JP3915534B2 - Dry particle size analyzer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser diffraction / scattering particle size distribution measuring apparatus, and more particularly to a so-called dry laser diffraction / scattering particle size distribution measuring apparatus using air as a dispersion medium for dispersing a group of particles to be measured.
[0002]
[Prior art]
In the laser diffraction / scattering particle size distribution measurement method, generally, the spatial intensity distribution of diffracted / scattered light generated by irradiating a group of particles in a dispersed flight state with laser light is measured. Using the scattering theory or the Fraunhofer diffraction theory, the particle size distribution of the particle group to be measured is calculated from the measurement result of the spatial intensity distribution of the diffracted / scattered light by calculation based on the Mie scattering theory or the Fraunhofer diffraction theory.
[0003]
In this type of conventional particle size distribution measurement method, there are known wet measurement in which a liquid is used as a medium for dispersing the particles to be measured in a suspension state and dry measurement in which a gas is used in an aerosol state. ing. The dry measurement is mainly used for measuring a granular material that is easily dissolved in a liquid such as a medicine.
[0004]
A conventional laser diffraction / scattering particle size distribution analyzer for dry measurement uses an irradiation optical system that irradiates laser light onto a group of particles to be measured, and the spatial intensity distribution of the diffracted / scattered light generated by the laser light irradiation. As a device for supplying the particles to be measured in the form of an aerosol between the measuring optical system to be measured, the following system is employed.
[0005]
One of them is to provide a groove on the surface of a disk-shaped sample table to which rotation is provided along an arc centered on the center of rotation, and to place a suction device adjacent to the sample table. With the configuration in which the mouth faces the groove, the particles to be measured that have been placed in the groove prior to measurement are sequentially supplied to the lower part of the suction port by the rotation of the sample stage, and are sucked from the suction port. System that guides the measured particle group through a pipe to a dispersion nozzle that opens toward the measurement space between the irradiation optical system and the measurement optical system, and supplies the measurement particle group in an aerosol form from the dispersion nozzle to the measurement space It is. In some cases, the groove is linear, and the particles to be measured in the groove are sequentially sucked by a linear motion.
[0006]
The other is a path in which a hopper for introducing a group of particles to be measured is provided above the measurement space between the irradiation optical system and the measurement optical system, and the lower end of the hopper and the measurement space are closed. In this method, the particles to be measured in the hopper are sequentially supplied to the measurement space in an aerosol form by sucking the particles to be measured from one end of the passage.
[0007]
[Problems to be solved by the invention]
By the way, in the conventional dry laser diffraction / scattering type particle size distribution measuring apparatus as described above, it is necessary to set the particles to be measured in a groove on a sample table or in a hopper. There is a problem that it takes time and effort. In addition, there is a problem that the particle group may be spilled when the particle group to be measured is set on the sample stage or the hopper, and a wasteful sample is generated. Further, some particle groups cannot be easily set on a sample stage or the like, and such particle groups may not be measured by this type of conventional measuring apparatus.
[0008]
Furthermore, after completing the measurement of a sample of a certain type, it is necessary to clean the sample stage and the hopper when measuring a sample of a different type, and in particular, the group of particles to be measured put into the hopper. There is a problem that it is difficult to clean the suction method through the closed passage.
[0009]
The present invention has been made in view of such circumstances, and it is easy to set the particle group to be measured on the sample stage or the hopper, and thus without taking time and without spilling and wasting at the time of setting. can perform a two-particle size distribution measurement, moreover, it is possible to suction and measurement of the particles to be measured by hand operation, and aims to provide a can Ru dry particle size distribution measuring apparatus to significantly improve the convenience of use .
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the dry particle size distribution measuring apparatus of the present invention comprises an irradiation optical system for irradiating laser light to a group of particles in a dispersed flight state, and diffraction / scattered light of the laser beam by the group of particles to be measured. A measurement optical system for measuring the spatial intensity distribution of the sample, and a calculation means for calculating the particle size distribution of the group of particles to be measured from the measurement results, and in the measurement space between the irradiation optical system and the measurement optical system, In the dry particle size distribution measuring apparatus, the particles to be measured are sucked by a suction means using suction force generated by supplying compressed air and supplied in an aerosol state through a nozzle.
The suction port of the particle group to be measured of the suction means is movably connected via a flexible tube to a nozzle fixed so as to open toward the measurement space, and is connected to the ejector of the suction means. A pressure regulating valve that doubles as an on-off valve for supplying compressed air and that adjusts the concentration of the particle group to be measured supplied in aerosol form to the measurement space is provided integrally with the suction port. Characterized.
[0011]
The present invention is configured so that the suction port for sucking the group of particles to be measured and leading to the measurement space can be freely moved, instead of being fixedly arranged above the sample stage as in the prior art. It is configured so that the existing sample can be sucked and guided to the measurement space, and the start / stop of the suction of the group of particles to be measured by the suction means mainly composed of an ejector and the aerosol are supplied integrally with the suction port. By providing an operation unit for controlling the suction operation including pressure adjustment for adjusting the concentration of the particles to be measured, the intended object is to be achieved.
[0012]
That is, for sucking the sample group to be measured and guiding it to the nozzle that is fixed so as to spray the sample group to be measured in an aerosol shape toward the measurement space between the irradiation optical system and the measurement optical system By adopting a configuration in which the suction port of the suction means using the ejector is movably connected via a flexible tube, a sample at an arbitrary position can be sucked and guided to the measurement space. Specifically, for example, it is possible to measure the particle size distribution by directly sucking from the container containing the particle group to be measured, greatly reducing the time and labor for setting the particle group to be measured on the sample stage or hopper. In addition to being able to be omitted, it is possible to prevent waste due to spilling when setting the particle group to be measured on the sample stage or hopper. The particle size distribution can be measured by moving the suction port for suction. Furthermore, since it is not necessary to use a sample stage, a hopper, etc., the cleaning work is also unnecessary.
[0013]
In addition, the operation unit for controlling the suction operation including the start / stop of the suction of the particles to be measured, specifically, the open / close valve of the compressed air to the ejector that generates the suction pressure, and the aerosol in the measurement space In a state where the suction port is moved so as to suck the sample at an arbitrary position, by providing a pressure adjustment valve integrally with the suction port for adjusting the concentration of the particles to be measured supplied in a shape, It is possible to control the suction of the particle group to be measured and the concentration adjustment of the particle group to be measured by hand operation on the spot, and the convenience of use can be greatly improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a configuration of an optical system and a particle sampling / dispersion system, and a block diagram showing an electrical configuration.
[0015]
The irradiation optical system 1 includes a laser light source 1a, a condensing lens 1b, a spatial filter 1c, and a collimator lens 1d. The irradiation optical system 1 is in a measurement space A in which a measured particle group P is supplied in an aerosol state by a particle sampling / dispersing system 6 described later. A parallel laser beam is irradiated.
[0016]
On the side opposite to the irradiation optical system 1 across the measurement space A, a measurement optical system 2 mainly including a condensing lens 2a and a ring detector 2b placed at the focal position thereof is arranged. The ring detector 2b is a photosensor array in which a plurality of photosensors having ring-shaped, semi-ring-shaped, or quarter-ring-shaped light receiving surfaces with different radii are arranged concentrically, and the output of each photosensor is Among the diffracted / scattered light of the laser beam by the aerosol-measured particle group P supplied in the measurement space A, the diffracted / scattered light in the predetermined forward angle range collected by the condenser lens 2a for each angle. This represents the intensity signal. Therefore, the measurement optical system 2 measures the spatial intensity distribution of the diffracted / scattered light by the group of particles to be measured P that are in a dispersed flight state in the measurement space A. In this figure, only the ring detector 2b is shown as an optical sensor of the measurement optical system 2, but in addition to this, it is necessary to measure the spatial intensity distribution of diffracted / scattered light in a wider angular range. In this case, a single light sensor is arranged corresponding to the required scattering angle to measure the spatial intensity distribution of diffracted / scattered light as a front wide angle scattered light sensor, a side scattered light sensor, and a back scattered light sensor. Can also be provided.
[0017]
The light intensity detection signal for each diffraction / scattering angle by the measurement optical system 2 is amplified by the data sampling circuit 3 having the respective amplifiers and AD converters, digitized, It is taken into the computer 4 as spatial intensity distribution data of scattered light.
[0018]
The computer 4 uses the spatial intensity distribution data of the diffracted / scattered light to detect the laser light by a calculation method based on the Mie scattering theory and the Fraunhofer diffraction theory, which is known in a laser diffraction / scattering particle size distribution measuring apparatus. The particle size distribution of the particle group P to be measured, which is the cause particle that has been diffracted and scattered, is calculated.
[0019]
The irradiation optical system 1 and the measurement optical system 2 described above are accommodated in a light shielding case 5 including the measurement space A between them, and in the measurement space A in the case 5, the particle sampling The particle group P to be measured is supplied in an aerosol state by the dispersion system 6.
[0020]
The particle sampling / dispersing system 6 includes a dispersion nozzle 6 a fixed to the case 5 in a posture orthogonal to the optical axis of the irradiation optical system 1 toward the measurement space A, and high-pressure air from a compressed air source (not shown). An ejector 6b that generates a vacuum in an internal suction chamber by being supplied, a suction port 6c having one end communicating with an intake port of the ejector 6b and opening the other end, an exhaust port of the ejector 6b, and a dispersion nozzle 6a The flexible tube 6d having a sufficient length to communicate with each other is mainly used.
[0021]
A piping for supplying high pressure air to the ejector 6b is also a flexible tube 6e, and a pressure regulating valve 7 serving as an on-off valve is mounted between the flexible tube 6e and the high pressure air supply port of the ejector 6b. ing.
[0022]
Further, the case 5 described above is provided with a suction port 8 facing the dispersion nozzle 6a and communicating with a dust collector (not shown).
[0023]
When using the embodiment of the present invention described above, the ejector 6b and the suction port 6c are held by hand, for example, the suction port 6c is brought into the container V containing the sample group P to be measured as shown in the figure, and the pressure The adjusting valve 7 is operated to suck the sample group P to be measured. As a result, the sample group P to be measured passes through the flexible tube 6d and is sprayed in an aerosol form from the dispersion nozzle 6a toward the measurement space A, and the laser beam from the irradiation optical system 1 is diffracted and scattered by the particle group P to be measured. To do. The spatial intensity distribution of the diffracted / scattered light is measured by the measurement optical system 2, and the measurement result is taken into the computer 4 and converted into the particle size distribution of the particle group P to be measured. Further, the particle group P to be measured supplied toward the measurement space A is guided to the dust collector from the suction port 8 disposed so as to face the dispersion nozzle 6a, and is captured by the filter inside the dust collector.
[0024]
The point to be particularly noted in the above embodiment is that the ejector 6b and the suction port 6c can be arbitrarily moved. As a result, the sample P to be measured can be placed in any container V as shown in FIG. Can be used for particle size distribution measurement. At this time, the suction amount of the measured particle group P, in other words, the concentration of the measured particle group P supplied to the measurement space A in an aerosol form depends on the pressure of the high-pressure air supplied to the ejector 6b. Since the air pressure adjusting valve 7 is integrally mounted on the ejector 6b and the suction port 6c, the operation thereof is also simple.
[0025]
【The invention's effect】
As described above, according to the present invention, in the dry laser diffraction / scattering particle size distribution measuring apparatus for measuring the spatial intensity distribution of the diffracted / scattered light by supplying the particles to be measured from the nozzle to the measurement space in the form of aerosol Since the suction port of the particle group to be measured is configured to be freely movable with respect to the nozzle, the particle group to be measured contained in an arbitrary container or the like is directly sucked and used for measurement, Alternatively, the particle size distribution can be measured by directly sucking a particle group at an arbitrary position in the production line of the granular material. As a result, it is possible to save the labor and time for setting the particle group to be measured in the groove or hopper on the sample table as in the past and waste of the particle group that may have occurred during the setting. The particle size distribution can be measured with a smaller amount of sample. In addition, the particle size distribution can be measured for a particle group that cannot be set on the sample stage or the like.
[0026]
In addition, it is not necessary to clean the sample stage or hopper when measuring different types of particles, and it is possible to perform continuous measurement simply by preparing a container for each type of particle. Together with the fact that setting on a sample stage or the like is unnecessary, the labor required for measurement can be greatly reduced, and at the same time, the required time can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram illustrating a configuration of an optical system and a particle sampling / dispersion system, and a block diagram illustrating an electrical configuration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Irradiation optical system 2 Measurement optical system 3 Data sampling circuit 4 Computer 5 Case 6 Particle sampling / dispersion system 6a Dispersion nozzle 6b Ejector 6c Suction port 6d Flexible tube 7 Pressure adjustment valve A Measurement space P Particle group to be measured

Claims (1)

Irradiation optical system that irradiates laser beam to a group of particles to be measured in a dispersed flight state, measurement optical system that measures the spatial intensity distribution of diffracted / scattered light from the laser particle group to be measured, and measurement results from the measurement results Computation means is provided for calculating the particle size distribution of the particle group, and is covered by suction means using suction force generated by supplying compressed air to the ejector in the measurement space between the irradiation optical system and the measurement optical system. In the dry particle size distribution measuring device that sucks the measurement particles and supplies them in an aerosol state through a nozzle,
The suction port of the particle group to be measured of the suction means is movably connected via a flexible tube to a nozzle fixed so as to open toward the measurement space, and is connected to the ejector of the suction means. A pressure regulating valve that doubles as an on-off valve for the compressed air to be supplied and that adjusts the concentration of the particles to be measured supplied in an aerosol form to the measurement space is provided integrally with the suction port. A dry particle size distribution measuring device.

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