number of particles in the sample air ejected from the nozzle without missing a count. Therefore, in order to count particles in a large amount of sample air in a short period of time, a wide light beam is required, and the light source and optical system must be large and expensive.

This invention was made in view of the above circumstances.
The main purpose of this invention is to provide a light scattering type suspended particle counting device that can measure a large amount of sample air in a short time by simply adding other devices.

The purpose of this invention is to forcibly charge the particles in the aerosol, pass these charged particles through an electric field whose lines of electric force are directed at the center of the axis of the cylinder, and initially disperse them evenly in the aerosol. The purpose of the present invention is to obtain a light-scattering type suspended particle counting device that can measure a large amount of aerosol in a short time without increasing the size of a conventional optical system by concentrating the particles that were previously used in the cylinder near the axis of the cylinder.

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

FIG. 1 is a schematic diagram of the present invention, in which an aerosol 1 emitted from a dust nozzle and having negatively charged particles is passed through cylindrical electric field focusing electrodes 2a and 2b. Particles in the aerosol 1 then gather in a region 3 near the axis of the cylindrical flow. 4 is a region of airflow that does not contain particles.

FIG. 2 shows an embodiment of the present invention, in which the needle electrode 12 is connected to the insulating member 11a along the central axis of the nozzle 11 made of an insulating material.
be supported and placed. llb is the aerosol inlet. A cylindrical corona discharge electrode 13 is coaxially connected to the lower end of the nozzle 11, and below it a cylindrical insulator 14, a first electric field focusing electrode 15, an insulator 16, and a second electric field focusing electrode are connected. The electrodes 17 are sequentially and coaxially connected and arranged. A corona discharge power source 18 is connected between the needle electrode 12 and the corona discharge electrode 13, and the first and second electric field focusing electrodes 1
An electric field focusing power source 19 is connected between 5 and 17. 17a
is the aerosol outlet.

With the above configuration, when the aerosol passes through the corona discharge region formed by the needle electrode 12 and the corona discharge electrode 13 from the inlet 11b, anions adhere to the particles in the aerosol and the particles are negatively charged. The charged particles then pass through the field focusing electrodes 15, 17 and are subjected to a force that focuses them on the flow axis. To describe this focusing effect in more detail with reference to Figure 3, a particle that was at point P and was moving in the direction of A will move along the trajectory shown in the figure due to the combined force of the Kulovka 1 air flow from point D. to the axis center O. In this case, the inertial force based on the particle's hymn also acts, but we ignore it. point y
Particles heading in the direction B are similarly focused toward the center of the axis. These are all about particles that are moving away from the center of the axis of the flow, but particles that are parallel to the axis or in a direction toward the center of the axis also converge at the center of the collar axis. Since the particles of the aerosol flowing out from the outlet 17a are concentrated near the center of the shaft, the width of the light beam for irradiating the aerosol needs to be sufficient to irradiate the center of the shaft. Therefore, it is possible to increase the nozzle diameter using a conventional optical system.

As described above, according to the present invention, the amount of sample to be measured per unit time can be increased by providing a simple charging and electric field focusing means and passing the aerosol therethrough.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the present invention, FIG. 2 is a longitudinal sectional view of a main part of an embodiment of the present invention, and FIG. 3 is a diagram illustrating the operation. 11 nozzle, Ila insulator, llb inlet, 12 needle electrode, 13 corona discharge electrode, 14 insulator, 15]7 electric field focusing electrode, 16 insulator,
17a - Outlet. Patent applicant Rion Co., Ltd.

Claims (1)

[Scope of Claims] (]) An apparatus for passing a sample aerosol in a beam-like light beam and capturing scattered light by particles in the sample aerosol with a photoelectric converter and detecting and counting it as an electrical signal,
a charging means for negatively charging the particles between the nozzle for ejecting the sample aerosol and the potential beam;
A light scattering type suspended particle counting device comprising an electric field focusing means that directs the negatively charged particles toward the axial center of the aerosol by Coulomb force. (2) A charged electrode is connected to a needle electrode arranged at the center of the nozzle, a cylindrical corona strip connected to the lower end of the nozzle, and a corona connected between the needle electrode and the corona discharge electrode. The light scattering suspended particle meter according to claim 1, which comprises a discharge power source. (3) The electric field focusing means includes cylindrical first and second electric field focusing electrodes coupled via an insulator, and an electric field focusing device connected between the first and second electric field focusing electrodes. A light scattering type suspended particle counting device according to claim 1, which comprises a power source.