JP2812991B2 - Particle counter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to, for example, a particle counter for detecting particles (particles) in a liquid passing through a tube.

[Prior art]

Conventionally, this type of particle counter illuminates the liquid flowing in a transparent tube, attaches a slit in the middle of the tube at one point perpendicular to the tube axis direction, and places a photomultiplier tube behind this strip to allow the particles to be placed. The reflected scattered light is detected.

[Problems to be solved by the invention]

The conventional particle counter described above has a problem that the detection sensitivity has to be reduced due to insufficient separation of the light reflected and scattered by the particle from the background light. The size of a particle is determined by the amount of reflected and scattered light. In general, the intensity of illumination light varies depending on the position of the particle in a tube, and therefore the amount of reflected and scattered light by the particle also varies depending on the position. For this reason, it is necessary to know the position of the particle, correct the light amount based on the position, and obtain the size of the particle from the corrected light amount. However, in the above-described conventional technology, it is not possible to obtain the position information of the particle. I got a point. Further, the conventional particle counter has a problem that when a plurality of particles overlap each other and pass through the slit when viewed from the direction of the photomultiplier tube, the plurality of particles cannot be distinguished. The present invention has been made in view of the above-described conventional problems, and has a particle counter capable of sufficiently separating light from a particle from background light to increase detection sensitivity and detect a small particle. The purpose is to provide. It is another object of the present invention to provide a particle counter capable of obtaining particle position information and correcting the position of the detection light to determine the size of the particle. It is still another object of the present invention to provide a particle counter capable of discriminating, even when a plurality of particles overlap and pass simultaneously when viewed from one direction.

[Means for Solving the Problems]

The present invention relates to a one-dimensional optical fiber for start detection, a one-dimensional optical fiber for X-axis detection, and a one-dimensional optical fiber for X-axis detection, which are irradiated with light and move in one direction with respect to particles moving in one direction. One-dimensional optical fiber for end detection, and an X-axis lens arranged between the three sets of optical fibers and the flow path of the particles, and forming an image of the particles on the light receiving end faces of the three sets of optical fibers. A one-dimensional optical fiber for Y-axis detection arranged at the same moving direction position as the one-dimensional optical fiber for X-axis detection, and a one-dimensional optical fiber for Y-axis detection and the flow path of the particles. A Y-axis lens for forming an image of the particles on the light receiving end face of the one-dimensional optical fiber for Y-axis detection, and a photodetector for converting an optical signal extracted from the one-dimensional optical fiber into an electric signal. And a signal processing circuit for processing a signal from the photodetector to detect the position of the particle in the X and Y directions, wherein the four sets of one-dimensional optical fibers each include the particle. In a plane perpendicular to the moving direction of the moving direction, the light receiving axis is configured by bundling a plurality of optical fibers positioned in a direction perpendicular to the moving direction in a one-dimensional direction, and the one-dimensional optical fiber for Y-axis detection, The light receiving axis is arranged in a direction orthogonal to the one-dimensional optical fiber for X-axis detection, and the signal processing circuit detects an optical signal from a particle corresponding to the optical signal detected by the one-dimensional optical fiber for start detection for end detection. The above object is achieved by a particle counter characterized in that a detection signal of the particle is processed until a one-dimensional optical fiber detects the particle. Further, the above-mentioned object is achieved as a one-dimensional photodetector. Further, the above-mentioned object is attained by allowing the one-dimensional photodetector to have its light receiving channel divided into four parts, each of which is connected to the output terminals of the four sets of one-dimensional optical fibers. Further, two to four photodetectors are provided, and each photodetector is connected to an output terminal of at least one set of one-dimensional optical fibers of the four sets, and the above-mentioned object is achieved. To achieve. Further, the above object is achieved by using the plurality of photodetectors as a one-dimensional photodetector. Furthermore, a photodetector connected to at least one of the one-dimensional optical fiber for start detection and the one-dimensional optical fiber for end detection is a 0-dimensional photodetector for detecting the presence or absence of light at one point, and the other The above object is achieved by using the photodetector as one or more one-dimensional photodetectors.

[Action]

In the present invention, one-dimensional optical fibers obtained by bundling optical fibers one-dimensionally in one direction are arranged adjacent to each other in the moving direction of the particles for start detection, X-axis detection, and end detection. One-dimensional optical fiber for Y-axis detection,
The one-dimensional optical fiber for X-axis detection is arranged at the same position as the one-dimensional optical fiber for X-axis detection and in a direction different by 90 °, between the one-dimensional optical fiber for start detection and the one-dimensional optical fiber for end detection. Only the particles passing through the front surface of the fiber and the one-dimensional optical fiber for Y-axis detection are detected together with their X and Y position information. At this time, the image of the particles is imaged by the imaging lens, and this is separated and detected for each channel of the optical fiber, so the separation performance of the reflected scattered light by the particles from the background light is good, and even small particles can be detected. it can.

【Example】

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, as shown in FIG.
The inside is a particle counter that illuminates a liquid 12 flowing from left to right in the figure from the right side of the figure with a light source (not shown) and detects particles 1 in the liquid 12. Each of the particle counters is provided on the outside of the glass tube 10 in a plane orthogonal to the tube axis of the glass tube 10.
One-dimensional optical fiber 16, X for start detection, composed of one-dimensional bundle of optical fibers (250 channels)
The one-dimensional optical fiber 18 for axis detection and the one-dimensional optical fiber 20 for end detection are sequentially adjacent to each other in the tube axis direction from left to right in the figure, and the light receiving axes of these optical fibers are set to the tube of the glass tube 10. Arranged perpendicular to the axis.
In the same orthogonal plane at the same tube axis position as the one-dimensional optical fiber 18 for axis detection, the light receiving axis is the one-dimensional optical fiber for X-axis detection.
A one-dimensional optical fiber 22 for Y-axis detection in a direction orthogonal to 18 is arranged, and these four sets of one-dimensional optical fibers 16 to 22 are connected to a light receiving channel of a one-dimensional photodetector 24. The one-dimensional photodetector 24 is for detecting a one-dimensional intensity distribution of light, for example, an image intensifier for enhancing weak light to a sensitivity region of a semiconductor optical sensor, and an electric signal for enhancing the enhanced light. It is composed of a self-scanning linear image sensor PCD for converting a signal corresponding to a one-dimensional optical image incident on an image intensifier as a time-series electrical signal output. This one-dimensional photodetector has 1,000 channels, the output terminals of the one-dimensional optical fiber 16 for the start detector are connected to the first to 250th channels, and the X-axis detection is connected to the 251st to 500th channels. The output end of the one-dimensional optical fiber 18 is connected, the output end of the one-dimensional optical fiber 22 for Y-axis detection is connected to the 501st to 750th channels, and the end detection is connected to the 75th to 1000th channels. The output end of the one-dimensional optical fiber 20 is connected. As described above, this one-dimensional photodetector outputs a signal corresponding to a one-dimensional optical image in a time-series output, and a signal processing circuit 26 that processes the output signal includes a start determination unit.
28, an end determiner 30, and a data memory 32. The start determination unit 28 includes a one-dimensional photodetector 24.
When a detection signal is output to any one of the channels 1 to 250, a start signal is generated using the detection signal and the data memory 32 is operated. The data memory 32 scans all of the 251st to 750th channels in the one-dimensional photodetector 24 corresponding to the X-axis and Y-axis detection one-dimensional optical fibers 18 and 22 at a speed of several milliseconds, and every scan. It stores all outputs. The end determiner 30 is a one-dimensional optical fiber for end detection.
When an electric signal is output to any of the 751 to 1000th channels in the one-dimensional photodetector 24 corresponding to 20, an end signal is sent to the data memory 32, and the data memory 32 is stopped, and at the same time, the external computer 34 To output a signal notifying the end of data acquisition. The one-dimensional optical fibers 16, 18, and 20 for the start detection, the X-axis detection, and the end detection are provided between the glass tube 10 and the image of the particles 14 moving in the glass tube 10. An X-axis lens 36 imaged at the input terminals 18 and 20 is coaxially arranged with these one-dimensional optical fibers. Similarly, between the glass tube 10 and the input end of the one-dimensional optical fiber 22 for Y-axis detection, a Y-axis lens 38 for forming an image of the particle 14 on the input end of the optical fiber is coaxially arranged with the optical half-fiber. Are located. Next, the operation of the particle counter according to the above embodiment will be described. The liquid 12 flowing in the glass tube 10 is irradiated from the right direction in FIG. 1, that is, from the direction opposite to the flow of the liquid 12. The particles 14 in the liquid 12 move rightward in the drawing together with the flow of the liquid 12, and the front faces of the one-dimensional optical fiber 16 for detecting start, the optical fiber 18 for detecting X-axis, and the one-dimensional optical fiber 20 for detecting end. Sequentially. This particle 14 first crosses the one-dimensional optical fiber 16 for start detection, so that the particle 14
The illumination light reflected and scattered by is captured by the one-dimensional optical fiber 16 for start detection, and the first to
The signal is input to one of the 250 channels, and this is converted into an electric signal, which is input to the start determination unit 28. The start determiner generates a start signal in response to the signal input, whereby the data memory 32 is operated. Next, the particle 14 passes in front of the one-dimensional optical fiber 18 for X-axis detection and the one-dimensional optical fiber 22 for Y-axis detection. Therefore, the scattered light reflected by the particle 14 is reflected by the one-dimensional photodetector 24 corresponding to these optical fibers by the 251-
The signal is input to both the 00 and 501 to 750 channels and converted into an electric signal. The activated data memory 32 stores signals obtained by scanning all of the 251st to 750th channels at a speed of several milliseconds, and stores all outputs for each scan. The particles 14 move further in the glass tube 10 and pass over the front surface of the one-dimensional optical fiber 20 for end detection. At this time, an electric signal is generated in any of the 751 to 1000th channels in the corresponding one-dimensional photodetector 24, and this output signal is input to the end determiner 30, and the end determiner 30 converts the end signal into data. The data is sent to the memory 32, and the data memory 32 is stopped, and at the same time, a signal is sent to the external computer 34 to notify the end of the data acquisition. The external computer 34 takes in the data in the data memory 32 while the data memory 32 is operating, selects valid data, finds the position of the particle 14 in the X and Y directions,
A position correction calculation based on these XY signals is performed on the particle signal size to determine the particle size,
Do the processing. According to this embodiment, the image of particle 14 is X
Since an image is formed by the axis lens 36 and the Y-axis lens 38 and separated and detected for each channel of the optical fiber, the scattered light reflected by the particles 14 can be separated and detected efficiently from the background light. Therefore, even small particles that could not be detected conventionally can be detected. Furthermore, when the particle 14 passes, the one-dimensional optical fiber 16 for start detection and the one-dimensional optical fiber 20 for end detection allow the one-dimensional optical fibers 18 and 22 for X-axis and Y-axis detection only when passing through the front surface. Effective data can be effectively captured. Further, for example, even if a plurality of particles pass simultaneously in a superimposed manner when viewed from the X-axis direction, since the observation is also performed from the Y-axis direction by the one-dimensional optical fiber 22 for Y-axis detection, X, X A plurality of particles can be determined based on the difference between the Y position information and the signal magnitude. A plurality of particles 14 having the same X-axis and Y-axis direction positions between the detection position of the one-dimensional optical fiber 16 for start detection and the detection position of the one-dimensional optical fiber 20 for end detection in the flow path of the liquid 12. Are present at the same time, it is impossible to discriminate them, resulting in a measurement error. In practice, however, the distance between the two detection positions in the moving direction of the particle 14 is as shown in FIG. , Three rows of one-dimensional optical fibers, that is, about three optical fibers (including the protective cover), which is short, so that the probability of occurrence of the measurement error as described above is extremely low. Further, this kind of particle counter is for detecting foreign matter which should not be present in a highly pure liquid, for example, foreign matter rarely present in pure water used for semiconductor production. It is more rare that a plurality of foreign substances having the same position in both axial directions are present in a row, and there is no problem in measurement. Further, although the one-dimensional photodetector 24 is usually very expensive, the cost of the one-dimensional photodetector 24 can be reduced because the channel of the expensive one-dimensional photodetector 24 is divided into four parts. There is. In the above-described embodiment, the 1000 channels of the one-dimensional photodetector 24 are divided into four and used, but the present invention is not limited to this. A one-dimensional photodetector may be connected.
Also, the number of channels is not limited, and less than 250 or more than 250 channels may be applied to one set of optical fibers. Further, as the one-dimensional optical fiber 16 for the start detector and the one-dimensional optical fiber 20 for the end detector, a zero-dimensional detector which is a normal photomultiplier may be used. In other words, any device can be used as long as it can detect the presence or absence of light input at any one (one point) of the plurality of optical fibers constituting the bundle of one-dimensional optical fibers. Further, in the above embodiment, the particles 14 contained in the liquid 12 flowing in one direction in the glass tube 10 are detected, but the present invention generally applies particles moving in one direction to light. This is applied to the case of irradiating and detecting this.

【The invention's effect】

Since the present invention is configured as described above, it has an excellent effect that particles moving in one direction can be efficiently separated and detected from the background light, and position data in the X and Y axis directions can be obtained at the same time. Have.

[Brief description of the drawings]

FIG. 1 is a sectional view including a partial block diagram showing an embodiment of a particle counter according to the present invention. 10 ... glass tube, 12 ... liquid, 14 ... particle, 16 ... one-dimensional optical fiber for start detection, 18 ... one-dimensional optical fiber for X-axis detection, 20 ... one-dimensional optical fiber for end detection, 22: One-dimensional optical fiber for Y-axis detection, 24: One-dimensional photodetector, 26: Signal processing circuit, 28: Start determiner, 30: End determiner, 32: Data memory, 34 ... ... External computer, 36 ... X-axis lens, 38 ... Y-axis lens.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06M 11/00 G06M 7/00

Claims (6)

(57) [Claims] 1. A one-dimensional optical fiber for start detection, a one-dimensional optical fiber for X-axis detection, and a one-dimensional optical fiber for X-axis detection, which are sequentially arranged from the upstream in the moving direction to the downstream in the moving direction with respect to particles illuminated by light and moving in one direction. One-dimensional optical fiber for end detection, and an X-axis lens arranged between the three sets of optical fibers and the flow path of the particles, and forming an image of the particles on the light receiving end faces of the three sets of optical fibers. A one-dimensional optical fiber for Y-axis detection arranged at the same moving direction position as the one-dimensional optical fiber for X-axis detection, and a one-dimensional optical fiber for Y-axis detection and the flow path of the particles. A Y-axis lens for forming an image of the particles on the light receiving end face of the one-dimensional optical fiber for Y-axis detection, and a photodetector for converting an optical signal extracted from the one-dimensional optical fiber into an electric signal. And a signal processing circuit for processing a signal from the photodetector to detect the position of the particle in the X and Y directions, wherein the four sets of one-dimensional optical fibers each include the particle. In a plane perpendicular to the moving direction of the moving direction, the light receiving axis is configured by bundling a plurality of optical fibers positioned in a direction perpendicular to the moving direction in a one-dimensional direction, and the one-dimensional optical fiber for Y-axis detection, The light receiving axis is disposed in a direction orthogonal to the X-axis detecting one-dimensional optical fiber, and the signal processing circuit includes a primary signal for detecting an optical signal end from a particle corresponding to the optical signal detected by the one-dimensional optical fiber for starting detection. A particle counter which processes a detection signal corresponding to the particle until the original optical fiber detects the particle. 2. A particle counter according to claim 1, wherein said photodetector is a one-dimensional photodetector. 3. The one-dimensional photodetector according to claim 2, wherein the light-receiving channel of the one-dimensional photodetector is divided into four parts, each of which is connected to the output terminals of the four sets of one-dimensional optical fibers. Kuru counter. 4. The apparatus according to claim 1, wherein two to four photodetectors are provided, and each photodetector is connected to an output end of at least one of the four sets of one-dimensional optical fibers. A particle counter characterized by: 5. The particle counter according to claim 4, wherein said plurality of photodetectors are one-dimensional photodetectors. 6. The zero-dimensional optical detector according to claim 4, wherein the photodetector connected to at least one of the one-dimensional optical fiber for start detection and the one-dimensional optical fiber for end detection detects the presence or absence of light at one point. A particle counter, which is a photodetector, wherein the other photodetectors are one or more one-dimensional photodetectors.