JPH0312540A - Instrument for measuring grain size distribution - Google Patents

Abstract

PURPOSE:To make repetitive measurement with the shorter time for processing, simple processing software and easy automation, etc., by detecting the distance between the two luminescent spots of the reflected light image-formed by an optical image forming system and a transmitted and refracted light. CONSTITUTION:This instrument is constituted of a catching surface to catch a liquid drop 1, an image forming section, a data processing section 8, a parallel moving section and 1st, 2nd, 3rd light sources 3 to 5. The light source 3 irradiates the entire part of the catching surface with light in order to observe the image of entire part of the liquid drop. The light sources 4, 5 irradiate the catching surface at an equal angle theta from diagonal below the catching surface. The image of the liquid drop 1 is converged by a lens 6 and is image- formed on a one-dimensional optical sensor 7. The image data is taken into the data processing section 8 which computes the grain size and grain size distribution of the liquid drop. The grain size distribution of the liquid drop is, therefore, exactly and automatically measured by the image processing of the short period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a particle size distribution measuring device that measures the particle size distribution of dropping droplets.

[Prior Art] A liquid immersion method is conventionally known as a method for determining the particle size distribution of droplets.

This immersion method usually involves coating a glass plate with a thin layer of relatively high viscosity liquid, allowing droplets to jump into the liquid, and measuring the diameter of each droplet as it sinks into the liquid in the form of a perfect sphere. This is a method of determining the particle size distribution, etc. of the collected droplet group.

In such liquid immersion methods, the image of the liquid present in the receiver and stopper liquid is captured using, for example, a drum scanner method, a method using a two-dimensional sensor of the TV left camera, or a method using a one-dimensional optical sensor that is moved perpendicular to the sensor row. Image data is obtained using this method, and by scanning this image data, two-dimensional image data regarding the droplet is processed to determine the diameter and volume of the liquid.

[Problems to be Solved by the Invention] As described above, processing two-dimensional image data has the disadvantage that it takes a long time to determine the diameter of a droplet, etc. because the amount of data to be processed is extremely large. . On the other hand, in order to process two-dimensional image data in a short time, a dedicated image analysis device and complicated software were required.

Therefore, the technical problem of the present invention is to provide a particle size distribution measuring device that can accurately and automatically measure the particle size distribution of droplets using a liquid immersion method through short-time image processing. It is in.

[Means for Solving the Problems] According to the present invention, there is provided a receiving section that forms a predetermined droplet receiving surface, and at least one receiving section that allows incident light to enter at a predetermined angle with respect to the receiving surface. an optical imaging system that images transmitted refracted light and reflected light of the incident light obtained by passing the incident light onto the droplet on the receiving surface;
an image forming section that detects a distance between two bright spots of reflected light and transmitted refracted light imaged by the optical imaging system; a moving section that moves the receiving section in a horizontal direction; and a moving section that moves the receiving section in a horizontal direction; A particle size distribution characterized in that it has a processing section that controls the movement of the section and calculates droplet size and droplet size distribution based on the detected value from the image forming section and the magnification of the optical imaging system. A measuring device is obtained.

[Function] In the particle size distribution measuring device of the present invention, at least 1
Two light sources are emitted from below the liquid layer received by the receiving surface.
Incident light is made to enter at a predetermined intersection angle.

The image forming unit has an optical imaging system that images transmitted refracted light and reflected light of the light scattered by the droplets, and images the transmitted refracted light and reflected light formed by the optical imaging system. Detect the distance between two bright spots.

The moving section moves the receiving section in the horizontal direction.

The processing section controls the movement of the moving section and calculates the droplet size and droplet size distribution based on the detected value from the image forming section and the magnification of the optical imaging system.

[Example] FIG. 1 is a diagram showing a particle size distribution measuring device according to an example of the present invention.

In this figure, the particle size distribution measuring device includes a receiving section, an image forming section, a data processing section 8, a parallel moving section, and a first...
Second. A third light source 3, 4.5 is provided.

The receiving portion has a slide glass 2 on which a receiving surface 2a is formed by applying a stopper liquid (not shown) such as silicone oil to stop the droplet 1 from being received.

The first light source 3 is placed directly below the slide glass 2 to observe the entire edge of the liquid layer, and irradiates the entire receiving surface with light.

The second and third light sources 4 and 5 illuminate the receiving surface obliquely from below at an equal angle θ.

The image forming section includes a lens 6 arranged to face the first light source with a slide glass 2 interposed therebetween, and a one-dimensional optical sensor 7 provided with its optical axis aligned with the optical axis 10 of this lens 6. have

Furthermore, the data processing section 8 is connected to a one-dimensional sensor.

The parallel movement unit 9 is connected to the data processing unit 8 and includes a drive control circuit 9a for moving the slide glass 2 and an actuator 9b driven by the drive control circuit 9a.

In the particle size distribution measuring device having such a configuration, the image of the droplet 1 on the receiving surface is focused by the lens 6 and formed on the one-dimensional optical sensor 7. This pixel data of the -dimensional optical sensor 7 is taken into the data processing section 8. The data processing unit 8 includes a storage unit that stores pixel data as necessary, a calculation unit that calculates the particle size and particle size distribution of droplets from this pixel data, and a parallel movement unit 9 that corresponds to the pixel data. It is configured by a CPU including a control section that sends out control signals.

Note that this control section applies a control signal to the drive control circuit 9a of the parallel movement section 9 according to a predetermined program,
The drive control circuit 9a of the parallel movement unit 9
b to move the slide glass 2 in a direction perpendicular to the plane of the paper.

The case where the particle size distribution of droplets is measured using the particle size distribution n1 constant device shown in FIG. 1 will be explained with reference to FIG.

FIG. 2(a) is a diagram showing a two-dimensional image of a droplet formed by the lens 6 on the surface on which the -dimensional sensor 7 is placed.

As shown in Figure 2(a), a spherical droplet 21.2
2.23 is displayed as a circular image on the two-dimensional receiving surface. Each droplet of circular shape 21.22.2
A pair of points 24.degree. 25: points 26, 27; points 28, 29 shown within 3 indicate respective bright spots appearing by the second light source or the third light source.

First, regarding the operation of the droplet detection and measurement device, a case will be described in which only the third light source 5 is turned on.

(The case of having a plurality of light sources will be described later.) First, the first light source 3 is turned on to illuminate the measurement portion of the receiving surface. At this time, the image forming section moves in conjunction with the first light source 3 by a moving mechanism (not shown), and always maintains a position facing the first light source 3. are doing. When the measuring part is reached, the first light source 3 is turned off. Next, when the third light source 5 is turned on and the parallel moving unit 9 is driven to temporarily move the receiving surface, the scanning 1 as shown in FIG. , 2, 3.4 will be performed sequentially.

These scans 1, 2, 3.4 are performed with a width of ΔY.

During each scan 1, 2, 3.4, the second
The optical signals shown in Figure (b) are obtained.

To explain this while comparing FIGS. 2(a) and (b), in FIG. 2(a), during scanning 1, the bright spot 28 of the droplet 23
, 29 are detected by the sensor, and a pair of large and small luminance signals having a peak corresponding to the light intensity of the bright spot as shown in scan 1 in FIG. 2(b) is output. Since the intensity of the reflected light is smaller than the intensity of the transmitted refracted light, it is detected as a peak smaller than the peak of the transmitted refracted light.

Next, in the case of scan 2 in which the slide glass 2 is moved by a predetermined distance ΔY, there are droplets within this range, but there are no bright spots, so no signal with a peak is output.

Furthermore, in the case of scan 3, which is moved by a predetermined interval ΔY from the position of scan 2, only the bright spots 26 and 27 are detected by the sensor, and a signal having a peak at a position corresponding to the position of each bright spot is output. , the interval between these peaks is 26.27 bright points
It shows the interval between.

Furthermore, in the case of scan 4 in which the droplet 21 moves by a predetermined interval ΔY, since the diameter of the droplet 21 is large, a signal with a large bright spot interval is output from the one-dimensional sensor 7.

In this way, it can be seen that if there is a droplet, two bright spots with different brightness can be obtained for a single droplet.

If the distance between these two bright spots is known, the diameter of the droplet can be easily determined since the scattering angle and the magnification of the lens are known.

Therefore, in the embodiment, only the bright point information is extracted for each scan, and processed by the data processing unit 8 according to the principle described below to obtain the diameter of the liquid layer.

As for the above-mentioned scanning method, even if the method moves by a certain scanning section ΔY and then stops to obtain data from the optical sensor,
Alternatively, a method may be used in which data from the optical sensor is obtained at regular intervals while moving at a constant speed. In the latter case, the direction of scanning is somewhat oblique, but this does not pose a practical problem.

As described above, detecting and processing only a pair of bright spots as information during each scan yields an extremely small amount of information compared to the conventional method of processing the entire two-dimensional image, so the processing section can be done quickly and easily.

Next, the principle of measuring the distance between two bright spots used in the above embodiment will be described.

The distance r1+r2 between the bright spots on the one-dimensional sensor corresponding to the distance R, +R2 between the bright spots of the droplet as shown in FIG. 3, the magnification m of the optical imaging system, and the incidence of the light source on the droplet. From the angle, it is found (r++r2-m(R1+R2)). here,
To simplify the explanation, the case of the third light source 5 will be explained, but the same applies to the case of the second light source 4.

Although the third light source 5 may be a parallel light source or a convergent light source, it is first assumed to be a parallel light source.

As shown in FIG. 3, by irradiating each droplet with parallel light, the resulting reflected light and transmitted refracted light become bright spots and exit from the droplet, as shown in FIG. 2. Here, if the distances from the droplet center of the reflected light and transmitted refracted light obtained from each droplet are R1 and R2, respectively, the distance between both bright spots is R1+R2.

On the other hand, since the positions of both bright spots are uniquely determined by the refractive index of the droplet and the angle of incidence of the incident light on the droplet, the distance R, +
The diameter of the droplet can be determined from R2. In reality, the reflected light and the transmitted refracted light from the liquid 7a21 are magnified by an optical imaging system and given to the -dimensional optical sensor.

The distance r, +12 between the two bright spots of the reflected light and the transmitted refracted light on the one-dimensional optical sensor is the angle of incidence θ1. The radius R (=r/m) of the droplet is calculated from the following equation (first equation) from θ2 and the magnification m of the optical imaging system.

1 rl +r2 R--... (1st formula)%
Formula% θ1-(π-θ)/2...(2nd formula) θ2-(θ
+2φ)/2 (3rd equation) % equation % n-(1: refractive index) (4th equation) Calculated from sln φ.

As shown in Figure 3, when a parallel light source is used and the light scattered by the droplet is observed from the θ direction, the reflected light is reflected by the droplet 21 at an angle θ1, and the reflected light is incident at an angle θ2 and refracted. Two bright spots appear on the surface of the droplet due to the refracted and transmitted light.

The diameter of the droplet is determined by measuring the distances @R and +R2 between the bright spots at this time (see Japanese Patent Application No. 165111/1982).

Next, a case will be described in which a plurality of light sources such as the second and third light sources 4 and 5 are provided. In this case, it is assumed that convergent light with a flat intensity profile is generated. When this third light source 5 is convergent light, it is formed by transmitting parallel light rays through a lens, and is converged with a convergence angle 2α. The setting position of the -dimensional optical sensor 1 is determined so that this convergence angle 2α is equal to the angle of view 2α of the -dimensional optical sensor 1.

Further, the second light source 4 has a similar configuration to the third light source 5, and is converged with a convergence angle of 2α.

Moreover, a cylindrical lens can be used as the lens for converging parallel light rays mentioned above.

After setting the parallel light source at an angle of θ using the method using the above-mentioned parallel light source, a lens is placed to converge the light.

FIG. 4 is a diagram showing the scattering angle θ when a convergent light beam is incident on a droplet.

In FIG. 4, only converging rays from one light source are shown. In this figure, the AOB is on the focal plane of the one-dimensional sensor, and the 0 point is the center of the optical axis.If we consider points A and B that are off the center of the optical axis, at point A, the parallel ray 11a is When the light is incident, the scattering angle θ becomes θ−δα when viewed from the principal point C of the -dimensional optical sensor. In order to keep θ constant, a convergent light beam 14a that is larger than θ by δα may be incident.

Regarding point B, the scattering angle θ of the parallel ray 11b is θ+δα for the same reason, so in the same way, convergent ray 1 smaller by δα than θ, contrary to the case of the parallel ray 11a.
4b should be incident.

This δα is an angle determined by the field angle of the one-dimensional optical sensor. If light converging at this angle is made incident on the focal plane AOB of the one-dimensional optical sensor, the scattering angle θ will be a constant value at any position. - Exactly the same explanation holds true when another light source is incident from a symmetrical position across the optical axis of the -dimensional sensor. This means that the optical axis center O
It is shown that the bright spots of the reflected light and the transmitted refracted light from the droplet are superimposed at all positions on the focal plane AOB that are deviated from .

The above explanation has been made regarding the case where only the third light source 5 is used, but as shown in FIG. By illuminating from a certain position, the light balance of the two bright spots can be made equal.

The superposition of bright spots when convergent light sources are used as the second and third light sources in FIG. 4 will be described.

In this case, for raindrops located off the center of the optical axis, 2
Bright spots from two light sources can be superimposed. For adjustment at this time, focusing on one droplet, first shift the angle, obtain four bright spots, and then overlap these bright spots. Also, in Figure 1,
Two-dimensional information is scanned by the parallel displacement unit 9 and the one-dimensional sensor 7, but equivalent information can be obtained without the parallel displacement unit 9 and by using a two-dimensional sensor such as a TV camera instead of the -dimensional sensor 7. Obtainable.

[Effects of the Invention] As explained above, in the conventional apparatus, it was necessary to extract droplet information (circle in this case) from the obtained image data. The limit of this method is to obtain a resolution comparable to the pixel pitch.

On the other hand, in the particle size distribution l1llj determination apparatus of the present invention, the information on droplets basically depends on the accuracy of determining the peak position of the bright spot, and high-precision measurement is possible. A resolution of about 10 times that of the previous one can be obtained.

If the size of the droplet is equivalent to m pixels, in the conventional device,
To cut out a circle, it was necessary to target pixel data of approximately m x n. In contrast, the particle size distribution measuring device of the present invention basically only needs to target pixels containing two bright spot data, regardless of the size of the droplet, and requires two-dimensional image processing. It is not a -dimensional process. Therefore, the processing time is extremely short and the processing software is simple.

According to the particle size distribution nj determining apparatus of the present invention, since measurement can be performed on stationary droplets, automation etc. are extremely easy and repeated measurements are also possible.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a particle size distribution measuring device according to an embodiment of the present invention, and Fig. 2 (a) and (b) are used to explain the measurement principle of the particle size distribution measuring device according to an embodiment of the present invention. Figure 3 is an explanatory diagram of scattering when parallel rays enter a droplet,
FIG. 4 is a diagram showing changes in scattering angle when parallel light and convergent light are used. In the figure, 1 is a droplet, 2 is a slide glass, 3,4°5 is a light source, 6 is a lens, 7 is a one-dimensional optical sensor, 8 is a data processing section, 9 is a parallel movement section, 9a is a drive control circuit, 9b is an actuator, 10 is an optical axis, 11.1.1a, llb are parallel rays, 14a and 24b are convergent lights, 21, 22.23
is a droplet, and 24°25.26, 27, and 28.29 are bright spots.

Claims (1)

[Claims] 1. A receiving portion forming a predetermined droplet receiving surface; at least one light source that makes incident light incident at a predetermined angle with respect to the receiving surface; and the receiving portion. It has an optical imaging system that images the transmitted refracted light and the reflected light of the incident light obtained by passing the incident light through the droplet on the surface, and the reflected light and the transmitted refracted light imaged by the optical imaging system. an image forming section that detects the distance between the two bright spots; a moving section that moves the receiving section in the horizontal direction; and a moving section that controls the movement of the moving section and detects the detected value from the image forming section. A particle size distribution measuring device comprising: a processing section that calculates a droplet size and a droplet size distribution based on the magnification of the optical imaging system. 2. The particle size distribution measuring device according to claim 1, wherein the incident light is converged at an angle equal to the angle of view of the optical imaging system. 3. The particle size distribution measuring device according to claim 1, wherein the image forming section includes a one-dimensional optical sensor.