Optics: measuring and testing – For size of particles – By particle light scattering
Reexamination Certificate
2001-05-16
2004-05-25
Lee, Michael G. (Department: 2876)
Optics: measuring and testing
For size of particles
By particle light scattering
C356S337000, C356S335000, C356S343000, C356S338000
Reexamination Certificate
active
06741350
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a particle (grain) size measuring apparatus, which detects a diffraction/scattered light or dynamic light scattering by irradiating a laser beam onto a particle group such as a dispersing powder sample or the like, and measures a particle size distribution of the particle group on the basis of a scattered light intensity signal or the like obtained by the detection and more particularly provides an automatic validation and instruction mode.
2. Description of the Prior Art
Conventionally, a particle size distribution measuring apparatus using a light diffraction phenomenon or scattering phenomenon by a particle has calculated a particle size distribution of a sample particle in the following manner. More specifically, the above apparatus measures intensity distribution of a diffraction light or a scattered light, that is, a relation between a diffraction angle or scattering angle and a light intensity, and then, carries out arithmetic processing based on a Frauunhofer diffraction theory or Mie scattering theory with respect to the measured result. In the above manner, the above apparatus has calculated the particle size distribution of a sample particle. The above particle size distribution measuring apparatus has been used for research and development of raw materials in most mining and industrial fields such as the cement or the ceramic industry, and in a new material field mainly using ceramics.
For example, to give an example of the above apparatus, there is a particle size distribution measuring apparatus disclosed in Japanese Examined Patent publication No. 6-43950.
FIG. 16
is a view schematically showing a construction of the particle size distribution measuring apparatus disclosed in this Publication. In
FIG. 16
, a reference numeral
10
denotes a cell comprising a transparent container for receiving a sample solution
11
dispersing a particle group of the measuring object in a proper dispersion medium, and a reference numeral
12
denotes a laser beam source provided on one side (backward side) of the cell
10
. A parallel laser beam
13
emitted from the laser beam source
12
is enlarged by a beam expander (not shown), and then, is irradiated to the cell
10
in an enlarged state.
In
FIG. 16
, a reference numeral
14
denotes a condenser lens provided on the other side (forward side) of the cell
10
, and a ring detector
15
is arranged at a focal position of the condenser lens
14
. The ring detector
15
is constructed in a manner that a plurality of photo sensors having mutually different radii and a ring or semi-ring light receiving plane is arrayed concentrically around an optical axis of the condenser lens
14
. Further, the ring detector
15
receives light scattered/diffracted at a relatively small angle to the optical axis of the laser beam
13
diffracted or scattered by particles in the cell
10
for each scattering angle, and then, measures their light intensity.
Moreover, a wide angle scattered light photo detector group
16
is provided at the vicinity of the cell
10
. The wide angle scattered light photo detector group
16
individually detects light scattered/diffracted at a relatively large angle to the optical axis of the laser beam
13
diffracted/scattered by the particles in the cell
10
for each scattered light. Further, the wide angle scattered light photo detector group
16
is composed of a plurality of photo sensors
17
to
22
provided at an angle different from the condenser lens
14
and the ring detector
15
. Thus, the photo detector group
16
can detect a wide angle scattered light exceeding a predetermined angle by the particles in the cell
10
in accordance with each oriented angle. In the photo detector group
16
, the photo sensors
17
to
20
detect a forward scattering light, the photo sensor
21
detects a side scattering light, and the photo sensor
22
detects a backscattering light.
A reference numeral
23
denotes a pre-amplifier for amplifying an output of the photo sensors constituting the ring detector
15
, and a reference numeral
24
denotes a pre-amplifier for amplifying each output of the forward scattering light photo sensors
17
to
20
. Further, a reference numeral
25
denotes a pre-amplifier for amplifying each output of the side scattering light photo sensor
21
and the backscattering light photo sensor
22
. A reference numeral
26
denotes a multiplexer for successively capturing each output of the pre-amplifier groups
23
to
25
and transmitting it to an A-D converter
27
, and a reference numeral
28
denotes a computer which is used as an arithmetic processor for inputting an output from the A-D converter
27
. The computer
28
stores a program for processing each output converted into a digital signal (digital data relative to light intensity) of the ring detector
15
and the photo sensors
13
to
22
on the basis of a Frauunhofer diffraction theory or Mie scattering theory, and obtaining a particle size distribution in a particle group.
In the above particle size distribution measuring apparatus, in a state that the sample solution
11
is received in the cell
10
, when the laser beam
13
is irradiated from the laser beam source
12
to the sample cell
10
, the laser beam
13
is diffracted or scattered by the particles in the cell
10
. Of the diffracted light or scattered light, a light having a relatively small scattering angle is imaged on the ring detector
15
by the condenser lens
14
. In this case, the photo sensor arranged on the outer side receives a light having a larger scattering angle; on the other hand, the photo sensor arranged on the inner side receives a light having a smaller scattering angle. Therefore, a light intensity detected by an outer-side photo sensor means a quantity of particles having smaller particle diameter (particle size); on the other hand, a light intensity detected by the inner-side photo sensor means a quantity of sample particles having larger particle diameter. The light intensity detected by each of these photo sensors is converted into an analog electric signal, and further, is inputted to the multiplexer
26
via the pre-amplifier
23
.
On the other hand, of the laser beam
13
diffracted light or scattered by the particles, a light, which is not converged by the condenser lens
14
and has a relatively large scattering angle, is detected by the photo sensors
17
to
22
, and then, its light intensity is measured. In this case, the forward scattering light photo sensors
17
to
20
, the side scattering light photo sensor
21
and the backscattering light photo sensor
22
successively detect a scattering light from a particle having a small particle size. The light intensity detected by each of these photo sensors
17
to
22
is converted into an analog electric signal, and further, is inputted to the multiplexer
26
via the pre-amplifier groups
24
and
25
.
The multiplexer
26
captures measurement data from the ring detector
15
and the photo sensors
17
to
22
, that is, an analog electrical signal in a predetermined order. The analog electric signal captured by the multiplexer
26
is made into a serial signal, then, is converted by the A-D converter
27
into a digital signal in succession, and thereafter, is inputted to the computer
28
.
Subsequently, the computer
28
processes the light intensity data for each scattering angle obtained by each sensor of the ring detector
15
and the photo sensors
17
to
22
on the basis of a Frauunhofer diffraction theory or Mie a scattering theory.
As described above, in the above particle size distribution measuring apparatus, a light intensity distribution of scattering light having a substantially larger particle size is measured by the ring detector
15
and a light intensity distribution of wide-angle scattering light having a mainly smaller particle size is measured by the photo sensors
17
to
22
. Further, the output of these ring detector
15
and photo sensors
17
to
22
is processed
Ikeda Hideyuki
Yoshioka Seiichiro
Horiba Ltd.
Kim Ahshik
Lee Michael G.
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