JP2016136122A - Device for measuring concentration of dissolved substance in liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure concentration of a dissolved ultraviolet absorbing material having ultraviolet light absorption characteristics in liquid.SOLUTION: A device for measuring concentration of dissolved substance in liquid (1A) includes: a light source (2); a quartz tube (4) for allowing liquid containing a dissolved substance of a measuring object to pass through; an optical member (5) which converts ultraviolet light emitted from the light source (2) and passing through the quartz tube (4) into light having a wavelength of a visible light band or higher; and a light receiving element (3) which detects the light passing through the optical member (5).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dissolved substance concentration measuring apparatus in a liquid.

  The dissolved matter in liquid that absorbs ultraviolet rays has many industrial and commercial applications. A typical example of such a dissolved substance in liquid is ozone. As a method for measuring the concentration of ozone in a liquid, various measuring methods such as a diaphragm polarographic method, a method of measuring an electrolytic potential difference or an oxidation-reduction potential have been proposed in addition to a concentration detection method using deep ultraviolet rays. In a commercially available method for measuring the dissolved ozone concentration in ozone water, an ultraviolet absorption method is mainly used.

  Patent Document 1 discloses a basic ozone concentration detection method. In the ozone concentration detection method described in Patent Document 1, the amount of ultraviolet light reaching the light receiving element when raw water in which ozone is not dissolved passes through the measurement cell and the ozone water in which ozone is dissolved pass through the measurement cell. The difference between the amount of ultraviolet light reaching the light receiving element during the measurement is measured, and the amount of ultraviolet light absorbed by ozone in the ozone water is calculated. And in the ozone concentration detection method of patent document 1, the light absorbency measuring method which converts ozone concentration from the light absorbency of this ultraviolet-ray is employ | adopted.

  Furthermore, Patent Document 1 discloses a technique for improving the ozone concentration measurement technique based on the absorbance measurement method. In this improved technique, an optical condensing filter is interposed in the measurement optical system, and light passing through the optical condensing filter is used as detection light for ozone concentration measurement. The optical condensing filter includes a wavelength selection function for extracting a specific single wavelength ultraviolet light with respect to a continuous wavelength ultraviolet light emitted from the light emitting element, and a condensing function for condensing the single wavelength ultraviolet light. Are both optical components.

  Patent Document 2 discloses a theory for measuring the dissolved concentration of ozone by the absorbance of ultraviolet rays when passing through a measurement cell, and a technique based on the theory.

  In the technique of Patent Document 2, an ultraviolet lamp or the like is used as a light source that emits detection light for measuring ozone concentration. Two optical paths are provided in the measurement cell through which the ultraviolet light that is the detection light passes. These two optical paths differ from each other in the cross-sectional area of the portion through which the liquid or gas passes. The ozone concentration is measured using a difference detection method between the change in the amount of received light detected for one optical path and the change in the amount of received light detected for the other optical path. In the apparatus described in Patent Literature 2, the detection unit that detects the passing light passing through the measurement cell is arranged outside the measurement cell. An aperture and a reflector are arranged so that the light from the ultraviolet lamp passes through a desired location in the measurement cell and is received by the detection unit. With such an apparatus configuration, it is possible to clearly discriminate the difference in the amount of received light with respect to light of two optical paths having different optical path lengths.

Patent No. 5239000 (issued July 17, 2013) JP-A-6-003266 (published on January 11, 1994)

  In the technique disclosed in Patent Document 1, a conventional light receiving element is used. That is, in the apparatus disclosed in Patent Document 1, the light receiving elements having light receiving sensitivity with respect to the emitted light of the light source are uniformly arranged. However, when the wavelength of the light emitted from the light source is in the deep ultraviolet region, in the most commonly available Si-based, GaP-based, or GaAs-based light receiving element, the wavelength of the received light becomes shorter. The light receiving sensitivity will be extremely low. For this reason, when the ozone dissolved concentration is measured for a solution in a state where the ozone dissolved concentration is low, the detection light becomes less dimmed and the detection error becomes larger. As a result, when the apparatus disclosed in Patent Document 1 is incorporated in an ozone water generator and used, there is a problem that the ozone dissolved concentration is managed with a large concentration detection error.

  In the technique disclosed in Patent Document 2, a light source is selected and used regardless of the directivity of the light source. For this reason, when setting two optical paths for measuring the amount of light reduction, the range of light emitted from the light source is limited using an aperture. However, when the wavelength of the light emitted from the light source is in the deep ultraviolet region, as described above, the light receiving sensitivity of a general light receiving element is low. For the light receiving element having low sensitivity, a structure for losing the emitted light amount (used light amount) of the light source is intentionally adopted. Therefore, it is necessary to employ a light source having an unnecessarily large energy in order to secure a received light amount that matches the detection accuracy.

  In addition, regarding the restriction of the emission light range of the light source by the aperture, the technique disclosed in Patent Document 2 is configured to restrict the opening in different radiation directions due to the nature of the light source. For this reason, when a variation in irradiation intensity occurs when the partial deterioration of the light source itself begins, it becomes easier for the light receiving element to be affected by the variation in irradiation intensity. As a result, the detection error increases.

  Therefore, a solution concentration measuring apparatus in liquid that can measure the concentration of a solution having a low concentration of dissolved substances is required.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an apparatus for measuring the concentration of dissolved matter in liquid that can accurately measure the dissolved concentration in liquid of an ultraviolet light-absorbing material having ultraviolet light absorption characteristics. There is to do.

  In order to solve the above-described problem, an apparatus for measuring a concentration of dissolved matter in liquid according to one embodiment of the present invention passes through a liquid including a light source that emits ultraviolet light and a dissolved object to be measured having ultraviolet light absorption characteristics. An optical member that converts the ultraviolet light that is emitted from the light source and passes through the conduit portion into light having a wavelength equal to or greater than the visible light band, and a light receiving element that detects the light that has passed through the optical member. It is characterized by having.

  According to one aspect of the present invention, there is an effect that the dissolved concentration in a liquid of an ultraviolet light absorbing material having ultraviolet light absorption characteristics can be accurately measured.

(A) And (b) is sectional drawing which shows schematic structure of the submerged dissolved substance concentration measuring apparatus which concerns on Embodiment 1 of this invention. It is a graph which shows the result of having measured the attenuation | decrease rate of the deep ultraviolet light with respect to the ozone water of a known ozone concentration with the apparatus structure shown to (a) and (b) of FIG. It is sectional drawing which showed typically the light which reaches | attains from a light source to a light receiving element, when the cross-sectional shape of a quartz tube is circular. (A) And (b) is sectional drawing which shows schematic structure of the dissolved substance density | concentration measuring apparatus in liquid which concerns on Embodiment 2 of this invention, (c) is dissolved in liquid which concerns on Embodiment 2 of this invention. It is a figure which shows an example of the signal circuit mounted in a physical concentration measuring apparatus. (A) And (b) is sectional drawing which shows schematic structure of the submerged dissolved substance concentration measuring apparatus which concerns on Embodiment 3 of this invention. (A) And (b) is sectional drawing which shows schematic structure of the submerged dissolved substance concentration measuring apparatus which concerns on Embodiment 4 of this invention.

Embodiment 1
Hereinafter, an embodiment of the present invention will be described in detail. FIGS. 1A and 1B are cross-sectional views showing a schematic configuration of the in-liquid dissolved matter concentration measuring apparatus 1A according to the present embodiment.

  As shown in FIGS. 1A and 1B, a dissolved substance concentration measuring apparatus 1A in the liquid according to the present embodiment includes a light source 2 that emits ultraviolet light, a light receiving element 3, a quartz tube 4, and an optical device. A member 5, a light receiving element 6, a reflecting element 7, O-rings 8 a and 8 b, a light shielding member 9, and a housing 10 are provided.

  Here, an imaginary axis passing through the center of the light source 2 and the center of the light receiving element 3 is defined as the y axis, the central axis of the quartz tube 4 is defined as the x axis, and an axis perpendicular to both the x axis and the y axis is defined as the z axis. 1A shows a cross section of the dissolved substance concentration measuring apparatus 1A in the xy plane passing through the light source 2 and the light receiving element 3, and FIG. 1B shows the light source 2, the light receiving element 6 and the reflecting element. 7 shows a cross-section of the dissolved substance concentration measuring apparatus 1A in the liquid on the yz plane passing through 7;

  The light source 2 and the light receiving element 3 are arranged so as to face each other with the quartz tube 4 interposed therebetween. The optical member 5 is disposed between the quartz tube 4 and the light receiving element 3. The light emitted from the light source 2 passes through the quartz tube 4 and the optical member 5 and reaches the light receiving element 3 (optical path A shown in FIG. 1A). The optical member 5 is a wavelength conversion member that receives the emitted light (ultraviolet light) of the light source 2 that has passed through the quartz tube 4, converts the light into light having a wavelength longer than the visible light band, and emits the light to the light receiving element 3. The light receiving element 3 detects the light whose wavelength has been converted by the optical member 5. The quartz tube 4 is a tube that also serves as a path through which the liquid S in which the concentration measurement object is dissolved passes.

  In the dissolved substance concentration measurement apparatus 1A in the liquid, the emission range of the emitted light is not limited with respect to the light source 2, and the light receiving element 3 is arranged so as to match the emission characteristics of the emitted light that the light source 2 has. Specifically, the arrangement is such that light in the vicinity of the intensity peak of the radiation pattern of the light source 2 reaches the light receiving element 3. Furthermore, the reason why the quartz tube 4 is used as a tube that also serves as a path for passing the liquid S in which the concentration measurement object is dissolved is that the quartz tube 4 does not absorb ultraviolet light and has an influence on the dissolved concentration measurement accuracy. Because there is almost no.

  In the dissolved substance concentration measuring apparatus 1A in the liquid, as shown in FIG. 1B, the light receiving element 6 and the reflecting element 7 are arranged on the light source 2 side in the quartz tube 4. The light receiving element 6 is disposed in the vicinity of the light source 2 and is provided for monitoring the light amount when the light source 2 emits light. The reflection element 7 is provided to guide the light emitted from the light source 2 to the light receiving element 6. The reflection element 7 has a wavelength conversion function of converting the emitted light (ultraviolet light) of the light source 2 into light having a wavelength longer than the visible light band and reflecting the light to the light receiving element 6. In the dissolved substance concentration measuring apparatus 1A in the liquid, the light receiving element 6 is set at a position as shown in FIG. 1B, and the reflecting element 7 is arranged. Part of the ultraviolet light emitted from the light source 2 first enters the reflective element 7. Then, the light is converted into light having a visible light band or higher by the reflection element 7, then reflected by the surface of the reflection element 7 opposite to the light source 2 and received by the light receiving element 6. In this way, by converting a part of the ultraviolet light emitted from the light source 2 into light of the visible light band or higher and receiving the light by the light receiving element 6, the light quantity at the time of light emission of the light source 2 can be monitored. And by monitoring the light quantity at the time of the light emission of the light source 2, the influence of the fall of the emitted light quantity of the light source 2 at the time of a measurement can be prevented. In the configuration shown in FIG. 1B, the cross-sectional shape of the quartz tube 4 is annular. However, the cross-sectional shape of the quartz tube 4 is not limited to an annular shape, and may be a rectangular shape.

  The housing 10 is for holding the light source 2, the light receiving element 3, and the optical member 5, and has openings 11a and 11b. The light source 2, the light receiving element 3, and the optical member 5 are disposed in the openings 11a and 11b. As a result, the light source 2 and the optical member 5 are arranged to face each other with the quartz tube 4 interposed therebetween. Further, the liquid S containing the dissolved matter flows through the quartz tube 4, so that the refractive index difference between the quartz tube 4 and the liquid S becomes small. For this reason, the light loss from the light source 2 to the optical member 5 is caused mainly by the reflection on the surface of the quartz tube 4.

  Further, in the dissolved substance concentration measuring apparatus 1A in the liquid, preventing unnecessary light from reaching the light receiving element 3 is effective in improving the detection accuracy of the dissolved concentration. In order to prevent such unnecessary light from reaching the light receiving element 3, as shown in FIGS. 1A and 1B, a light shielding member 9 is provided. The light shielding member 9 may be provided independently of the housing 10 or may be integrated with the housing 10. Further, the light shielding member 9 is not for limiting the opening of the light emitted from the light source 2.

  The wavelength of the light source 2 can be appropriately changed according to the absorption wavelength of the dissolved substance to be measured. When measuring the dissolved ozone concentration of ozone water, since the absorption peak of dissolved ozone is in the range of wavelength 260 nm to 270 nm, a deep ultraviolet LED light source having a wavelength of 270 nm is adopted as the light source 2.

  Further, as the light receiving element 3, for example, a Si photodiode can be cited. The sensitivity peak of the Si photodiode is the most general sensitivity peak wavelength region, and is in the range of 700 nm to 1000 nm. Further, a photo IC diode can be used as the light receiving element 3. The photo IC diode is adjusted by an optical filter or the like so that the light receiving sensitivity peak is around 540 nm in accordance with the visibility band. In general, the photo IC diode has an amplifier circuit in the inside thereof, and compensates for a decrease in the amount of light for sensitivity adjustment by an optical filter or the like.

  The photodiode described above has low light receiving sensitivity in the ultraviolet wavelength region (wavelength of 400 nm or less). Even in the case of a Si photodiode having a light receiving sensitivity band with respect to the wavelength 270 nm of the emitted light of the deep ultraviolet LED light source, the light receiving sensitivity is 0.1 A which is not more than one third of the peak value 0.36 A / W. Reduced to about / W.

  In the dissolved substance concentration measuring apparatus 1A in the liquid, the optical member 5 has an excitation wavelength region in the wavelength region of deep ultraviolet light (wavelength 200 nm to 400 nm), and emits light in the vicinity of a wavelength of 540 nm by the excitation.

  By using such an optical member 5, the light receiving sensitivity of the photodiode as the light receiving element 3 is improved to 0.3 A / W, which is 3 as compared with a Si photodiode having a light receiving sensitivity band with respect to a wavelength of 270 nm. Doubled. With respect to the light receiving element 3, it is possible to realize light receiving sensitivity equivalent to that when the light amount of the light source 2 is increased, and it is not necessary to employ a light source with unnecessarily large energy. Therefore, even when the ozone dissolved concentration is measured for a solution having a low ozone dissolved concentration, it is easy to secure the amount of light received by the light receiving element 3 necessary for the concentration measurement.

  The following two types of glass members can be used as the optical member 5 that converts the wavelength by making the deep ultraviolet light incident as described above. In the in-liquid dissolved matter concentration measuring apparatus 1A, a flat glass member with a 5 mm square incident surface size for deep ultraviolet light is used as the optical member 5.

 (i) A plate-like glass member containing a light emitter having an excitation wavelength in the deep ultraviolet wavelength region and an emission wavelength in the visible light wavelength region.

 (ii) A flat glass member in which a phosphor having an excitation wavelength in the deep ultraviolet wavelength region and an emission wavelength in the visible light wavelength region is coated and fixed on the surface. However, the surface on which the phosphor is applied is set on the incident surface side of the deep ultraviolet light emitted from the light source 2.

  The merit that the material of the optical member 5 is glass is that the glass has a transmission wavelength band in the wavelength range of visible light where the deep ultraviolet light is excited, and is not deteriorated by the deep ultraviolet light. Further, when the glass member of the above type (ii) is used as the optical member 5, SOG (Spin on Glass) or low-melting glass can be used as a phosphor fixing agent to the glass member. By using such a fixing agent, a method such as firing by high-temperature heating (200 ° C. or higher) can be adopted as a method for fixing the phosphor, and the stability of the performance of the optical member 5 after fixing the phosphor can be improved. Can be increased. That is, the measurement accuracy of the dissolved substance concentration can be stabilized for a long time.

  Moreover, the translucent board | substrate with which the reflective film surface comprised with Al was formed can be used for the reflective element 7 mentioned above. In this case, the light source 2 is applied to the surface of the translucent substrate opposite to the reflective film surface by applying a phosphor having an excitation wavelength in the deep ultraviolet wavelength region and an emission wavelength in the visible light wavelength region. A part of the ultraviolet light emitted from the light can be converted into light in the visible light band and reflected. In addition, as a material of a translucent substrate, quartz material is mentioned, for example. Examples of the phosphor include SiAlON-based phosphors.

  In addition, the measurement optical system of the in-liquid dissolved matter concentration measuring apparatus 1A can cope with both the case where there is a flow and the case where there is no flow with respect to the liquid S containing the dissolved matter (such as ozone) to be measured. is there. When there is no flow in the liquid S, the dissolved substance concentration can be measured by making one of the two openings of the quartz tube 4 closed and putting the liquid S therein.

  When there is a flow in the liquid S, the in-liquid dissolved matter concentration measuring apparatus 1A is connected to an external pipe for flowing the liquid S. As shown in FIG. 1A, the dissolved substance concentration measuring apparatus 1A is connected to an external pipe by connecting the casing 10 between the pipe connecting part 12a and the pipe connecting part 12b. ing. When the casing 10 is connected to an external pipe via the pipe connecting portion 12a and the pipe connecting portion 12b, the concentration measurement target liquid S continues to flow into the quartz tube 4 held in the casing 10. Therefore, the concentration of dissolved matter in the liquid S can be continuously measured.

  The liquid S that is a measurement target of the dissolved substance concentration measuring apparatus 1A in the liquid is not particularly limited as long as it is a liquid containing an ultraviolet light absorbing material. For example, in addition to the ozone water described above, the liquid S is hypochlorous acid water. May be. That is, the dissolved substance concentration measuring apparatus 1A in liquid can accurately measure the dissolved concentration in liquid such as water not only for ozone but also for other ultraviolet light absorbing materials such as hypochlorous acid.

  In addition, in order to connect the quartz tube 4 and the flow paths 13a and 13b of the pipe connection portions 12a and 12b, the connection portions between the pipe connection portions 12a and 12b and the housing 10 are provided with O-rings 8a and 8b for preventing water leakage. Is provided.

  Finally, FIG. 2 shows the result of measuring the extinction rate of deep ultraviolet light with respect to ozone water having a known ozone concentration by the apparatus configuration shown in FIGS. FIG. 2 is a graph showing the relationship between the known ozone concentration and the attenuation rate (darkening rate) of the amount of light received by the light receiving element 3. In the apparatus configuration at the time of measurement, a deep ultraviolet LED light source having a wavelength of 270 nm is used as the light source 2, and a photo IC diode having a sensitivity peak in the vicinity of a wavelength of 540 nm is used as the light receiving element 3.

As shown in FIG. 2, the log value of the light extinction rate (a value obtained by multiplying the log ₁₀ value of the light extinction rate by −1) and the dissolved ozone concentration (unit: mg / kg) with respect to ozone water having a known concentration passed through the quartz tube 4. L) is proportional. From this, in the dissolved substance concentration measuring apparatus 1A in the liquid, the attenuation phenomenon due to the absorption of ultraviolet light of dissolved ozone is caused by converting the ultraviolet light emitted from the light source 2 into excitation light above the visible light band by the optical member 5. It can be seen that even if the amount of received light is indirectly measured by the light receiving element 3, it can be detected. As a result, it can be seen that the configuration of the dissolved substance concentration measuring apparatus 1A in the liquid has no problem as an optical system for measuring the ozone concentration in the liquid. That is, from FIG. 2, the measurement performance of the ozone concentration is not affected by the variation in the excitation reaction at the time of wavelength conversion in the optical member 5, and the device configuration shown in (a) and (b) of FIG. It can be seen that the reduced amount of deep ultraviolet light can be measured as the reduced amount of light in the visible light band. Note that the experimental results shown in FIG. 2 are measured by extracting a signal that becomes an input value to the concentration conversion arithmetic circuit.

<Effect of the shape of the quartz tube 4>
The cross-sectional shape of the quartz tube 4 is not greatly restricted by the structural factors of the dissolved substance concentration measuring apparatus 1A in the liquid, and may be an annular shape or a rectangular shape. However, the cross-sectional shape of the quartz tube 4 is preferably an annular shape. Hereinafter, this reason will be described with reference to FIG. FIG. 3 is a cross-sectional view schematically showing light reaching the light receiving element 3 from the light source 2 when the quartz tube 4 has an annular cross-sectional shape.

  As shown in FIG. 3A, when the liquid S does not flow through the quartz tube 4, among the light emitted from the light source 2, the distance from the light source 2 to the light receiving surface of the light receiving element 3 and the light receiving element 3 The light component within the irradiation range determined by the light receiving range only reaches the light receiving element 3. For example, when the light receiving region of the light receiving element 3 has a quadrangular shape, the irradiation range is a range of a quadrangular pyramid with the arrow in FIG. That is, the irradiation range is within a cone range having the center of the light source 2 as the apex and the light receiving region of the light receiving element 3 as the bottom surface.

  On the other hand, as shown in FIG. 3B, when the liquid S flows into the quartz tube 4 and the quartz tube 4 is filled with the liquid S, the light emitted from the light source 2 and the quartz tube 4 and Due to the refracted light effect with the liquid S, the ratio of the light component reaching the light receiving element 3 out of the light emitted from the light source 2 is increased, and the radiation range of the light reaching the light receiving element 3 in the light source 2 is widened. Become. Therefore, it is possible to increase the amount of light reaching the light receiving element 3 from the light source 2 while maintaining the fluctuation of the optical path length in a small range. As a result, it is possible to detect by increasing the difference in received light amount (reduced light amount) at the light receiving element 3 due to the absorption of the dissolved matter that is important in the dissolved matter concentration measurement. Note that the amount of light reduction refers to the amount of light reaching the light receiving element 3 from the light source 2 when passing through the liquid S having no measurement target dissolved matter, and the light source when passing through the liquid S with the measurement target dissolved matter. 2 represents the difference from the amount of light reaching the light receiving element 3 from 2. For example, if the liquid S is ozone water, the amount of light reaching the light receiving element 3 from the light source 2 when passing through water without ozone, and the light receiving element 3 reaching from the light source 2 when passing through ozone water. The difference from the amount of light is the amount of light reduction.

  Furthermore, when the refractive index difference between the quartz tube 4 and the liquid S is smaller than 0.1, the reflection of light at the boundary between the liquid S and the quartz tube 4 is greatly reduced. Therefore, the effect of increasing the amount of light reaching the light receiving element 3 from the light source 2 is further improved.

  As described above, the measurement accuracy of the dissolved concentration of the dissolved matter in the liquid S can be improved by the cross-sectional shape of the quartz tube 4 being annular. The experimental results shown in FIG. 2 are the results of experiments using a quartz tube 4 having an annular cross-sectional shape. From the experimental results of FIG. 2, it can be proved that the influence on the measurement of the difference in the amount of received light necessary for the concentration measurement is small as described above.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals and description thereof is omitted. FIG. 4 is a cross-sectional view showing a schematic configuration of the in-liquid dissolved matter concentration measuring apparatus 1B according to the present embodiment.

  The in-liquid dissolved matter concentration measuring apparatus 1B according to the present embodiment is different from the first embodiment in that the light source 22 includes a plurality of light emitting sources. As shown in FIG. 4, the light source 22 includes a plurality of light emitting sources 22a, 22b, and 22c. The light emitting sources 22a, 22b, and 22c are arranged in a predetermined range from the center of the light source 22 when viewed from the light receiving element 3 side. The light source 22 functions as a light source having a plurality of light emitting sources.

  As shown in FIG. 4, the light emitting sources 22a, 22b, and 22c are arranged in a circle having a radius R from the light emitting center of the light source 22 viewed from the light receiving element 3 side. The light sources 22a, 22b, and 22c have a radius R between each other. The radius R is defined as the distance L between the shortest distance between the center of the light emission range of the light source 22 and the light receiving element 3, the normal line of the light receiving surface of the light receiving element 3 passing through the center of the light emission range of the light source 22, and the normal line and the light source. When the angle formed by the line connecting the edges of the light emission range 22 is θ, it is expressed by the following formula (1).

R = Ltanθ (θ ≦ 10 °) Equation 1
In the in-liquid dissolved matter concentration measuring apparatus 1B, for example, the distance L is set to 20 mm, and the radius R is set to 3.5 mm.

  According to the configuration of the in-liquid dissolved matter concentration measuring apparatus 1B, the optical path lengths from the light emitting sources 22a, 22b, and 22c to the light receiving element 3 are different from each other by about 2%. Such a difference in optical path length can be considered to be small as an influential factor when detecting a change in the amount of light due to absorption of ultraviolet light by a dissolved material. Therefore, if the light emission range is within the circle having the radius R shown by the above formula (1), the change in the amount of light received by the light receiving element 3 is converted into the density, resulting in a difference in optical path length. The error can be reduced. In addition, it can be considered that a plurality of light sources such as the light sources 22 a, 22 b, and 22 c function as one light source 22.

  Further, the light source 22 may be a surface light source whose entire light emission range is a circular area having a radius R. Further, in the in-liquid dissolved matter concentration measuring apparatus 1B, the number of light emitting sources present in a circle having a radius R does not become a restriction on the performance of the apparatus.

[Embodiment 3]
The following will describe still another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals and description thereof is omitted. (A) and (b) of FIG. 5 is sectional drawing which shows schematic structure of 1 C of dissolved substance concentration measuring apparatuses in liquid which concern on this embodiment.

  As shown in FIGS. 5A and 5B, the dissolved matter concentration measuring apparatus 1C according to this embodiment includes a light source 32 that emits ultraviolet light, light receiving elements 33a and 33b, a quartz tube 34, and the like. , Optical members 35a and 35b, a light receiving element 36, a reflecting element 37, O-rings 8a and 8b, a light shielding member 39, and a housing 40. The quartz tube 34 is longer in length than the quartz tube 4 of the dissolved substance concentration measurement apparatus 1A according to the first embodiment. The light source 32 is, for example, a deep ultraviolet LED light source having a wavelength of 270 nm. The optical members 35a and 35b are made of, for example, a glass member coated with the above-described phosphor. The light receiving elements 33a and 33b are, for example, the above-described photo IC diodes.

  Here, (a) of FIG. 5 shows a cross section of the dissolved substance concentration measuring apparatus 1C in the xy plane passing through the light source 32 and the light receiving elements 33a and 33b, and (b) of FIG. The cross section of 1 C of dissolved substance concentration measuring apparatuses in the liquid in the yz plane which passes the element 36 and the reflective element 37 is shown.

  As shown in FIGS. 5A and 5B, the in-liquid dissolved matter concentration measuring apparatus 1C according to the present embodiment particularly includes two light receiving elements 33a and 33b and two optical members 35a and 35b. It differs from the said Embodiment 1 and 2 by the point provided. Hereinafter, the configuration of the in-liquid dissolved matter concentration measuring apparatus 1C according to the present embodiment will be described.

  The light receiving elements 33 a and 33 b are arranged based on the radiation characteristics of the light source 32 without limiting the opening of the light emission range of the light source 32. More specifically, the light receiving elements 33a and 33b are arranged so that the amount of light reaching both the light receiving elements 33a and 33b is maximized after setting the directivity of the light source 32 to about 45 ° on one side of the radiation pattern. ing.

  In the in-liquid dissolved matter concentration measuring apparatus 1C, two optical paths A and B are formed between the light source 32 and the light receiving elements 33a and 33b, respectively. That is, the amount of light reduction detected by the light receiving elements 33a and 33b is a result of the light emitted from the light source 32 being absorbed by the dissolved matter when passing through two different locations in the liquid S in the quartz tube 34. Is based. Therefore, the light reduction amounts detected by the light receiving elements 33a and 33b have different values depending on the optical path length difference between the optical path A and the optical path B.

Here, when light absorption by the liquid S such as ozone water or hypochlorous acid water occurs, the light is dissolved from the ratio signal of the light reduction caused by the optical path difference between the two optical paths A and B from the light source 32 to the light receiving elements 33a and 33b. It is known that a conversion operation for measuring the concentration is possible. Specifically, when the amounts of light received by the light receiving elements 33a and 33b are I1 and I2, respectively, the dissolved substance concentration C to be measured is expressed by the following formula 2.
C ∝ log ₁₀ (I1 / I2) Equation 2
Conversion calculation can be performed based on the above.

  This conversion calculation is the amount of light that the light emitted from the light source 32 reaches the light receiving elements 33a and 33b in a state where there is no dissolved matter in the liquid S (the reference in the liquid dissolved matter concentration measuring apparatus 1A according to the first embodiment). This means that the ratio of the amount of light absorbed by the dissolved substance (the ratio caused by the optical path difference between the optical paths A and B) does not change even if the amount of light) is changed. Therefore, the conversion calculation for measuring the dissolved concentration can be performed stably.

  As a result, according to the configuration of the in-liquid dissolved matter concentration measuring apparatus 1C, for example, the concentration measurement accuracy of dissolved matters such as ozone and hypochlorous acid dissolved in water is improved.

Further, as shown in FIG. 4C, the solution concentration measuring apparatus 1C in the liquid is equipped with a measuring circuit 33c that performs circuit processing using the ratio of the received light amounts I1 and I2 of the light receiving elements 33a and 33b as a light reception signal. ing. The measurement circuit 33c is, for example, a log amplifier IC that receives signals I1 and I2 and obtains log ₁₀ (I1 / I2) as an output signal. By using such a measurement circuit 33c, the signal processing accuracy of the circuit for concentration measurement is also improved. As a result, the reliability of the measured value of the dissolved substance concentration is also increased.

  Further, in the in-liquid dissolved matter concentration measuring apparatus 1 </ b> C, as shown in FIG. 5A, the light receiving element 36 and the reflecting element 37 are arranged on the light source 32 side in the quartz tube 34. The light receiving element 36 is disposed in the vicinity of the light source 32 and is provided for monitoring the amount of light when the light source 32 emits light. The reflection element 37 is provided to guide the light emitted from the light source 32 to the light receiving element 36. The positional relationship between the light receiving element 36 and the reflecting element 37 is different from the positional relationship between the light receiving element 6 and the reflecting element 7 shown in FIG. The reflection element 37 has a wavelength conversion function of converting the light emitted from the light source 2 (ultraviolet light) into light having a wavelength longer than the visible light band and reflecting the light to the light receiving element 36. The reflection element 37 guides the light emitted from the light source 32 to the light receiving element 36, whereby a part of the ultraviolet light emitted from the light source 32 is converted into light having a visible band or higher and is received by the light receiving element 36. Therefore, according to the configuration of the dissolved substance concentration measurement apparatus 1C in the liquid, the light amount at the time of light emission of the light source 32 can be monitored.

  The housing 40 is for holding the light source 32, the light receiving elements 33a and 33b, and the optical members 35a and 35b, and has openings 41a, 41b, and 41c. The light source 32, the light receiving elements 33a and 33b, and the optical members 35a and 35b are disposed in the openings 41a, 41b, and 41c. As a result, the light source 32 and the optical members 35a and 35b are arranged to face each other with the quartz tube 34 interposed therebetween. Thereby, the light quantity loss of the emitted light of the light source 32 can be reduced.

  Further, in the dissolved substance concentration measuring apparatus 1C in the liquid, it is effective to prevent the unnecessary light from reaching the light receiving elements 33a and 33b in order to improve the detection accuracy of the dissolved concentration. In order to prevent such unnecessary light from reaching the light receiving elements 33a and 33b, as shown in FIGS. 5A and 5B, a light shielding member 39 is provided. The light shielding member 39 may be provided independently of the housing 40 or may be integrated with the housing 40. The light shielding member 39 is not for limiting the opening of the light emitted from the light source 32, but for shielding unnecessary light. The material of the light blocking member 39 may be any material that can absorb light in the visible light band or higher wavelength-converted by the optical members 35a and 35b.

[Embodiment 4]
The following will describe still another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals and description thereof is omitted. 6A and 6B are cross-sectional views showing a schematic configuration of the in-liquid dissolved matter concentration measuring apparatus 1D according to the present embodiment.

  As shown in FIGS. 6A and 6B, the dissolved substance concentration measuring apparatus 1D in this embodiment includes a light source 32 that emits ultraviolet light, light receiving elements 33a and 33b, a quartz tube 34, and the like. , Optical films 45a and 45b, a light receiving element 36, a reflective element 37, O-rings 8a and 8b, a light shielding member 39, and a housing 40. The quartz tube 34 is longer in length than the quartz tube 4 of the dissolved substance concentration measurement apparatus 1A according to the first embodiment. The light source 32 is, for example, a deep ultraviolet LED light source having a wavelength of 270 nm. The light receiving elements 33a and 33b are, for example, the above-described photo IC diodes.

  In the in-liquid dissolved matter concentration measuring apparatus 1D according to the present embodiment, the optical films 45a and 45b are coating films applied to the quartz tube 34.

  Here, FIG. 6A shows a cross-section of the dissolved substance concentration measuring apparatus 1D in the xy plane passing through the light source 32 and the light receiving elements 33a and 33b, and FIG. 6B shows the light source 32 and the light receiving element. The cross section of the dissolved substance concentration measuring apparatus 1D in the liquid in the yz plane which passes the element 36 and the reflective element 37 is shown.

  As shown in FIGS. 6A and 6B, the in-liquid dissolved matter concentration measurement apparatus 1D according to the present embodiment is particularly an optical member that converts the emitted light of the light source 32 into light in the visible light band or higher. Is the optical films 45a and 45b applied to the quartz tube 34, which is different from the first to third embodiments. Hereinafter, the configuration of the in-liquid dissolved matter concentration measuring apparatus 1D according to the present embodiment will be described.

  The optical films 45a and 45b have an excitation wavelength in the deep ultraviolet wavelength region and an illuminant having an emission wavelength in the visible light wavelength region, or an excitation wavelength in the deep ultraviolet wavelength region, and in the visible light wavelength region. A phosphor having an emission wavelength is included.

  As described above, since the optical members that convert the light emitted from the light source 32 into light in the visible light band or higher are provided as the optical films 45a and 45b applied to the quartz tube 34, in the in-liquid dissolved matter concentration measuring apparatus 1D. A part of the surface of the quartz tube 34 is substituted for the wavelength conversion function. That is, the optical films 45 a and 45 b are provided along the surface of the quartz tube 34. For this reason, the light quantity reduction by the reflection which generate | occur | produces in the entrance plane and exit surface of optical film 45a and 45b can be reduced.

  The optical films 45a and 45b can be formed, for example, by dispersing the phosphor in advance in a fixing agent, applying the phosphor on the surface of the quartz tube 34, and fixing the phosphor by baking or the like. In addition, the formation regions of the optical films 45a and 45b in the quartz tube 34 are set on the surface of the quartz tube 34 facing the light receiving elements 33a and 33b, as shown in FIGS. 6 (a) and 6 (b).

  By adopting the configuration shown in FIGS. 6A and 6B, the quartz tube 34 and the optical films 45a and 45b are integrated with each other without being separated in actual function.

  The phosphor is fixed to the quartz tube 34 by using, for example, SOG (Spin on Glass) or low-melting glass as the phosphor fixing agent, and firing by high-temperature heating (200 ° C. or higher). The method can be adopted. In this case, the jig structure for fixing the phosphor to the quartz tube 34 is not for the plane but for the curved surface.

  The category of integration of the quartz tube 34 and the optical films 45a and 45b includes integration other than that directly adhering to the optical films 45a and 45b on the surface of the quartz tube 34 as described above.

  For example, the phosphor-coated glass coated with the phosphor is used as the optical films 45a and 45b, and the quartz tube 34 and the phosphor-coated glass are bonded with a resin material or welded with a glass-based material. Thus, integration is also included. In this case, the resin material and the glass-based material are materials that do not have a large refractive index difference between the quartz tube 34 and the phosphor-coated glass. Even with such an integrated configuration, it is possible to reduce a light amount decrease due to reflection generated on the entrance surface and the exit surface of the phosphor-coated glass.

[Summary]
1A of dissolved substance density | concentration measuring apparatuses which concern on aspect 1 of this invention are the light source 2 which radiate | emits ultraviolet light, and the conduit | pipe part for allowing the liquid S which has the ultraviolet light absorption characteristic and contains the dissolved substance of a measuring object to pass ( A quartz tube 4), an optical member 5 that emits light from the light source 2 and passes through the conduit portion, and converts the ultraviolet light into a light having a wavelength longer than or equal to the visible light band; and light reception that detects the light that has passed through the optical member 5. An element 3 is provided.

  According to the above configuration, part of the ultraviolet light emitted from the light source 2 is absorbed by the dissolved matter contained in the liquid S in the conduit portion (quartz tube 4), enters the optical member 5, and the optical member In 5, the light is converted into light having a wavelength longer than the visible light band and received by the light receiving element 3. As described above, the light receiving element 3 can be used that receives light having a wavelength higher than the visible light band and having extremely high light receiving sensitivity. That is, it is not necessary to use a light receiving element in the ultraviolet wavelength region with extremely low light receiving sensitivity for the light source 2 that emits ultraviolet light. Therefore, according to the above configuration, it is not necessary to employ a light source having an unnecessarily large energy as the light source 2, and furthermore, when the concentration of dissolved matter is measured with respect to a solution having a low concentration of dissolved matter. However, it becomes easy to secure the amount of light received by the light receiving element 3 necessary for density measurement.

  Therefore, according to said structure, the dissolved concentration in a liquid of the ultraviolet light absorption material which has the light absorption characteristic of an ultraviolet-ray can be measured with a sufficient precision.

The dissolved substance concentration measuring apparatus 1B according to aspect 2 of the present invention is the above-described aspect 1, wherein the light emission range viewed from the light receiving element 3 side of the light source 2 has a radius R centered on the light emission center of the light source 2. The radius R is a method of the light receiving surface of the light receiving element 3 that passes through the center of the light emitting range of the light source 22 with the shortest distance between the light emitting center of the light source and the light receiving element as the distance L. When the angle between the line and the line connecting the normal and the edge of the light emission range of the light source 22 is θ, the following formula (1)
R = Ltanθ (θ ≦ 10 °) Equation 1
The structure shown by may be sufficient.

  According to said structure, when the change of the light reception amount in the light receiving element 3 is converted into a density | concentration, the error resulting from the difference in optical path length can be reduced.

  The liquid dissolved matter concentration measuring apparatus 1C according to the third aspect of the present invention includes the two light receiving elements 33a and 33b in the first or second aspect, and the two light receiving elements 33a and 33b receive the light reception from the light source 32. The optical paths A and B reaching the elements 33a and 33b may be arranged so as to intersect at different angles with respect to the conduit portion (quartz tube 34).

  According to the above configuration, the dissolved concentration of the dissolved substance can be converted and calculated based on the ratio of the received light amounts I1 and I2 received by the light receiving elements 33a and 33b. That is, for the conversion calculation of the dissolved concentration of the dissolved matter, there is no need for the amount of light that the light emitted from the light source 32 reaches the light receiving elements 33a and 33b when there is no dissolved matter in the liquid S. Therefore, according to the above configuration, the conversion calculation for measuring the dissolved concentration can be performed stably.

  The liquid dissolved matter concentration measuring apparatus 1C according to the fourth aspect of the present invention receives the received light amounts of the two light receiving elements 33a and 33b as signals in the third aspect, and receives the received light amounts of the two light receiving elements 33a and 33b. It is preferable that a measurement circuit 33c that outputs a logarithmic value of the ratio as a signal is mounted.

  By using such a measurement circuit 33c, the signal processing accuracy of the circuit for concentration measurement is also improved. As a result, according to said structure, the reliability of the measured value of dissolved substance concentration also increases.

  1A of dissolved substance density | concentration measuring apparatuses which concern on aspect 5 of this invention are the said liquid S and said liquid part in said aspect 1-4 whose cross-sectional shape is an annular | circular shape. The refractive index difference is preferably less than 0.1.

  According to said structure, since the cross-sectional shape of the said conduit part (quartz tube 4) is an annular shape, when the liquid S flows into the said conduit part and the said conduit part is satisfy | filled with the liquid S, from the light source 2, Due to the refracted light effect of the emitted light and the conduit section and the liquid S, the ratio of the light component reaching the light receiving element 3 out of the light emitted from the light source 2 is increased, and the light source 2 reaches the light receiving element 3. The radiation range of the light to be spread will be expanded. Therefore, according to the above configuration, it is possible to increase the amount of light reaching the light receiving element 3 from the light source 2 while maintaining the variation in the optical path length within a small range. As a result, the difference in the amount of light received by the light receiving element 3 due to the absorption of the dissolved matter, which is important in the dissolved matter concentration measurement, can be detected by increasing it.

  Further, according to the above configuration, since the difference in refractive index with the liquid S is less than 0.1, the reflection of light at the boundary between the liquid S and the conduit portion is greatly reduced. Therefore, the effect of increasing the amount of light reaching the light receiving element 3 from the light source 2 is further improved.

  1A of dissolved substance density | concentration measuring apparatuses which concern on aspect 6 of this invention are the transmission member which permeate | transmits the light of the wavelength beyond the said visible light band in the said aspects 1-5, and an excitation wavelength in the deep ultraviolet wavelength range. A fluorescent material having an emission wavelength in the visible light wavelength range, and the fluorescent material may be included in the transmissive member or formed on the surface of the transmissive member.

  Thereby, the measurement precision of a dissolved substance density | concentration can be stabilized for a long period of time.

  The dissolved substance concentration measurement apparatus 1D according to Aspect 7 of the present invention is the Aspect 1-6, wherein the optical member (optical films 45a and 45b) is integrated with the surface of the conduit portion (quartz tube 34). It is preferable to be provided.

  According to said structure, the light quantity reduction by the reflection which generate | occur | produces in the entrance plane and exit surface of the said optical member can be reduced.

  1A of dissolved substance concentration measuring apparatuses which concern on aspect 8 of this invention monitor the light quantity at the time of the light emission of the said light source 2 in the said light source 2 side in the said conduit | pipe part (quartz tube 4) in the said aspects 1-7. And a reflection element 7 for guiding the light emitted from the light source 2 to the light reception element 6. The reflection element 7 converts the light emitted from the light source 2 into light having a wavelength longer than the visible light band. The structure which converts and reflects to the light receiving element 6 may be sufficient.

  According to the above configuration, part of the ultraviolet light emitted from the light source 2 first enters the reflective element 7. Then, the light is converted into light having a visible band or higher by the reflecting element 7 and then reflected and received by the light receiving element 6. In this way, by converting a part of the ultraviolet light emitted from the light source 2 into light in the visible light band or more and receiving it by the light receiving element 6, the light quantity at the time of light emission of the light source 2 can be monitored. And by monitoring the light quantity at the time of the light emission of the light source 2, the influence of the fall of the emitted light quantity of the light source 2 at the time of a measurement can be prevented.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be used for a measuring instrument that measures the dissolved concentration of an ultraviolet light absorbing material in a liquid, for example, the ozone concentration in ozone water.

1A, 1B, 1C, 1D Dissolved substance concentration measuring device 2, 22, 32 Light source 3, 33a, 33b, Light receiving element 4, 34 Quartz tube (conduit portion)
5, 35a, 35b Optical member 45a, 45b Optical film

Claims (7)

A light source that emits ultraviolet light;
A conduit portion for passing a liquid containing dissolved substances to be measured, having ultraviolet light absorption characteristics;
An optical member that emits from the light source and converts ultraviolet light that passes through the conduit portion into light having a wavelength longer than or equal to the visible light band;
And a light receiving element for detecting light that has passed through the optical member. The light emission range viewed from the light receiving element side of the light source is a range within a circular region having a radius R centered on the light emission center of the light source, and the radius R is a distance between the light emission center of the light source and the light receiving element. An angle formed by a normal line of the light receiving surface of the light receiving element passing through the center of the light emission range of the light source and a line connecting the normal line and the edge of the light emission range of the light source is defined as θ. The following formula (1)
R = Ltanθ (θ ≦ 10 °) Equation 1
The dissolved substance concentration measuring apparatus in liquid according to claim 1, characterized by: With two light receiving elements,
The two light receiving elements are arranged such that optical paths reaching the light receiving element from the light source intersect at different angles with respect to the conduit portion. The dissolved substance concentration measuring apparatus of description.   4. The measurement circuit according to claim 3, further comprising: a measurement circuit that inputs light reception amounts of the two light receiving elements as signals and outputs a logarithmic value of a ratio of light reception amounts of the two light receiving elements as signals. 5. Dissolved substance concentration measuring device in liquid.   The liquid according to any one of claims 1 to 4, wherein the conduit portion has an annular shape in cross section, and a difference in refractive index from the liquid is less than 0.1. Middle dissolved substance concentration measuring device. The optical member includes a transmission member that transmits light having a wavelength longer than or equal to the visible light band, and a fluorescent material having an excitation wavelength in the deep ultraviolet wavelength region and an emission wavelength in the visible light wavelength region,
The said fluorescent material is contained in the said permeable member, or is formed in the surface of the said transmissive member, The dissolved substance concentration measuring apparatus in any one of Claims 1-5 characterized by the above-mentioned. .   The said optical member is integrally provided in the surface of the said conduit | pipe part, The dissolved substance concentration measuring apparatus in any one of Claims 1-6 characterized by the above-mentioned.

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