JPH05332913A - Manufacture of fixed specimen for inspection reference of particle size distribution measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a manufacturing method for a fixed specimen having particle images aligned at random. CONSTITUTION:According to the manufacturing for a fixed specimen as an inspection reference of a particle size distribution measuring device, an original drawing having a predetermined number of particle images disposed at random on a square screen is formed, and the original drawing is reduced and transferred to obtain a square original picture of a predetermined unit area for photoresist. A plurality of the original pictures are spread over in all directions while the posture in the lengthwise and widthwise directions is changed, thereby to form a photo mask. The photo mask is printed to a transparent substrate 21 to cover the particle images with a film. Accordingly, a fixed specimen 20 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fixed sample used as a calibration standard for a particle size distribution measuring instrument based on a light diffraction method, a light scattering method or the like.

[0002]

2. Description of the Related Art A commonly used optical diffraction type particle size distribution measuring device has a structure as shown in FIG. In the case of the wet measurement, the powder sample to be used for the measurement is put into an appropriate dispersion liquid and sufficiently dispersed in the ultrasonic dispersion tank 9 to be dispersed in the glass cell 6
Is supplied to.

The glass cell 6 is a passage type cell having a supply port and a discharge port, and a measuring section for forming a uniform flow of the dispersion liquid is formed on the way. The ultrasonic dispersion tank 9, the glass cell 6, and the pump 10 are circulated to maintain a uniform dispersion state of the sample so that the sample passes through the glass cell 6 to reduce sampling errors.

On the other hand, the light applied to the measuring portion of the glass cell 6 is coherent light, and in this example, the laser light emitted from the laser tube 1 is used. The laser light emitted from the laser tube 1 is exchanged with an intermittent signal by the chopper 2 and travels, travels through the mirrors 3 and 4 and is converted into expanded parallel light by the beam expander 5 and projected on the measuring portion of the glass cell 6. It

The light projected onto the glass cell 6 hits the powder particles dispersed in the dispersion medium and causes a light diffraction phenomenon. The diffracted light is collected by the condenser lens 7 and forms an image on the diffraction ring of the Fraunhofer on the detector plate 8 arranged on the focal plane.

The radius R from the center of the optical axis of the diffractive ring is proportional to the light source wavelength λ and inversely proportional to the particle diameter (particle diameter) of dispersed particles. The intensity of the diffracted light at the predetermined radial position of the diffractive ring has a constant relationship with the amount of particles having a particle size corresponding to the radial position, as shown in the following Airy equation.

[0007]

[Equation 1]

I is the diffracted light intensity, J ₁ is the first-order Bessel function, k = 2π / λ, a is the radius of the particle, w = R / f (f is the focal length of the lens), and I ₀ is projected ( Laser) total energy of light, E is total energy reaching the sensor,
S is a cross-sectional area perpendicular to the optical axis of the projected light beam (such as a laser beam).

Therefore, the particle size distribution can be obtained by calculating the ratio of particles having a particle size corresponding to each radial position from the diffracted light intensity at each predetermined radial position of the diffraction ring.

Therefore, the detector plate 8 is provided with a sensor at a radial position corresponding to each particle size required for displaying as a particle size distribution, and each diffracted light output is detected.

An example of the result of measuring the particle size distribution as described above is shown in FIG. In the figure, the curve shows the cumulative volume distribution, the bar graph is the histograph, and the particle size is 16
It is classified and measured for each particle size range (channel).

The particle size distribution is measured based on the above principle, but it is a problem whether this optical diffraction type particle size distribution measuring device shows a correct particle size distribution. As the inspection method of the particle size distribution measurement device so far, there are a method of comparing with the measurement result by the measurement device based on other particle size distribution measurement principle and a method of making a certain particle size distribution sample and comparing with the measurement result by the same sample. There is.

The sieving method, the microscopic method, the sedimentation method, the electrical detection zone method, etc. are typical of the other particle size distribution measuring principles used in the former. The latter inspection method uses a sieve to adjust the particle size to a very narrow range.
A sample having a known particle size distribution, which is artificially prepared by mixing samples of the same substance of two or more species at a certain weight ratio, is used.

In the former case, however, the measurement results often do not match when the measurement principles are different, and it is not appropriate to determine one of the other measurement principles as the verification standard. In the latter case, there is an error in the particle size adjustment operation when preparing and mixing the powder sample, and the powder itself contains statistical and stochastic errors, and it is sufficient to use the error as a verification standard. It is difficult to make it small enough. Furthermore, what can be said for both is that inconvenient work is unavoidable in the verification of the measuring device.

Therefore, for example, it is possible to use a fixed sample in which a particle image is fixed on a transparent mask.

[0016]

[Problems to be Solved] However, it is difficult to prepare a fixed sample close to the actual dispersion medium state in liquid. Usually, when preparing a sample in which a particle image is fixed at a certain density, it is a simple and reliable method to arrange it in a square lattice, and to arrange it randomly like particles in an actual dispersion medium, On the contrary, it's difficult.

However, when the particle images of the same particle size are measured by the same particle size distribution measuring device under the same conditions, the result of the measurement shows that the particle images are regularly arranged like a square lattice and randomly arranged. Makes a difference. Therefore, a random array of particle images as a fixed sample is required to improve the accuracy of the test.

The present invention has been made in view of the above points, and an object thereof is to provide a method for producing a fixed sample for assay standard in which particle images are randomly arranged.

[0019]

In order to achieve the above object, the present invention creates an original drawing in which a predetermined number of particle images are randomly arranged on a square screen, and reduces and transfers the original drawing to a predetermined size. Create a square photoresist original image with a unit area, and lay the original images vertically and horizontally while randomly changing the vertical and horizontal positions to form a photomask, and print the photomask on a transparent substrate to form a particle image. Then, a method for producing a fixed sample for a verification standard of a particle size distribution measuring instrument for producing a fixed sample was used.

Based on a certain design, an original drawing in which particle images are randomly arranged is created, and an original image obtained by reducing and transferring the original image is arranged. In order to form a photomask by randomly laying it up and down while vertically and horizontally. Particle images are randomly arranged over the entire surface of the photomask.

Since the photomask is printed on a transparent substrate to form a particle image, the particle images of the manufactured fixed sample are randomly arranged without any regularity.

[0022]

EXAMPLE FIG. 1 and FIG. 2 show a fixed sample manufactured by the method of an example according to the present invention and a state in which the fixed sample is set in a particle size distribution measuring apparatus. The fixed sample 20 for the calibration standard of the particle size distribution measurement of the present example is a fixed sample in which predetermined particle images are arranged so that the cumulative volume distribution curve of the measured value becomes a straight line in accordance with the measurement range of the particle size distribution measuring instrument. (White spectrum).

The substrate 21 of the fixed sample 20 is a rectangular transparent glass plate in which the length of adjacent sides is a ratio of 1: 2.
In addition to glass, transparent acrylic and the like can be considered as the material. Half of the substrate 2 is left as a transparent portion, and a particle image of chromium or the like is arranged and deposited in the other half area.

The white spectrum of the fixed sample 20 is
The particle images are all circular and are all arranged on the same plane, the volume conversion concentration is 0.1%, and the cumulative volume distribution curve is from 0 to
It is designed to be a straight line at 192 μm.

Explaining the design of this white spectrum a little, under the above conditions, the particle size of 0 to 192 μm is divided into 16 channels corresponding to the measured channels of the particle size distribution measuring instrument, and the representative particle of each channel is divided. Determine the diameter,
Calculate the number of circular particle images of the same size per 2.8 mm square area (7.84 mm ² ). A flat space with a depth of 1 mm in the optical axis direction is used to replace the actual dispersion state with a two-dimensional distribution of the white spectrum.

Therefore, the area of 7.84 mm ² is the maximum particle size.
The area occupied by one particle image of 166.4 μm is the unit area when the particle image is laid out. From the above, particle size 0
The following table shows the design specifications of this white spectrum in which the cumulative volume distribution curve at 192 μm is a straight line.

[0027]

[Table 1]

Under such design specifications, an original drawing corresponding to a unit area of 2.8 mm square is first prepared. In the original drawing, each particle image having 16 kinds of particle diameters is drawn as randomly as possible by the corresponding number.

The random array is based on the particles in the actual dispersion medium, and the square lattice is a very exceptional array, and such a regular array is included in the random array in the present specification. I can't.

The original image is reduced and transferred to form a 2.8 mm square original image for photoresist. 39.2mm by laying this original picture vertically and horizontally in multiple vertical and horizontal positions
A four-way photomask is formed.

Therefore, in this photomask, particle images are randomly arranged over the entire surface of 39.2 mm square without any regularity. Based on this photomask, chrome particles are baked on half of the transparent glass substrate 21 to form a film.

As shown in FIG. 2, the fixed sample 20 manufactured in this manner is measured at a position between the beam expander 5 and the condenser lens 7 of the optical diffraction type particle size distribution measuring device, that is, the glass cell 6 described above. It is attached to the position where was placed and is used for verification and adjustment of the measuring instrument.

In the actual test, first, the transparent portion of the transparent glass substrate 21 is set downward, the laser beam is projected onto the transparent portion, and the light transmission amount as the background is measured beforehand. Then transparent glass substrate
21 is mounted upside down, set so that the laser beam hits the particle image forming portion (the state shown in FIG. 2), and measurement is performed.

The difference between the two outputs is the net output by the particle image, and the particle size distribution is obtained by analysis based on the above-mentioned principle.

If the particle size distribution measuring instrument shows the correct particle size distribution, when the fixed sample 20 (white spectrum) is set and measured, the cumulative volume distribution curve should be a straight line with a particle size of 0 to 192 μm. Is. Therefore fixed sample
By using 20, it is possible to verify whether or not the entire measurement range of the particle size distribution analyzer shows a correct distribution.

Also, the cumulative volume distribution curve can be made linear by adjusting the amplification factor of each amplifier for amplifying the sensor output arranged on the detector plate 8 for each channel, which facilitates the adjustment of the entire measurement range. It can be carried out.

The mounting metal fitting for mounting the transparent glass substrate 21 can also mount the glass cell 6, so that the glass cell 6 and the transparent glass substrate 21 can be easily attached and detached. Since the actual powder is not prepared and made each time, there is no error due to adjustment.

Although the fixed sample 20 is used for the calibration and adjustment of the light diffraction type particle size distribution measuring device in the above, the light scattering type particle size distribution measuring device can be similarly used.

On the other hand, focusing on one particle size instead of the white spectrum, a fixed sample in which single circular particle images of the same particle size are randomly arranged at a certain density is also conceivable. Such a fixed sample is suitable for performing accurate calibration and adjustment of a specific channel.

The white spectrum is for calibrating the entire measurement range with appropriate accuracy, and if attention is paid only to individual channels, it is difficult to adjust with high accuracy due to the influence of particle size particle images in the vicinity. Therefore, for a certain focused channel, highly accurate verification and adjustment can be performed by using a fixed sample having a single particle size.

In order to deal with actual particles having an extremely narrow particle size distribution, it is conceivable to use a fixed sample in which particle images having different particle sizes are mixed and arranged at a certain ratio.

The above various fixed specimens are extremely easy to handle,
No special measuring device is required for the calibration and adjustment work, and the operation is simple and convenient. Since the fixed sample hardly changes with time, it is possible to always perform a stable assay and easily detect the change with time due to deterioration of the laser tube of the main body of the measuring instrument.

By adopting a method of forming a particle image on a transparent substrate, the size of each particle image can be freely adjusted. In particular, large-sized particles are difficult to measure because they precipitate during actual measurement by dispersion in a liquid, and are not easily transported, but with this fixed sample, measurement at a stationary position can be reliably performed.

Since the shape of each particle, the number of particles per unit area, the layout on the substrate, etc. can be freely set,
It can correspond to the actual dispersion state in the liquid. It is also possible to investigate the comparative measurement of particles having different shapes (for example, needle shape, rectangular shape, circular shape, etc.), that is, the influence of shape.

When printing using an original image for a photoresist, it is possible to enlarge and reduce the size freely, so that it is possible to easily prepare fixed specimens having different particle sizes with one type of original image, mass production is possible, and the manufacturing cost can be reduced. it can.

Further, when a transparent substrate is baked using a new photomask in which a transparent portion and an opaque portion are reversed in the photomask to form a particle image, a transparent particle portion is formed in the opaque portion. However, since the same light diffraction phenomenon occurs when the particle size is the same, such a fixed sample can also be used as a standard for calibration and adjustment of the measuring device.

A film on which an image of particles is exposed can also be used as a fixed sample, and two types can be considered in which one of the substrate and the particle image is transparent and the other is opaque.

[0048]

According to the present invention, the original image obtained by reducing and transferring the original image in which the particle images are randomly arranged is arranged in different postures to form a photomask, and the photomask is printed to produce a fixed sample. It is possible to easily manufacture a fixed sample with high assay accuracy in which particle images are randomly arranged without any regularity.

Since the shape of each particle, the number of particles per unit area, the layout on the substrate, etc. can be set freely, a random array of special particle images that is convenient for the assay at the same time can be made to correspond to the actual dispersion state in liquid. Can be realized.

When a photomask is printed on a transparent substrate, it can be enlarged or reduced freely, so that fixed specimens of different particle sizes can be easily produced with one type of original image, mass production is possible, and the production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a fixed sample for assay standard manufactured by a method according to an embodiment of the present invention.

FIG. 2 is an explanatory view of relevant parts showing a state in which the fixed sample is set in a particle size distribution measuring instrument.

FIG. 3 is an explanatory diagram of an optical diffraction type particle size distribution measuring device.

FIG. 4 is a diagram showing an example of a result measured by the measuring device.

[Explanation of symbols]

1 ... Laser tube, 2 ... Chopper, 3, 4 ... Mirror, 5 ...
Beam expander, 6 ... Glass cell, 7 ... Condensing lens, 8 ... Detector plate, 9 ... Ultrasonic dispersion tank, 10
… Pump, 20… Fixed specimen, 21… Transparent glass substrate.

Claims (1)

[Claims] 1. An original drawing in which a predetermined number of particle images are randomly arranged on a square screen is created, and the original drawing is reduced and transferred to create a square photoresist original image having a predetermined unit area. A particle size distribution measuring device characterized in that a fixed sample is manufactured by forming a photomask by laying it vertically and horizontally while randomly changing the up, down, left, and right postures, and baking the photomask on a transparent substrate to form a particle image. Method for manufacturing fixed specimens for test standards.