JPH1137940A - Water quality measuring unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive water quality measuring unit excellent in portability in which the quality of an unspecified liquid can be measured easily. SOLUTION: A light passed through a liquid to be measured is converted through a photodiode at an optical section 4 into an electric signal which is then processed at a control section 11 in order to indicate the quality of the liquid to be measured. Since the measuring unit body 1 comprising the optical section 4 and the control section 11 can be assembled independently, an inexpensive product can be provided. The measuring unit body 1 is excellent in portability and can be carried to an arbitrary place. Since a cell for containing a liquid to be measured can be mounted removably on the outside of the measuring unit body 1 from the optical section 4, the liquid to be measured can be set or removed easily and the quality of an unspecified liquid can be measured easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality measuring instrument suitable for measuring water quality of a liquid to be measured, for example, measuring COD (chemical oxygen demand).

[0002]

Generally, as this type of water quality measuring device, a device incorporating an analytical method specified in JIS-K0102 has been conventionally known. This is because COD is determined by sufficiently heating and reacting potassium permanganate added in advance in a quantitative excess with an organic substance present in the liquid to be measured, and then quantifying the remaining potassium permanganate by coulometric titration. The value is measured. This measurement method based on the JIS standard allows accurate COD values to be known, but on the other hand, it is difficult to manage reagents because it is difficult to know how much reagents are required according to the turbidity of the liquid to be measured. is there. Also, for example, when performing daily water quality management of a pool or the like, it takes about two to three days until the measurement result is determined by an external analysis request, and fluctuations in water quality during this time cannot be grasped. There were inconveniences such as throwing in more than necessary.

On the other hand, Japanese Patent Publication No. 53-36356 and Japanese Utility Model Laid-Open Publication No. 3-85562 disclose a water quality measuring instrument which does not rely on the above-mentioned chemical method and detects ultraviolet light passing through a liquid to be measured from a light source. To an electrical signal
There is disclosed a device that compares and calculates this signal to measure a COD value in real time. With such an optical method, there is no need to manage reagents, and measurement can be easily performed without requiring days. However, as disclosed in the former publication, this type of water quality measuring instrument is incorporated in a plant such as in the middle of an industrial drainage channel, and is therefore unsuitable for portable use, expensive, and unspecified. The water quality of the measurement liquid cannot be measured.

In view of the above problems, an object of the present invention is to provide an inexpensive and highly portable water quality measuring instrument which can easily measure the water quality of an unspecified liquid to be measured.

[0005]

The water quality measuring instrument of the present invention comprises:
In order to achieve the above object, an optical unit that converts light passing through a liquid to be measured from a light source into an electric signal by a detector, and performs an arithmetic processing on an output from the optical unit to display a water quality of the liquid to be measured. The control section is provided on the independently movable measuring instrument main body, and a cell for containing the liquid to be measured is detachably provided on the optical section from outside the measuring instrument main body.

[0006] According to the above configuration, the measuring device main body can be assembled independently without considering the configuration on the plant side, so that the product can be provided at low cost. Further, the measuring device main body including the optical unit and the control unit can be carried to an arbitrary place, and is excellent in portability. Further, since the cell can be attached to and detached from the measuring instrument body from the optical section, the liquid to be measured can be easily taken in and out, and the water quality of the unspecified liquid to be measured can be easily measured.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the water quality measuring device according to the present invention will be described below with reference to FIGS. First, the overall configuration will be described with reference to FIGS. 1 to 3. Reference numeral 1 denotes a box-shaped measuring device main body that forms an outer shell of a water quality measuring device, except for a rising portion 2A formed in a peripheral portion. The bottom plate 2 includes a substantially flat bottom plate 2 and a cover 3 whose lower opening is closed by the bottom plate 2. In this embodiment,
Although the cover 3 having a predetermined shape is formed by pressing a metal plate, the cover 3 may be formed of a resin for weight reduction. An opening 5 is formed on the upper surface of the cover 3 so as to face the optical unit 4 provided in the measuring instrument main body 1, and an inclined portion 6 is formed on the upper front surface of the cover 3. Inclined part 6
A display unit 7 composed of a dot matrix type LCD (liquid crystal display) capable of displaying various kinds of information such as a soft display, and an operation unit 8 having a plurality of switches mounted on a switch board (not shown) are provided inside. The display unit 7 and the panel sheet 9 of the operation unit 8 are attached to the outer surface of the inclined unit 6. The reason why the operation section 8 having various switches is disposed on the inclined section 6 on the front surface of the cover 3 is to improve operability during use. Further, in consideration of the fact that the measuring instrument main body 1 is a device that handles liquid, the intrusion of liquid into the display unit 7 and the operation unit 8 is prevented by using the panel sheet 9 having a drip-proof effect. The measuring device main body 1 can be moved independently of other devices and plants. Thereby, the measuring device main body 1 can be carried to an arbitrary place. In addition, 10 is a rubber leg which is attached and fixed to the four corners of the bottom plate 2.

Inside the measuring instrument body 1, in addition to the optical unit 4, a control unit 11 for calculating the output from the optical unit 4 and displaying the water quality of the liquid to be measured is provided. This control unit 11
Is a control board 13 arranged at intervals on the bottom plate 2 by the spacers 12 together with the display unit 7 and the operation unit 8 described above,
A power supply board 15 is provided below the control board 13 and is also arranged on the bottom plate 2 with an interval by another spacer 14. Although not shown, the control board 13 includes a clock device, a storage device such as a ROM and a RAM, and an A / D converter and a D / A converter in addition to a control device and an arithmetic device that constitute a known microprocessor. It has an input / output device. The power supply board 15 supplies a predetermined operating voltage not only to the control section 11 but also to the optical section 4, and mounts a power switch 16 mounted on the rising portion 2A of the bottom plate 2.

The optical section 4 includes a low-pressure mercury lamp 21 as a light source.
(See FIG. 5); a lower block member 23 provided adjacent to the lamp holder 22 for setting an optical axis from the low-pressure mercury lamp 21;
The upper block member 24 is screwed and fixed to the upper part of the cover 3 and is provided so that the upper part is exposed to the opening 5 of the cover 3.
And a lid member 25 that covers the upper part of the upper block member 24 so as to be openable and closable.
And a preamplifier board 26 electrically connected to the control unit 13 at the subsequent stage. In this, the lower block member
23 is mounted on a preamplifier substrate 26. The preamplifier substrate 26 is mounted such that the lower block member 23 and the upper block member 24 are placed as close as possible to the upper surface of the cover 3 by a support member (not shown). Provided at height. On the back side of the upper block member 24, a shaft 27 connected to the lid member 25 is provided. The lid member 25 is rotatably provided around the shaft 27 as a center of rotation.

On the upper surface of the upper block member 24, a cell accommodation hole 32 for accommodating a cylindrical cell 31 with a bottom is formed. The cell receiving hole 32 is formed in the lower block member 23.
The cell accommodating holes 32 and 33 constitute a cell accommodating portion of the optical section 4. Then, the lid member 25 is opened, and the cell 31 is inserted from above the outside of the measuring instrument main body 1 into the cell accommodating hole 3.
When inserted into the cells 2 and 33, the cells 31 are accommodated in the cell accommodation holes 32 and 33, and the lid member 25 can be closed in this state. When the lid member 25 is in the closed state, the lid member 25 is attached to the upper end of the convex portion 34 of the upper block member 24 formed around the cell accommodation hole 32.
Of the cover 3 is prevented from entering the cell 31 through the opening 5 of the cover 3. The upper block member 24
Protruding part 34 protruding from the opening 5 side
Is provided in view of the fact that it is a device that handles liquids. That is, the convex portion 34 prevents liquid from entering the optical section 4 from the cell receiving holes 32 and 33. Around the lower block 23, a light-shielding tape 35 for preventing outside light from entering is wound.

The cell 31 accommodates the liquid to be measured, and may have various shapes.
As shown in FIG. 4, it is composed of a transparent cylindrical body 36 having an inner diameter of 10 mm and an outer diameter of 12 mm, and a detachable lid 37 which covers the bottom opening of the body 36 in a sealed state. The body 36 has an advantage that it can be easily formed only by cutting a cylindrical pipe into a predetermined length, and can be manufactured at a lower cost than a square one.
Further, the inner surface of the body 36 having no corners can be easily cleaned only by opening the lid 37. The lid 37 is made of a translucent elastic member such as silicon. When the lid 37 is inserted into the body 36, the inserted portion is fitted and deformed. The body 36 through which the light of the low-pressure mercury lamp 21 passes,
It is preferable that the member is not affected by ultraviolet rays, such as quartz glass. Preferably, the surface of the body 36 is polished so that the dimensional error is within ± 0.1 mm. When such surface polishing is performed, there is an advantage that irregular reflection on the surface is reduced, light absorption by the cell 31 is reduced, and light output passing through the cell 31 is increased. The dimensional error can be suppressed to about ± 0.05 mm by the surface polishing, but the above-mentioned ± 0.1 mm is most preferable in consideration of cost. In addition, in order to facilitate the alignment when the cell 31 is mounted in the cell receiving holes 32 and 33, the upper end of the body 36 is provided with
A positioning groove 38 is formed. Also, the upper block member
A projection 39 is also formed on the convex portion 34 of the cell 24 toward the cell accommodation hole 32, and by aligning the projection 39 with the groove 38 of the cell 31, the mounting position of the cell 31 is reproducible. ing.
A tape with a positioning line may be wound around the body 36 instead of the groove 38. However, since the cell 31 handles liquid, the tape is soiled or peeled off, which is inconvenient. Therefore, in order to improve the usability of the cell 31, the groove 38 as in this embodiment is required.
Is preferably formed.

Next, the configuration of the optical unit 4 will be described in particular with reference to FIG.
This will be described with reference to FIG. In the same figure, the lower block member 23
From the low-pressure mercury lamp 21 to the cell receiving hole 33 and thus the cell 31
And a light path from the low-pressure mercury lamp 21 that is branched from the sample-side optical path 42 and passes through the cell 31 before passing through the cell 31. A reference side optical path 44 leading to a photodiode 43 which is a reference side detector for detection is formed. As described above, by forming the sample-side optical path 42 for detecting light after passing through the cell 31 and the reference-side optical path 44 for detecting light before passing through the cell 31, in the single lower block member 23. The cost is reduced by downsizing the measuring instrument body 1 and using common parts. Although the outer shape of the lower block member 23 is box-shaped, concave portions 45 and 46 are formed in portions where the lead pins 41A and 43A of the photodiodes 41 and 43 project. This recess 45,
By means of 46, when lead wires (not shown) are soldered to the lead pins 41A and 43A, the lead wires do not protrude outside the box-shaped lower block member 23, and the measuring instrument main body 1 can be downsized. Further, there is no projecting portion of the lead pins 41A and 43A around the lower block member 23, so that the light shielding tape 35 can be easily wound. The lower block member 23 and the upper block member 24 are formed by molding a resin member such as POM or ABS with a mold, but need not be a block structure. In short, a shape suitable for resin molding is preferable because cost reduction by molding can be achieved. Reference numeral 47 denotes a hole for fixing the upper block member 24 into which the screw 48 is screwed.

Reference numeral 51 denotes a stop member for stopping the light of the low-pressure mercury lamp 21. The stop member 51 has a light path 42 on the sample side.
A pinhole is formed in line with the optical axis of. Reference numeral 52 denotes a half mirror. Here, the reference-side optical path 44 branches from the sample-side optical path 42. Numeral 53 denotes an interference filter which selectively transmits ultraviolet light having a wavelength of 254 nm, which is preferably provided immediately before the photodiode 41 provided on the sample side optical path 42 as in this embodiment. The reason is,
For example, if the interference filter 53 is disposed in front of the cell 31, the external light is detected by the photodiode 41 as it is, and the influence of the external light upon measurement increases. When the interference filter 53 is arranged as in the present embodiment, even if external light enters the optical unit 4, the light is blocked by the interference filter 53 immediately before the photodiode 41, and the measurement accuracy is improved. At this time, only the ultraviolet wavelength component included in the external light passes through the interference filter 53. However, the influence of the ultraviolet wavelength component is small in sunlight or general indoor lighting, and the opening / closing state of the lid member 25 has little effect. Therefore, the cover member 25 that covers the upper part of the cell 31 also does not require a strict light-shielding structure, and the cost and size of the measuring instrument main body 1 can be reduced. When light passing through the interference filter 53 reaches the photodiode 41, the photodiode 41
Is an electric signal corresponding to the detected light.
Output to At this time, even when the light beam on the sample side optical path 42 contains the liquid to be measured in the cell 31, the photodiode
It is preferable not to protrude from the 41 effective light receiving surface. As a result, the cell blank value (measured value when the cell 31 is mounted in an empty state and the value when the purified water is stored in the cell 31 is set to zero) can be kept within a certain value, and the measurement accuracy can be improved. it can.

On the other hand, another filter 55 is provided in the reference side optical path 44 immediately before the photodiode 43. Since this filter 55 does not pass through the liquid to be measured in the cell 31,
There is no need to capture a specific wavelength (ultraviolet light). Therefore, it is preferable to use an inexpensive bandpass filter. Also,
When a bandpass filter is used, the transmission band is widened and the amount of light received by the photodiode 43 is greatly increased, so that the S / N ratio on the reference side can be improved. Further, the filter 55 has an effect of removing unnecessary noise components. Further, as in the present embodiment, it is preferable that the photodiode 43 on the reference side be provided at a position that does not face the low-pressure mercury lamp 21. The reason is to prevent noise from being superimposed on the photodiode 43 on the reference side from a D / D converter (not shown) for driving the low-pressure mercury lamp 21 mounted on the preamplifier substrate 26. In this embodiment, since the photodiode 43 is incorporated in the lower block member 23, there is an advantage that the mounting position of the photodiode 43 can be easily changed by resin molding of the lower block member 23. When the light passing through the filter 55 reaches the photodiode 43, the photodiode 43 outputs an electric signal corresponding to the detected light to the preamplifier substrate 26.

FIG. 6 is a block diagram showing the electrical configuration. In the figure, a preamplifier substrate 26 includes amplifiers 61 and 62 connected to the photodiodes 41 and 43, respectively.
It has. Each of the amplifiers 61 and 62 includes a photodiode 4
The detection signals 1 and 43 are amplified and output to the A / D converters 63 and 64 of the control board 13 constituting the control unit 11. Then, the digital signals converted by the A / D converters 63 and 64 are taken into a microcomputer (hereinafter referred to as a microcomputer) 65. On the input side of the microcomputer 65, a set value switch 66 constituting the operation unit 8 and a zero adjustment switch
67, a measurement switch 68, and a setting item switch 69 are connected respectively. Then, based on the operation signals of these switches 66 to 69, the microcomputer 61
The light intensity I on the sample side detected at 41 and the photodiode 43
After the comparison with the reference side light amount Io detected in the above, arithmetic processing is performed, and the display unit 7 displays the water quality of the liquid to be measured.

The microcomputer 61 measures the time after the power is turned on, or monitors the fluctuation of the detection output from the photodiodes 41 and 43 as a control sequence of a program held by the microcomputer 61 to determine whether the measurement is possible. A measurability determining means 71 for determining whether or not the
Zero adjustment control means 72 for setting, as a reference value, the detection output from photodiodes 41 and 43 when purified water is contained in
And a water quality measurement control means 73 for measuring the water quality of the liquid to be measured contained in the cell 31 based on a relative value to the reference value set by the zero adjustment control means 72. Among them, the measurable determination means 71 is provided to remove fluctuations in the detection outputs from the photodiodes 41 and 43 due to a temperature drift immediately after the power is turned on. This temperature drift can be eliminated to some extent by designing the circuit of the preamplifier board 26 independently.However, a high level of technology is required in the circuit design, different components are required, and
Since it takes time to adjust the preamplifier board 26, this is a major factor in cost increase. Therefore, it is preferable to incorporate the measurable determination means 71 into the microcomputer 65 of the control unit 11 as in the present embodiment.

The measurability judging means 71 of this embodiment is configured so that the output voltage of the preamplifier board 26 is measured by the microcomputer 65, and when the change is within a certain range, the measurement is possible. Specifically, the photodiode 43 on the reference side
The output voltage from is monitored every predetermined time (30 seconds), and when the difference between the previous measured value and the current measured value falls within the predetermined value (0.5%), measurement is enabled. In this regard, if the standby time after the power is turned on can be variably set and the measurement is performed after the set standby time has elapsed, it is difficult for the user to determine how much the measurement can be performed. There is a concern that the system will be used with the waiting time set as is. However, according to the present embodiment, whether measurement is possible or not depends on the output voltage from the photodiode 43, so that measurement can be made in a preferable state. In particular, the photodiode 43
Is received by the light from the reference side optical path 44. Therefore, even if the cell 31 is attached or detached immediately after the power is turned on, the output voltage is not affected and the measurable state can be accurately determined.

In this embodiment, the zero adjustment control means 72 is further provided in order to avoid the influence of the temperature drift after the measurement is possible. The zero adjustment by the zero adjustment control means 72 is performed by pushing the zero adjustment switch 67. The measurement of water quality by the water quality measurement control means 73 is performed by pushing the measurement switch 68. When the set value switch 66 is pushed, the setting mode is selected instead of the measurement mode. In the initial state of the setting mode, the setting mode of the coefficient is displayed on the display unit 7. Each time the setting item switch 68 is pushed and operated in the normal measurement mode, the display on the display section 7 displays the COD value indicating the COD value of the liquid to be measured and the potassium permanganate value of the liquid to be measured. KMnO ₄
The display switches. Each time the setting item switch 68 is pressed in the setting mode, a display of a coefficient k to be applied to the measurement data, a display of a correction value of the coefficient k,
The display of the value or the potassium permanganate value and the display of the power supply frequency area (50 Hz / 60 Hz) are sequentially performed.
Then, the coefficient k, its correction value, COD display and KM
The switching of the nO ₄ display and the switching of the power supply frequency area can be performed by pressing the zero adjustment switch 67 and the measurement switch 68.

When the COD display is selected by operating the operation unit 8, the microcomputer 65 calculates the COD value of the liquid to be measured contained in the cell 31 based on the following equation.

[0020]

(Equation 1)

Where N and n are the number of measurements,
k is the coefficient, Io is the reference-side light amount, and I is the sample-side light amount. In this embodiment, the operation unit 8
The coefficient k can be variably set to 0.1 and the correction value can be set to one at a time.

Next, the operation of the water quality measuring device having the above configuration will be described with reference to the flowchart of FIG. The display mode of the display unit 7 described below can be arbitrarily changed. In step S1, when the power switch 16 is turned on, a predetermined operating voltage of the control unit 11 and the optical unit 4 is supplied from the power supply board 15. Then, in response to a command from the microcomputer 65, the control unit 11 displays "Standby" on the display unit 7 to indicate that it is on standby (step S2). Then, step S
In step 3, if the low-pressure mercury lamp 21 serving as the light source is determined to be in a stable state by the measurable determination means 71, the process proceeds to the next step S4, where it is determined that measurement is possible and zero adjustment needs to be performed. The display “Kano Zero Adj” is performed on the display unit 7.

The zero adjustment is performed by aligning the groove 38 of the cell 31 containing purified water in advance with the projection 39 of the upper block member 24.
The cell 31 is mounted in the cell receiving holes 32 and 33 of the optical unit 4, and the cover member
Close 25. Then, in step S5, the push operation of the zero adjustment switch 67 is performed. After the light of the low-pressure mercury lamp 21 passes through the cell 31 and the interference filter 53 and reaches the photodiode 41 on the sample side, the photodiode 41
The detection output converted into an electric signal by the above is amplified by the amplifier 61, converted into a digital signal by the A / D converter 63, and taken into the microcomputer 65. The light that has reached the reference-side photodiode 43 without passing through the cell 31 by the half mirror 53 is converted into an electric signal here, the detection signal is amplified by the amplifier 62, and the A / D converter is used. The signal is converted into a digital signal by 64 and is taken into the microcomputer 65. The zero adjustment control means 72 of the microcomputer 65 sets the digital signal fetched from the A / D converter 63 as a reference value while referring to the digital signal fetched from the A / D converter 64, and adjusts the cello on the display unit 7. Is displayed (step S6). Specifically, when the COD display is selected, a display of “COD 0.0 mg / l” is performed, and when the KMnO ₄ display is selected,
The display reads "KMnO4 0.0 mg / l". This zero adjustment can be performed during the subsequent measurement.
It is configured so that it can be arbitrarily executed by pushing the 67. Thus, even if the measurement is performed for a long time, the influence of the above-described temperature drift can be minimized. After the zero adjustment, the lid member 25 is opened, the cell 31 is taken out, and the purified water is emptied.

The water quality of the liquid to be measured is measured in the empty cell 31.
The liquid to be measured is stored, and the cell 31
While aligning the groove 38 with the protrusion 39 of the upper block member 24,
The lens 31 is attached to the cell receiving holes 32 and 33 of the optical section 4, and the lid member 25 is
Close. Then, in step S7, the measurement switch
Pushing the switch 68. Water quality measurement control means 73 of microcomputer 65
Are the digital signals captured from the A / D converters 63 and 64
Based on the signal, the reference value set by the zero adjustment control means 72 and
Of the liquid to be measured contained in the cell 31 by the relative value of C
Measured as OD value or potassium permanganate value,
Is displayed on the display unit 7 (step
Step S8). At this time, if COD display is selected,
Displays “COD ****. * Mg / l”.
KMnO ₄When the display is selected, “KMnO4
 ***. * Mg / l "is displayed. In addition, here
"****. *" Is a measured value. Measurement completed
Take out the cell 31 from the cell receiving holes 32 and 33 of the optical unit 4
Then, the lid member 25 is closed and the power switch 16 is turned off.

As described above, according to the present embodiment, the optical unit 4 for converting the light passing through the liquid to be measured from the low-pressure mercury lamp 21 as the light source into the electric signal by the photodiode 41 as the detector, and this optical unit And a control unit 11 for displaying the water quality of the liquid to be measured by arithmetically processing the output from the measuring unit 4 in the independently movable measuring instrument main body 1 and a cell 31 for containing the liquid to be measured is connected to the measuring instrument main body. 1 is provided detachably from the optical unit 4 from the outside. Therefore, unlike a water quality measuring instrument incorporated in a conventional plant or the like, the measuring instrument main body 1 can be assembled independently without considering the configuration on the plant side, so that products can be provided at low cost. Further, the measuring device main body 1 including the optical unit 4 and the control unit 11 can be carried to an arbitrary place, and is excellent in portability. Furthermore, since the cell 31 can be attached to and detached from the optical unit 4 to the outside of the measuring instrument main body 1, the liquid to be measured can be easily taken in and out, and the water quality of the unspecified liquid to be measured can be easily measured.

In such a configuration, in this embodiment, the optical path from the low-pressure mercury lamp 21 as the light source to the photodiode 41 as the detector, that is, the sample-side optical path 42
However, the lower block member 23 is a single member. By doing so, it is possible to reduce the cost by downsizing the optical section 4 and thus the measuring instrument main body 1 and using common components. Further, in the present embodiment, a reference-side optical path 44 branched from the sample-side optical path 42 and reaching a photodiode 43 that is a reference-side detector that detects the amount of light from the low-pressure mercury lamp 21 before passing through the cell 31.
Are also formed on the same lower block member 23. For this reason, the measuring device main body 1 can be provided without providing a separate member for each of the optical paths 42 and 44.
It is possible to further promote the cost reduction by downsizing and common use of parts. In addition to the fact that the photodiodes 41 and 43 are incorporated in the box-shaped lower block member 23 and the concave portions 45 and 46 are formed in the portions of the photodiodes 41 and 43 where the lead pins 41A and 43A protrude, respectively. The main body 1 can be downsized. In order to reduce the cost of processing the parts of the lower block member 23, it is preferable to mold the resin member with a mold as described above.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, the light source is not limited to the low-pressure mercury lamp in the embodiment. Also, various light receiving elements other than the photodiode can be used for the detector.

[0028]

The water quality measuring instrument of the present invention comprises: an optical unit for converting light passed from a light source through a liquid to be measured into an electric signal by a detector; And a control unit for displaying the water quality of the measuring instrument main body provided independently and movable, and a cell containing the liquid to be measured is provided detachably from the outside of the measuring instrument main body to the optical unit. In addition, it is possible to provide an inexpensive and highly portable water quality measuring device that can easily measure the water quality of an unspecified liquid to be measured.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a water quality measuring instrument according to an embodiment of the present invention with a cover member opened.

FIG. 2 is an overall perspective view showing a state in which the upper lid member is closed and a cover is removed.

FIG. 3 is a plan view of the optical unit in a state where the upper lid member is opened.

FIG. 4 is a front view of the cell.

FIG. 5 is a plan view of a main part of the optical unit.

FIG. 6 is a block diagram showing an electrical configuration of the same.

FIG. 7 is a flowchart showing an operation procedure of the same.

[Explanation of symbols]

 1 Measuring instrument body 4 Optical section 11 Control section 21 Low-pressure mercury lamp (light source) 31 Cell 41 Photodiode (detector)

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[Procedure amendment]

[Submission date] July 30, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

FIG. 6 is a block diagram showing the electrical configuration. In the figure, a preamplifier substrate 26 includes amplifiers 61 and 62 connected to the photodiodes 41 and 43, respectively.
It has. Each of the amplifiers 61 and 62 includes a photodiode 4
The detection signals 1 and 43 are amplified and output to the A / D converters 63 and 64 of the control board 13 constituting the control unit 11. Then, the digital signals converted by the A / D converters 63 and 64 are taken into a microcomputer (hereinafter referred to as a microcomputer) 65. On the input side of the microcomputer 65, a set value switch 66 constituting the operation unit 8 and a zero adjustment switch
67, a measurement switch 68, and a setting item switch 69 are connected respectively. Then, based on the operation signals of these switches 66 to 69, the microcomputer 65
The light intensity I on the sample side detected at 41 and the photodiode 43
After the comparison with the reference side light amount Io detected in the above, arithmetic processing is performed, and the display unit 7 displays the water quality of the liquid to be measured.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The microcomputer 65 measures the time after turning on the power or monitors the fluctuation of the detection output from the photodiodes 41 and 43 as a control sequence of a program held by the microcomputer 65 to determine whether the measurement is possible. A measurability determining means 71 for determining whether or not the
Zero adjustment control means 72 for setting, as a reference value, the detection output from photodiodes 41 and 43 when purified water is contained in
And a water quality measurement control means 73 for measuring the water quality of the liquid to be measured contained in the cell 31 based on a relative value to the reference value set by the zero adjustment control means 72. Among them, the measurable determination means 71 is provided to remove fluctuations in the detection outputs from the photodiodes 41 and 43 due to a temperature drift immediately after the power is turned on. This temperature drift can be eliminated to some extent by designing the circuit of the preamplifier board 26 independently.However, a high level of technology is required in the circuit design, different components are required, and
Since it takes time to adjust the preamplifier board 26, this is a major factor in cost increase. Therefore, it is preferable to incorporate the measurable determination means 71 into the microcomputer 65 of the control unit 11 as in the present embodiment.

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshiyuki Abe 3918-2 Akashiru, Maki-cho, Nishikanbara-gun, Niigata Prefecture Maruzen Seiki Kogyo Co., Ltd.

Claims (1)

[Claims] 1. An optical unit for converting light passing through a liquid to be measured from a light source into an electric signal by a detector, a control unit for performing an arithmetic processing on an output from the optical unit and displaying a water quality of the liquid to be measured. A water quality measuring instrument, wherein a cell for containing the liquid to be measured is detachably attached to the optical unit from outside the measuring instrument main body.