JP4627022B2 - Photometric analyzer - Google Patents

Description

  The present invention relates to a photometric analyzer that measures the absorbance and the like of organic substances contained in industrial wastewater, rivers, etc. In particular, the cell length can be changed easily and quickly, and continuous measurement can be performed without using a synchronization circuit. It relates to a photometric analyzer that can be used.

  With regard to this photometric analyzer, as shown in Patent Document 1, the present applicant arranges two cylindrical bodies in a measurement sample so as to be spaced apart from each other in parallel, and rotates two cylinders by rotating at least one cylindrical body. The present invention has been invented to measure the absorbance of the measurement sample interposed between the opposing surfaces by periodically changing the distance between the opposing surfaces of the cylindrical body. The present invention measures the absorbance of a measurement sample by comparing the light intensity signals of these two points using the shortest distance and the longest distance between the opposing surfaces.

However, in such a case, since the variable width between the opposing surfaces, that is, the difference between the longest distance and the shortest distance is constant, the measurement range of the photometric analyzer is uniquely determined. There is a problem that sufficient measurement results cannot be obtained depending on the concentration of the measurement sample having a low concentration to a high concentration. Conventionally, in order to solve the problem, a plurality of types of apparatuses having physically different variable widths must be prepared.
JP-A-56-10233

  Therefore, the present invention has been made to solve the above-mentioned problems all at once, and it is possible to measure from a low-concentration measurement sample to a high-concentration measurement sample by expanding the measurement range without any physical changes. Providing a photometric analyzer that can be performed is the main intended task.

That is, the photometric analyzer according to the present invention, the cylindrical body having a light source inside, and the cylindrical body having a photodetector for detecting light from the light source is arranged in the measurement sample apart from each other, A photometric analyzer for analyzing a measurement sample interposed between the opposing surfaces by rotating at least one cylindrical member to periodically expand and contract the distance between the opposing surfaces of the two cylindrical members, The light detection between a phase detection unit that detects a phase of rotation of the cylindrical body, and a phase when the distance between the opposing surfaces is minimum and a phase when the distance between the opposing surfaces is maximum a phase setting section for changeably setting a plurality of phase for sampling the light intensity signal from the vessel, based on the phase detection signal from the phase detector, the light intensity at a plurality of phases that have been set by the phase setting unit A signal receiving unit for receiving a signal and the signal receiving unit; Characterized in that the part is provided with a comparative analysis section for analyzing the measurement target by comparing the light intensity signals at each phase of the reception. Here, between the phase when the distance between the opposing surfaces is minimum and the phase when the distance between the opposing surfaces is maximum is the phase when the distance between the opposing surfaces is minimum, and the opposing The phase when the distance between the surfaces is maximum is also included in the range.

  If this is the case, the light intensity signal from the photodetector is sampled between the phase when the distance between the opposing surfaces is minimum and the phase when the distance between the opposing surfaces is maximum. Since the phase can be set to be changeable, it is possible to provide a photometric analyzer that can widen the measurement range without physically changing it, and can measure from low-concentration measurement samples to high-concentration measurement samples. it can.

  As a specific embodiment, the cylindrical body is rotated by a stepping motor, and the phase detector uses a pulse train input signal to the stepping motor to rotate the cylindrical body. It is preferable to detect the phase.

  In such a case, since the stepping motor is used, the rotational speed can be made accurate without being affected by the power supply frequency unlike the induction motor, and the measurement accuracy can be ensured.

  In addition to the stepping motor, another motor capable of controlling the rotation speed may be used.

  In addition, it is conceivable that the phase detection unit detects a phase of rotation of the cylindrical body using a signal from an encoder.

Thus, according to the present invention, the light intensity signal from the photodetector is sampled between the phase when the distance between the opposing surfaces is minimum and the phase when the distance between the opposing surfaces is maximum. Providing a photometric analyzer that can expand the measurement range without making a physical change and can measure from low to high concentration measurement samples. Can do.

  <First Embodiment>

  Next, a first embodiment of the photometric analyzer of the present invention will be described with reference to the drawings.

  A photometric analyzer 1 according to the present embodiment is for measuring organic pollutants in a measurement sample (drainage) W. As shown in FIG. 1, a first tubular body having a light source 2 therein. 21, a second cylindrical body 31 having a photodetector 3 for detecting light from the light source 2 inside, and these two cylindrical bodies 21, 31 are arranged in parallel and spaced apart, and the measurement sample W is The analysis cage 4 to be accommodated, the drive unit 5 that periodically expands and contracts the distance L between the opposing surfaces 21A and 31A of the two cylindrical bodies 21 and 31 in the analysis tank 4, and the light intensity signal from the photodetector 3 And an information processing device 6 that performs a predetermined calculation and analyzes the measurement sample W.

  Each part will be described.

  The first cylindrical body 21 and the second cylindrical body 31 have a bottomed cylindrical shape that is spaced apart in parallel in the measurement sample W. The side peripheral wall is formed of a measurement wavelength transmission material, and in this embodiment, quartz having a high transmittance is used.

  In the first cylindrical body 21, a light source 2 is provided at a position eccentric from the central axis of the cylindrical body 21, and in this embodiment, a low-pressure mercury discharge tube is used as the light source 2. In the second cylindrical body 31, two photodetectors 3a and 3b are arranged along the central axis at positions eccentric from the central axis of the cylindrical body 31, and in this embodiment, the photodetector Silicon photodiodes are used as 3a and 3b.

  In order to use the photodetectors 3a and 3b for ultraviolet detection and visible light detection, an ultraviolet detection interference filter (254 nm) 7a and visible light are respectively provided in front of the light detectors 2 on the photodetectors 3a and 3b. A detection interference filter (546 nm) 7b is provided.

  A cleaning mechanism for cleaning the outer peripheral surface is provided outside the first cylindrical body 21 and the second cylindrical body 31. This cleaning mechanism includes wipers 22 and 32 that are in sliding contact with the outer peripheral surfaces of the first and second cylindrical bodies opposite to the opposed surfaces 21A and 31A, and the wipers 22 and 32 are connected to the cylindrical bodies 21 and 31. It is composed of wiper mounting plates 221 and 321 that reciprocate following the eccentric rotation.

  The drive unit 5 includes a motor 51 for rotationally driving the cylindrical bodies 21, 31, a first rotation shaft 52 that extends from the upper end of the first cylindrical body 21 and is on the concentric axis of the light source 2, The rotation of the motor 51 is transmitted to the two cylindrical bodies 21 and 31, extending from the upper end of the second cylindrical body 31 and on the second rotating shaft 53 on the concentric shaft of the photodetectors 3a and 3b. The first cylindrical body 21 includes a gear 54 that rotates eccentrically about a rotation axis that is eccentric from the central axis, and a second gear 31 that rotates eccentrically about the rotation axis that is eccentric from the central axis. . In this embodiment, the light source 2 is arranged on the rotation axis of the first cylindrical body 21, is eccentrically rotated around the light source 2, and the photodetectors 3 a and 3 b are arranged on the rotation axis of the second cylindrical body. Are arranged and rotated eccentrically around the photodetectors 3a and 3b.

By driving the motor 51, as shown in FIG. 2, the first cylindrical body 21 and the second cylindrical body 31 rotate eccentrically, and the light intensity signal detected by the photodetectors 3a and 3b and the opposing surface are detected. The distance between 21A and 31A changes periodically. The motor 51 is a stepping motor that rotates once in 48 steps. Then, the rotational position (phase θ ₅₁ ) of the stepping motor 51, that is, the distance L between the opposing surfaces 21A, 31A of the first cylindrical body 21 and the second cylindrical body 31, and the light received by the photodetectors 3a, 3b. Since it is necessary to synchronize the sampling of the intensity signal, the photointerrupter 8 serving as the origin detection unit is provided on the second rotating shaft 53. Note that the photo interrupter 8 may be provided on the first rotation shaft 52.

  The information processing apparatus 6 controls the stepping motor 51, receives light intensity signals from the photodetectors 3a and 3b, performs a predetermined calculation, and analyzes the measurement sample W. As shown in FIG. 3, the device configuration is a general purpose or dedicated computer comprising a CPU 601, an internal memory 602, an input / output interface 603, an AD converter 604, etc., and a program stored in a predetermined area of the internal memory 602. As shown in FIG. 4, the CPU 601 and its peripheral devices are operated based on the motor control unit 61, the phase detection unit 62, the phase setting unit 63, the signal reception unit 64, the distance calculation unit 65, and the comparison analysis unit. 66 and so on.

  Below, each part 61-66 is demonstrated.

  The motor control unit 61 rotates the stepping motor 51 by outputting a pulse train signal to the stepping motor 51. Further, an origin detection signal is received from the origin detection unit 8 to control the rotation phase of the stepping motor 51 so that no rotation error occurs. Further, the pulse train signal output to the stepping motor 51 is also output to the phase detector 62.

The phase detector 62 detects the phases θ ₂₁ and θ ₃₁ of the first cylindrical body 21 and the second cylindrical body 31. In the present embodiment, since the first cylindrical member 21 and the second cylindrical body 31 by rotation of the stepping motor 51 rotates in conjunction with the gear 54, the Knowing the phase theta ₅₁ of rotation of the stepping motor 51 The rotational phases θ ₂₁ and θ ₃₁ of the first cylindrical body 21 and the second cylindrical body 31 can be detected. Therefore, the phase detector 62 receives a pulse train signal from the motor controller 61 to the stepping motor ₅₁ and detects the phase θ ₅₁ of the stepping motor 51 based on the pulse train signal.

The phase setting unit 63 is configured so that the phase θ ₂₁ , θ ₃₁ and the opposing surfaces 21A, 31A when the distance L between the opposing surfaces 21A, 31A between the first cylindrical body 21 and the second cylindrical body 31 is the minimum. A plurality of phases for sampling the light intensity signal from the photodetector, that is, a plurality of sampling points, phase θ _S , can be changed between the phases θ ₂₁ and θ ₃₁ when the distance L is maximum. The setting signal is output to the signal receiving unit 64.

Specifically, in the present embodiment, as shown in FIG. 5, the rotational phase θ ₅₁ of the stepping motor 51 when the distance L between the opposing surfaces 21A and 31A is minimum and the distance L between the opposing surfaces 21A and 31A. The phase θ _S that is a plurality of (two in FIG. 5) sampling points is set so as to be changeable between the rotation phase θ ₅₁ of the stepping motor 51 when the maximum value is. The counter surface 21A, the phase theta ₅₁ and the facing surface 21A when the distance L between 31A is minimized, and between the phase theta ₅₁ when the distance L between 31A is maximum, the facing surface 21A, phase theta ₅₁ when the distance L between 31A is _minimized, and also the phase theta ₅₁ when facing surface 21A, the distance L between 31A becomes maximum is intended to include within their scope.

Here, the phase θ _S that is a sampling point is the phase θ ₂₁ , θ ₃₁ of rotation of the cylindrical bodies 21, 31 when the signal receiving unit 64 described later receives a light intensity signal from the photodetectors 3 a, 3 b. In the embodiment, it is the phase θ ₅₁ ) of the stepping motor 51. The phase setting unit 63 may be configured to set the phase θ _S that is a plurality of sampling points based on an input signal from the operator.

Further, it is also possible to obtain a density by calculation for the phase θ _S which is a plurality of other sampling points that can be selected, and to process them in a composite manner.

When the phase θ ₅₁ of the stepping motor 51 indicated by the phase detection signal from the phase detection unit 62 is the same as each phase θ _S set by the phase setting unit 63, the signal receiving unit 64 detects the photodetectors 3a and 3b. Is received, and the light intensity signal is output to the comparative analysis unit 66.

The distance calculation unit 65 calculates the distance L between the opposing surfaces 21A and 31A of the cylindrical bodies 21 and 31 at the two phases θ _S set by the phase setting unit 63 based on the phase θ _S.

  The comparative analysis unit 66 receives the light intensity signal received by the signal receiving unit 64 from the photodetector 3a for ultraviolet detection, and further calculates the ultraviolet absorbance of the measurement sample W based on the distance L calculated by the distance calculating unit 65. Is to be calculated. Further, the signal reception unit 64 receives the light intensity signal received from the visible light detection photodetector 3b, and further calculates the visible light absorbance of the measurement sample W based on the distance L calculated by the distance calculation unit. It is. Furthermore, COD (chemical oxygen demand) is calculated using the calculated ultraviolet absorbance and visible light absorbance.

  A specific method for calculating absorbance will be described below.

  In general, the relationship between the absorbance of the measurement sample W, the amount of light emitted from the light source 2, and the amount of light received by the photodetectors 3a and 3b is

(Equation 1)
LOG [Io / Ic] = Ac * Cc * L = Absorbance (Abs.)

It becomes. Here, I 2 _O is the light emission amount of the light source 2 and is equal to the light reception amount when there is no light absorption. Ic is the amount of light received by the photodetectors 3a and 3b. A _C is a coefficient of the distance L between the opposed surfaces 21A, 31A, opposed surface 21A, the distance L between 31A determines if Kimare. C _C is the concentration of the absorbing substance in the measurement sample W. L is the distance between the opposing surfaces 21A, 31A of the cylindrical bodies 21, 31.

In the photometric analyzer according to the present embodiment, since the distance L between the opposed surfaces 21A and 31A is periodically changed, the state at a certain phase θ ₅₁ (the phase θ _S which is a sampling point) is expressed using n. When,

(Equation 2)
LOG [Io / Ic (n)] = Ac * Cc * L (n) = Absorbance (Abs.)

  It becomes. Here, even if the distance L between the opposing surfaces 21A and 31A changes, the intensity of the light source 2, the concentration of the measurement sample W, and the coefficient of the distance L between the opposing surfaces 21A and 31A do not change.

  Next, when Ic (1) and Ic (2) are measured when n = 1 and n = 2,

(Equation 3)
LOGIc (2) −LOGIc (1) = Ac * C _C * (L (1) −L (2))

It becomes. According to this result, it is understood that the I 2 _O term disappears, and the absorbance has no relation to the light emission amount of the light source 2.

Therefore, the absorbance (A _C * C _C * 10) when the distance L between the opposing surfaces 21A and 31A is 10 mm, for example, is

(Equation 4)
_{A C * C C * 10 =} 10 * (LOGI C (2) -LOGI C (1)) / (L (1) -L (2)) ··· ( Equation 1)

It becomes. That is, the absorbance when the distance L between the opposing surfaces 21A and 31A is 10 mm depends on the distance L between the opposing surfaces 21A and 31A at the phase θ _S that is two sampling points and the received light intensity of the photodetectors 3a and 3b. Can be measured.

  Next, the operation of the photometric analyzer 1 of this embodiment will be described.

  The measurement sample W is accommodated in the analysis tank, and the first cylindrical body 21 and the second cylindrical body 31 are immersed in the measurement sample W.

And by driving the stepping motor 51, the 1st cylindrical body 21 and the 2nd cylindrical body 31 are eccentrically rotated, and the distance between 21 A of opposing surfaces and 31A is changed periodically. At this time, the light detectors 3a and 3b detect the transmitted light transmitted through the measurement sample W interposed between the opposing surfaces 21A and 31A. Here, it is assumed that the phase θ _S that is a sampling point at which the signal receiving unit 64 receives the light intensity signal from the photodetectors 3a and 3b is predetermined by the operator before the measurement.

At the phase θ _S that is the sampling point, the signal receiving unit 64 receives the light intensity signal and outputs it to the comparative analysis unit 66. The comparative analysis unit that has received the light intensity signal from the signal reception unit 64 uses the light intensity signal at the phase θ _S that is two sampling points and the distance L between the facing surfaces 21A and 31A calculated by the distance calculation unit 65. Absorbance and visible light absorbance are calculated. Further, the COD (chemical oxygen demand) of the measurement sample W is calculated from these absorbances.

According to the photometric analyzer 1 of the present embodiment configured as described above, when the distance θ between the phase θ ₅₁ and the opposing surfaces 21A and 31A is maximized when the distance L between the opposing surfaces 21A and 31A is minimized. Since the phase θ _S for sampling the light intensity signal can be set so as to be changeable with respect to the phase θ ₅₁ , the measurement range can be widened at low cost without any physical change, and the low-concentration measurement sample W To a high-concentration measurement sample W.

  In addition, since a stepping motor is used as the motor 51 of the drive unit 5, since the angle error is small, high measurement accuracy can be ensured.

  Second Embodiment

  Next, a second embodiment of the photometric analyzer of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the thing corresponding to the said 1st Embodiment.

  The photometric analyzer 1 according to this embodiment differs from the first embodiment in the functional configuration of the information processing apparatus 6. That is, the information processing apparatus 6 according to the present embodiment includes a motor control unit 61, a phase detection unit 62, a phase setting unit 63, a signal reception unit 64, a coefficient calculation unit 67, a comparison analysis unit 66, and the like as illustrated in FIG. Function as.

The phase setting unit 63 is configured so that the phase θ ₂₁ , θ ₃₁ and the opposing surfaces 21A, 31A when the distance L between the opposing surfaces 21A, 31A between the first cylindrical body 21 and the second cylindrical body 31 is the minimum. The phase θ _S that is a plurality of sampling points for sampling the light intensity signal from the photodetector is set to be changeable between the phases θ ₂₁ and θ ₃₁ when the distance L is maximum, and the setting signal is The signal is output to the signal receiving unit 64 and is also output to the coefficient calculating unit 67.

The coefficient calculation unit 67 receives a result of measuring a measurement sample (for example, a calibration solution) W having a known concentration in the phase θ _S set in advance by the phase setting unit 63, and determines between the facing surfaces 21A and 31A from the measurement result. The distance L between the opposing surfaces 21A and 31A calculated at the phase θ _{S as} two sampling points is further used to calculate the coefficient K (= 10 / (L (1) -L (2))) is calculated.

  The comparative analysis unit 66 receives the light intensity signal received by the signal receiving unit 64 from the photodetectors 3a and 3b, and further, based on the coefficient K calculated by the coefficient calculating unit 67, (Equation 1) of the first embodiment. ) To calculate the ultraviolet absorbance, visible light absorbance and COD of the measurement sample W.

  Next, the operation of the photometric analyzer 1 of this embodiment will be described.

First, a measurement sample (for example, calibration solution) W having a known concentration is stored in the analysis tank 4, and the first cylindrical body 21 and the second cylindrical body are immersed in the measurement sample W. As in the first embodiment, the absorbance is measured at the phase θ _S set in advance by the phase setting unit 63. Based on the measurement result, the coefficient calculator 67 calculates the coefficient K.

  Thereafter, the calibration liquid W is removed from the analysis tank 4, the measurement sample W having an unknown concentration is accommodated, and the first cylindrical body 21 and the second cylindrical body are immersed in the measurement sample W.

In the same manner as in the first embodiment, the signal receiving unit 64 receives the light intensity signal at the phase θ _S that is the sampling point, and outputs it to the comparative analysis unit 66. The comparative analysis unit 66 calculates the ultraviolet absorbance and the visible light absorbance using the light intensity signals at the two sampling phases θ _S and the coefficient K calculated by the coefficient calculation unit 67. Further, the COD (chemical oxygen demand) of the measurement sample W is calculated from these absorbances.

  According to the present embodiment configured as described above, as in the first embodiment, the measurement range can be widened at low cost without any physical change, and the low concentration measurement sample W can be expanded to a high concentration. It is possible to measure up to the measurement sample W.

  The present invention is not limited to the above embodiment.

  For example, in the embodiment, a stepping motor is used as the motor of the driving unit. However, a motor other than the stepping motor, for example, an AC motor may be used. In this case, the rotational phase of the AC motor is detected using an encoder.

  Also, other motors can be used as long as the relationship with the phase is known.

  Further, although the phase is detected using the pulse train signal to the stepping motor, the phase of each cylindrical body may be detected individually.

  Furthermore, in the said embodiment, although the distance between opposing surfaces is periodically changed by rotating eccentrically the 1st cylindrical body and the 2nd cylindrical body, one cylindrical body is eccentrically rotated. The other cylindrical body may be fixed and the distance between the opposing surfaces may be changed periodically.

  In addition, the cylindrical body of the embodiment has a cylindrical shape, but may have an elliptical cylindrical shape or the like.

  In addition, in the above-described embodiment, two photodetectors for ultraviolet detection and visible light detection are used, but ultraviolet light and visible light may be detected using one photodetector. In this case, ultraviolet rays and visible rays are detected by alternately switching between the ultraviolet ray detecting interference filter and the visible ray detecting interference filter.

  In addition, a part or all of the above-described embodiments and modified embodiments may be combined as appropriate, and the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit thereof. Needless to say.

1 is a schematic configuration diagram of a photometric analyzer according to a first embodiment of the present invention. The figure which shows the change of the eccentric rotation of the cylindrical body in the same embodiment, the light intensity signal at that time, and the distance between opposing surfaces. The equipment block diagram of the information processing apparatus in the embodiment. The function block diagram of the information processing apparatus in the embodiment. The figure which shows the setting range of the phase which is a sampling point in the embodiment. The function block diagram of the information processing apparatus of the photometry analyzer which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photometric analyzer 2 ... Light source 3 ... Photodetector 21, 31 ... Cylindrical body (1st cylindrical body, 2nd cylindrical body)
W ... Samples 21A, 31A ... Opposing surface L ... Distance between opposing surfaces 62 ... Phase detector θ ... Phase θ _S ... Sampling point phase 63 ... Phase Setting unit 64... Signal receiving unit 66... Comparative analysis unit 51.

Claims (4)

A cylindrical body having a light source therein and a cylindrical body having a photodetector for detecting light from the light source are disposed in the measurement sample so as to be spaced apart, and at least one of the cylindrical bodies is rotated. A photometric analyzer that periodically expands and contracts the distance between opposing surfaces of the two cylindrical bodies and analyzes a measurement sample interposed between the opposing surfaces,
A phase detector for detecting the phase of rotation of the cylindrical body;
Multiple phases for sampling the light intensity signal from the photodetector can be changed between the phase when the distance between the opposing surfaces is minimum and the phase when the distance between the opposing surfaces is maximum. A phase setting unit to be set to
Based on the phase detection signal from the phase detection unit, a signal reception unit that receives light intensity signals in a plurality of phases set by the phase setting unit;
A photometric analyzer comprising: a comparison analysis unit that analyzes the measurement object by comparing light intensity signals at each phase received by the signal reception unit. When the signal reception unit has the same rotation phase of the cylindrical body indicated by the phase detection signal from the phase detection unit and each phase set by the phase setting unit, the light intensity signal of the rotation phase The photometric analyzer according to claim 1, wherein The cylindrical body is rotated by a stepping motor,
The photometric analyzer according to claim 1 or 2 , wherein the phase detection unit detects a phase of rotation of the cylindrical body using a pulse train signal to the stepping motor. The phase detector, using a signal from the encoder, the photometric analyzer according to claim 1 or 2 wherein detecting the rotation phase of the tubular body.

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