JPH08128955A - Gas concentration meter inspection method and gas concentration meter - Google Patents

Abstract

PURPOSE: To provide a gas densitometer inspection method capable of conducting without use of a sample gas and provide a gas concentration meter capable of performing self-diagnosis and automatic calibration by using the inspection method. CONSTITUTION: From a light source 18, first light having regular quantity of light and second light equivalent to light obtained when the first light is transmitted through gas containing a specified concentration of a substance being measuring are irradiated in a cell 14 in which gas containing no substance being measuring is filled, and intercepted with a photoelectric tube 19. Each intercepted light is converted into an electric signal corresponding to the light intensity with the sensor 19, amplified with an amplifier 20, then converted into a digital signal with an A/D converter 21. Two values of the first light and the second light are operated with an operation part 11, and concentration is obtained. The concentration obtained is compared with the specified concentration which prescribes the quantity of light of the second light to obtain the accuracy of a concentration meter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a gas concentration meter such as an ozone (O ₃ ) concentration meter for measuring the concentration of a predetermined substance in a sample gas based on the amount of transmitted light, and the inspection method. The present invention relates to a gas concentration meter that can be self-diagnosed by a method or can be automatically calibrated.

[0002]

2. Description of the Related Art There is a method of measuring the concentration of a gas to be measured in a sample gas by utilizing an optical absorption spectrum peculiar to gas molecules. The method is to irradiate the sample gas with light having a wavelength close to the peak value of the absorption curve of the gas to be measured, measure the amount of light transmitted through the sample gas, and use the Lambert-Beer law based on the amount of transmitted light. Is used to calculate the concentration of the gas to be measured.

An example of such a gas densitometer is an ozone densitometer. The configuration is to measure the ozone concentration of the sample gas by irradiating the sample gas containing ozone and the reference gas not containing ozone with the same amount of light and comparing the amount of light that has passed through those gases. is there. Ultraviolet light having a wavelength close to the maximum light absorption coefficient of ozone is used as the irradiation light. Further, the transmitted light is converted into an electric signal by using a photoelectric tube and signal processing is performed. The electric signal is amplified by an amplifier, quantized by an A / D converter, and the quantized data is calculated by a digital calculator to obtain and display the concentration.

[0004]

However, in a gas densitometer for measuring the concentration of a gas such as ozone, which is easily decomposed, it is necessary to inspect whether or not the measurement is accurately performed, and to confirm and adjust the accuracy. There was a problem that it was difficult.
This is because unstable gas such as ozone is immediately decomposed and cannot be stored stably, so that it is practically impossible to generate a gas having a known concentration as a standard for inspection. In order to generate ozone gas of known concentration, it is necessary to adjust the ozone generator by measuring the concentration of ozone gas generated by the ozone generator with an ozone densitometer. However, this method cannot be a solution because it requires an ozone concentration meter that can accurately measure the ozone concentration. Therefore, the operation of the gas densitometer cannot be comprehensively inspected, and it is difficult to calibrate the generated error. Further, gas concentration meters such as ozone gas having a self-diagnosis function and an automatic calibration function have not been put into practical use until now.

The following method has been proposed as a method for inspecting, diagnosing, and calibrating the above-described gas concentration meter without using a gas containing a substance to be measured. This is a method in which an optical filter is inserted in the optical path while the light incident on the reference gas is emitted and received by the phototube, and the amount of transmitted light is reduced to a predetermined value. As a result, the subsequent signal processing circuits, that is, the phototube, the amplifier, the A / D converter, and
It is possible to comprehensively check the operation of the arithmetic unit. However, this method has a problem in that the filter needs to be installed with high precision and the mechanism is precise and complicated. Further, the filter itself also changes the amount of light transmission due to the adhesion of dust and the change over time, and as a result, the accuracy cannot be maintained to the extent that the self-diagnosis and automatic calibration can be performed.

As described above, in a gas concentration meter for ozone or the like, the operation and accuracy cannot be properly inspected, and self-diagnosis and calibration cannot be performed, so that there is a problem that it is difficult to accurately measure the gas concentration. It was

Accordingly, it is an object of the present invention to provide a method for inspecting the operation and accuracy of a gas concentration meter without actually using a gas containing a substance to be measured. Another object of the present invention is to provide a gas densitometer capable of comprehensively diagnosing the operation of the gas densitometer by the above method. A further object of the present invention is to provide a gas concentration meter that can be automatically calibrated based on the diagnosis result.

[0008]

Therefore, in the method for inspecting a gas concentration meter of the present invention, a state in which the concentration of a sample gas of known concentration is measured is artificially generated without using the sample gas. I chose That is, the light as if it had passed through the sample gas having a predetermined concentration was emitted from the light source. Then, the operation of the gas densitometer is inspected by comparing the concentration obtained based on the light with a concentration value that defines the light amount of the light. Further, the gas densitometer of the present invention is a gas densitometer capable of performing the above-described inspection method, and self-diagnosis and automatic calibration can be performed based on the comparison result.

Therefore, according to the gas concentration meter inspection method of the present invention, the concentration of the predetermined substance in the sample gas is determined by the amount of the predetermined light transmitted through the sample gas and the predetermined light of the reference gas not containing the substance. A method for inspecting a gas densitometer based on the amount of transmitted light, the sample having a known concentration by using light corresponding to transmitted light obtained by irradiating the gas containing the predetermined substance with a predetermined concentration with the predetermined light. A state in which the gas is irradiated with the predetermined light is generated in a pseudo manner, a concentration is obtained based on the amount of transmitted light obtained in the state, and the concentration is defined as the predetermined amount of light in which the pseudo state is generated. The operation and accuracy of the gas densitometer is checked by comparison with the concentration.

In the gas concentration meter of the present invention, the concentration of a predetermined substance in the sample gas is determined by a predetermined light transmission amount to the sample gas and a predetermined light transmission amount to a reference gas not containing the substance. A gas concentration meter that is obtained based on
A gas containing member capable of selectively filling the sample gas or the reference gas and transmitting light in at least one direction, a predetermined amount of first light at a predetermined wavelength, and a gas containing the predetermined substance at a predetermined concentration. A light source that generates a second light of a light amount corresponding to the transmitted light obtained by irradiating the first light and irradiates the gas containing member, and a light source that is irradiated from the light source and transmits the gas containing member. Means for detecting the amount of the emitted light, and performing predetermined signal processing based on two transmitted light amounts obtained by transmitting the first light through the reference gas and the sample gas to determine the concentration of the predetermined substance. Means for obtaining, and as the two transmitted light amounts, the transmitted light amount of each of the first light and the second light transmitted through a gas not containing the predetermined substance, and the signal based on each transmitted light amount. The concentration obtained by performing the treatment and before A means for comparing said predetermined concentration that defines the amount of light of the second light, and means for outputting the comparison result.

Specifically, the means for comparing performs the signal processing on the basis of the transmitted light amount of each of the first light and the second light which is transmitted through a gas containing no predetermined substance. The difference between the obtained density and the predetermined density that defines the light amount of the second light is calculated, and the difference is output by the output means. More specifically, the means for making the comparison obtains the first light and the second light by the signal processing means based on the amount of transmitted light of each light transmitted through the gas not containing the predetermined substance. The difference between the obtained density and the predetermined density that defines the light amount of the second light, determines whether the difference is within a predetermined accuracy, and outputs the result in the means for outputting. Output

Further, the gas concentration meter of the present invention determines the concentration of a predetermined substance in the sample gas based on the light transmission amount of the sample gas and the light transmission amount of the reference gas not containing the predetermined substance. A gas densitometer to be sought, which is capable of selectively filling the sample gas or the reference gas and transmitting light in at least one direction, and a first light amount having a predetermined light amount at a predetermined wavelength.
Light and a second amount of light corresponding to the transmitted light obtained by irradiating the gas containing the predetermined substance with the predetermined concentration with the first light, and irradiating the gas containing member with the light. A means for detecting the amount of light emitted from the light source and transmitted through the gas containing member, and two transmitted light amounts obtained by transmitting the first light through the reference gas and the sample gas, A means for performing a predetermined signal processing using a predetermined parameter to obtain the concentration of the predetermined substance, and the first light and the second light as the two transmitted light amounts.
Of the light having passed through the gas that does not contain the predetermined substance, and the concentration obtained by the signal processing based on the respective amount of the transmitted light is the predetermined amount that defines the light amount of the second light. And means for updating the parameters used in the signal processing so as to match the density within a predetermined accuracy.

Preferably, the light source emits different amounts of light for different concentrations as the second amount of light corresponding to the transmitted light obtained by irradiating the gas containing the certain substance with a certain concentration with the first light. Is capable of emitting a plurality of lights, the means for updating the parameter obtains the density for each light, and matches the obtained density with the density defining the light amount of the light within a predetermined accuracy. A plurality of conditions for performing the above are extracted, and a plurality of parameters used in the signal processing are updated based on the extracted conditions.

Specifically, the means for detecting the amount of light is
The photoelectric conversion device receives a light emitted from the light source and transmitted through the gas containing member, and has a photoelectric conversion element that converts the received light into an electric signal according to the amount of light, and the means for performing the signal processing is the photoelectric conversion. An amplifier circuit for amplifying an electric signal output from an element, an A / D conversion circuit for converting the amplified electric signal into a digital signal, and an arithmetic circuit for performing an operation using the A / D-converted digital signal Have.

Further, specifically, the light source is a light source capable of emitting ultraviolet rays of different amounts of light at predetermined wavelengths, and the gas concentration meter of the present invention determines the ozone concentration of the sample gas by transmitting the ultraviolet rays to the sample gas. It is an ozone gas densitometer which is obtained by comparing the amount of ultraviolet rays with respect to a reference gas containing no ozone.

[0016]

The gas concentration meter inspecting method of the present invention controls the amount of light emitted from the light source to artificially create a state in which the concentration is measured for a gas having a known concentration, and based on the result, the gas concentration meter is measured. Is being inspected. Therefore, the operation of each component other than the control of the light source is the same as the operation during the normal measurement, and the gas concentration meter can be comprehensively inspected by using each of these components as the inspected part. Further, the control of the light emission amount of the light source can be controlled with higher accuracy than in the case where the light amount is mechanically adjusted using an optical filter, for example. Therefore, the difference between the concentration measurement result for a gas with a known concentration generated by controlling the amount of light and the concentration defining the amount of light is
It can be used as the error of the gas concentration meter, in other words, as the accuracy.

Further, the gas densitometer of the present invention compares the concentration obtained by changing the light source with a light source capable of emitting an arbitrary amount of light in order to perform the inspection, and the specified value. And means. Therefore, the above-mentioned inspection can be performed, the measurement error can be automatically obtained, whether the error is within a predetermined range can be determined, and further, the error can be automatically corrected. Becomes

[0018]

EXAMPLE will be described with reference to FIG. 1 for ozone concentration meter as a first embodiment of a gas concentration meter of the first embodiment the present invention. FIG. 1 is a block diagram showing the configuration of the ozone concentration meter of the first embodiment. The ozone concentration meter 1 includes a reference gas supply unit 11, a sample gas supply unit 12, an electromagnetic valve 13, a cell 14, a pump 15, a power supply unit 16, a light source control unit 17, a light source 18, a sensor 19, an amplification unit 20, and A.
/ D conversion unit 21, calculation unit 22, parameter storage unit 23,
The display unit 24 and the comparison unit 25 are included. The respective units are controlled by a control unit (not shown), whereby the respective units cooperate with each other to perform a predetermined operation.

The operation of each unit will be described below. The reference gas supply unit 11 supplies a reference gas containing no ozone to the cell 14. The reference gas supply unit 11 is the electromagnetic valve 1
When 3 is switched and the reference gas can be filled into the cell 14 from the reference gas supply unit 11, the cell 14 is filled with the reference gas at a predetermined pressure.

The sample gas supply unit 12 supplies the sample gas whose ozone concentration is to be measured to the cell 14. When the electromagnetic valve 13 is switched and the sample gas can be filled into the cell 14 from the sample gas supply unit 12, the sample gas supply unit 12 fills the cell 14 with the sample gas at a predetermined pressure. The electromagnetic valve 13 is a solenoid valve for selecting the gas with which the cell 14 is filled, and is appropriately switched by a control unit (not shown).

The cell 14 is a container for containing gas for allowing the light emitted from the light source 18 to pass through the gas. The cell 14 has a gas inlet and a gas outlet (not shown). The gas pipe joined to the inlet is the electromagnetic valve 13 and the gas pipe joined to the outlet is the pump 1
Connected to 5. The gas supplied to the cell 14 is selected by the electromagnetic valve 13 from the reference gas supply unit 11 or the sample gas supply unit 12, and is filled into the cell 14 from the suction port. Further, the gas for which the amount of transmitted light has been measured is sucked by the pump 15 and discharged from the discharge port.

The size of the cell 14 is determined by the gas concentration to be measured by the gas concentration meter. That is, when a high-concentration ozone gas is to be measured, the cell 14
The length in the optical path direction of is set to a very small width. For example, the minimum width may be set to 1 mm or less.
Further, when a low-concentration ozone gas such as ozone concentration in the atmosphere is to be measured, the length should be long enough to increase the absolute absorption amount of light as much as possible. The wall of the cell 14 through which the light emitted from the light source 18 passes is a transparent wall such as glass, and the absorption of light by this wall is almost negligible.

The pump 15 is a pump for discharging the gas contained in the cell 14. The power supply unit 16 is a light source 1.
8 is a power supply circuit for supplying electric power to 8 and is an AC-DC converter circuit for converting AC input power into DC power. The light source control unit 17 is a control circuit that adjusts the light amount of the light source 18, and is a DC-DC converter that uses an inverter. The light source control unit 17 changes the switching frequency, outputs a desired voltage, and adjusts the light amount of the light source 18 in accordance with a control signal from a control unit (not shown).

The light source 18 is a light source that emits light of a predetermined wavelength, and is a mercury lamp. The wavelength of the light is 254 nm, which is close to the peak value of the absorption curve of ozone, and the intensity of the light is determined by the current input by the light source control unit 17. The sensor 19 is illuminated by the light source 18 and the cell 1
It is provided at a position where it can receive the light transmitted through the gas filled in 4, and detects the amount of the light. The sensor 19 is composed of a photoelectric tube, and the received optical signal is converted into an electrical signal according to the amount of light.

The amplification section 20 is an amplification circuit for amplifying the electric signal output from the sensor 19 at a predetermined amplification factor.
The A / D converter 21 is an A / D converter that converts the electric signal amplified by the amplifier 20 into a digital signal. A
The / D converter 21 converts this signal into a 21-bit digital signal.

The calculation unit 22 calculates the ozone concentration in the sample gas based on the amount of light transmitted through the reference gas and the sample gas. The calculation unit 22 first stores the data representing the amount of transmission of the light emitted to the reference gas in a storage unit (not shown) in the calculation unit 22. Next, when data representing the amount of light transmitted through the sample gas is input, the constant C stored in the parameter storage unit 23 is calculated according to the Lambert-Beer law. calculate.

[0027]

## EQU1 ## C = A · log ₁₀ (I _O / I _X ) ... (1) where C: ozone concentration [ppm] I _O : light transmission amount with respect to reference gas I _X : light transmission amount with respect to sample gas A: constant

The constant A in the equation 1 is a constant determined by the equation 2 based on the ozone absorption coefficient and the cell length of the cell 14.

[0029]

[Formula 2] A = 10 ⁶ / (α · t) (2) where α: ozone absorption coefficient [cm ⁻¹ ] t: cell length [cm]

The calculated ozone concentration C is output to the display section 24 and the comparison section 25. Parameter storage unit 23
Is a memory for storing parameters used for the calculation of Expression 1 performed by the calculation unit 22. The display unit 24 includes an ozone concentration output from the calculation unit 22, and a comparison unit 25.
It is a display unit for displaying the diagnostic result of the ozone concentration meter 10 output from the ozone concentration meter 10, and is composed of a 7-segment fluorescent display tube having a predetermined number of digits.

The comparison unit 25 outputs the ozone concentration C output from the calculation unit 22 when the ozone concentration meter 1 is in the self-diagnosis mode.
Is compared with the reference ozone concentration C ′, and the ozone concentration meter 1 obtains a self-diagnosis result. That is, the ozone concentration C output from the calculation unit 22 is compared with the ozone concentration C ′ stored in advance in the comparison unit 25, and if the difference is within a predetermined range, the ozone concentration meter 1 is determined to be normal. If the difference is greater than or equal to the predetermined range, the ozone concentration meter 1 determines that there is an abnormality and outputs a signal to that effect to the display unit 24. The self-diagnosis mode is to control the amount of light emitted from the light source 18 to a predetermined value to artificially measure the gas concentration without using a sample gas and compare the obtained concentration with a theoretical value. The operation of performing the self-diagnosis of the ozone concentration meter 1 will be described.

Next, a method for measuring the ozone concentration by the ozone concentration meter 1 having such a configuration will be described.
An operation of performing normal ozone concentration measurement is called an operation in the measurement mode. Reference gas supply unit 11 and sample gas supply unit 12
The reference gas and sample gas supplied from the electromagnetic valve 13
Cell 1 and the cells 1 are alternately switched at a predetermined timing.
4 is filled. First, when the reference gas is sucked into the cell 14, ultraviolet light of a predetermined intensity is emitted from the light source 18, passes through the reference gas in the cell 14, and is irradiated onto the sensor 19. The sensor 19 generates an electric signal according to the amount of light. The electric signal is amplified by the amplifier 20, quantized by the A / D converter 21, and input to the calculator 22. In the calculation unit 22, the input value is stored in a storage unit (not shown) in the calculation unit 22 as the light transmission amount I _{O with} respect to the reference gas.

Next, the electromagnetic valve 13 is switched, and the sample gas is sucked into the cell 14 from the sample gas supply unit 12. In that state, the light source 18 is again irradiated with ultraviolet rays,
By the same operation as in the case of the reference gas, the light transmission amount I _X with respect to the sample gas is obtained and stored in the calculation unit 22. Then, in the calculation unit 22, the calculation of Formula 1 is performed based on the stored light transmission amount I _O for the reference gas and the stored light transmission amount I _X for the sample gas, and the ozone concentration C
To calculate.

Next, the operation of the ozone concentration meter 1 in the self-diagnosis mode for self-diagnosis will be described. In the self-diagnosis mode, each part is controlled at the same timing as in the measurement mode described above, but the reference gas supply part 11, the sample gas supply part 12, the electromagnetic valve 13, and the pump 1 are controlled.
No. 5 does not actually operate, and neither the reference gas nor the sample gas is used. First, in the measurement mode described above, the reference gas is the cell 14
The ultraviolet light of a predetermined intensity is emitted from the light source 18 at the timing of being inhaled into the cell 14, passes through the cell 14, and is irradiated to the sensor 19. The sensor 19 generates an electric signal according to the amount of light. The electric signal is amplified by the amplification unit 20, quantized by the A / D conversion unit 21, and the calculation unit 22.
Is input to In the calculation unit 22, the input value corresponds to the first light transmission amount I corresponding to the light transmission amount with respect to the reference gas.
_It is stored as _{O in} a storage unit (not shown) in the calculation unit 22.

Next, the electromagnetic valve 13 is switched, and at the timing when the sample gas is sucked into the cell 14 during the operation in the above-mentioned measurement mode, the light source 18 emits an ultraviolet ray weaker than the predetermined intensity, and the inside of the cell 14 is emitted. Pass through, sensor 1
Irradiate 9. Therefore, the sensor 19 receives weakened ultraviolet rays as if they were absorbed by passing through ozone gas. Then, based on the received light, the second light transmission amount I _X corresponding to the light transmission amount with respect to the sample gas is obtained and stored in the calculation unit 22 in the same procedure as described above. Then, the calculation unit 22 calculates the equation 1 based on the first light transmission amount I _O corresponding to the light transmission amount with respect to the reference gas and the second light transmission amount I _X corresponding to the light transmission amount with respect to the sample gas. Then, the pseudo ozone concentration C ′ is calculated. Then, the comparison unit 25 compares the pseudo ozone concentration C ′ with a predetermined ozone concentration C ′, determines whether the difference is within a predetermined value, and makes a diagnosis.

Thus, the ozone concentration meter 1 of the first embodiment
In the above, the light amount emitted by the light source 18 is changed so that the light amount received by the sensor 19 receives a desired amount of light, and if each part is operating normally, a predetermined reference ozone concentration C ′ is obtained. I was allowed to. Therefore, by checking the value, it is possible to comprehensively determine whether or not each unit is operating normally.

Second Embodiment A second embodiment of the gas concentration meter of the present invention will be described with reference to FIG. 2 by exemplifying an ozone concentration meter as in the first embodiment.
The ozone densitometer of the second embodiment is an ozone densitometer adapted to automatically calibrate the error based on the result of the self-diagnosis shown as the first embodiment. FIG. 2 is a block diagram showing the configuration of the ozone concentration meter of the second embodiment. The ozone densitometer 2 has the same configuration as the ozone densitometer 1, but instead of the comparison unit 25 of the first embodiment, a calibration unit 26 that corrects the contents of the parameter storage unit 23 based on the output of the calculation unit 22.
Is different from the first embodiment.

The operation of the components different from those of the first embodiment will be described below. The light source control unit 17 controls the light source 18 so as to generate two kinds of light amounts of light as light equivalent to light that has transmitted the sample gas in a pseudo manner. That is, the light source 18 is controlled so that a state in which the concentration is measured for two types of ozone gas having different concentrations can be pseudo-realized. The sensor 19, the amplification unit 20, and the A / D conversion unit 21 perform signal processing as in the first embodiment. The calculation unit 22 obtains two kinds of ozone concentrations C1 and C2 corresponding to each concentration based on the equation 3 in consideration of the correction.

[0039]

[Equation 3] C = p · A · log ₁₀ (I _O / I _X ) + q (3) where C: ozone concentration [ppm] I _O : light transmission amount with respect to the reference gas I _X : with respect to the sample gas Light transmission amount A: Constant determined by Equation 2 p: Sensitivity correction coefficient q: Offset correction coefficient

The sensitivity correction coefficient q is a correction coefficient for a proportional error, and the offset correction coefficient q is a correction coefficient for an overall shift. The initial values of the counts p and q are 1
Is. The parameter storage unit 23 stores the constant A in Expression 3 and the correction coefficients p and q. The calibration unit 26 performs the change by changing the light emission amount of the light source 18.
Results of pseudo-concentration measurement for various kinds of ozone gas C1, C
Based on 2, the sensitivity correction coefficient p and the offset correction coefficient q such that each measurement result becomes equal to the theoretical value are calculated. The theoretical value is a predetermined concentration that regulates the amount of light emitted from the light source 18 in order to obtain the concentrations C1 and C2. Each of the correction values stored in the parameter storage unit 23 is updated with the calculated sensitivity correction coefficient p and offset correction coefficient q.

According to the ozone concentration meter 2 of the second embodiment having such a configuration, for example, an error such as a variation of the amplification factor in the amplification section 20 can be automatically taken into consideration to always obtain a correct concentration value. It is possible to realize an ozone densitometer that can be used, that is, an ozone densitometer that can be automatically calibrated.

The present invention is not limited to the first and second embodiments described above, and various modifications can be made. For example, regarding the method of determining the gas concentration, in the present embodiment, the reference gas and the sample gas were each irradiated with light once, and the gas concentration was determined based on the amount of transmitted light. A method may be used in which the final gas concentration is obtained by repeating the operation and obtaining the average thereof. Further, in the above-described embodiment, as a method of measuring the ozone concentration, first, the value I _O of the light transmission amount with respect to the reference gas is obtained, and then the value I _X of the light transmission amount with respect to the sample gas is obtained, and based on them, Equation 1 Was calculated to obtain the ozone concentration. However, in this case, the light transmission amount may be obtained first from the sample gas.

In the present embodiment, the wall of the cell 14 through which the light emitted from the light source 18 passes is a transparent wall such as glass, and the absorption of light by this wall is assumed to be negligible. . Therefore, if the light absorption by the wall becomes a value that cannot be ignored, correct results cannot be obtained. However, in such a case, in the self-diagnosis mode, the amount of light corresponding to the transmitted light with respect to the gas of the predetermined concentration emitted by the light source 18 is increased by increasing the amount of light absorbed by the wall of the cell 14 accurately. It can be operated.

Further, in this embodiment, after converting the photoelectrically converted electric signal into a digital signal, calculation is performed by a digital processor to obtain the density as a digital value. However, it may be configured by an analog circuit. For example, the computing unit for computing Formula 1 or Formula 3 may be configured by an analog computing circuit using a LOG amplifier or the like, and the amplified electrical signal may be computed by the computing circuit to obtain the concentration.

In addition, in the first embodiment, the display unit 24
The result of the comparison made by the comparison unit 25 indicates whether or not the ozone concentration meter 1 is normal. However, other information such as the value of the difference between the theoretical value and the calculated value may be displayed. Similarly, also in the second embodiment, information relating to the configuration of the correction value may be displayed on the display unit 24.

Further, the power source portion of this embodiment is constituted by a power source portion for converting from AC power source to DC power source and a light source control portion for DC-DC conversion, whereby the light amount of the light source is adjusted. However, it may be a gas concentration meter used in a DC power source, and in that case, the AC-DC converter is naturally unnecessary. Also, how to adjust the light emission amount of the light source,
It may be performed by any method. In addition, the amplification unit 20, A /
The circuit configurations of the amplification circuit and the A / D conversion circuit in the D conversion unit 21 may also be configured by known and suitable circuits.

Further, although the ozone concentration meter has been described as an example in the present embodiment, the gas concentration meter of the present invention is not limited to the ozone concentration meter. Any densitometer can be applied as long as it is a densitometer that irradiates a predetermined gas with a light beam and measures the gas concentration based on the amount of the light transmitted.

[0048]

According to the inspection method of the gas concentration meter of the present invention, the emission amount of the light source that can be controlled with high accuracy is controlled, and the state in which the concentration is measured for the gas whose concentration is known is simulated. We are making and inspecting the gas concentration meter. Therefore,
The operation and accuracy of the gas concentration meter could be tested without actually using the gas containing the substance to be measured.

Further, according to the gas concentration meter of the present invention, the operation of each component during inspection is the same as the operation during normal measurement, so that a comprehensive inspection is performed using each of these components as the inspected part. be able to. Further, the difference between the density obtained by changing the light source and the density defining the light source can be used as an error of the densitometer, in other words, as accuracy. Therefore,
It is possible to automatically obtain the measurement error, determine whether the error is within a predetermined range, and also to automatically correct the error, enabling self-diagnosis or automatic calibration. A gas concentration meter can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an ozone concentration meter according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an ozone concentration meter according to a second embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Ozone concentration meter 11 ... Reference gas supply unit 12 ... Sample gas supply unit 13 ... Electromagnetic valve 14 ... Cell 15 ... Pump 16 ... Power supply unit 17 ... Light source control unit 18 ... Light source 19 ... Sensor 20 ... Amplification unit 21 ... A / D conversion unit 22 ... Calculation unit 23 ... Parameter storage unit 24 ... Display unit 25 ... Comparison unit 26 ... Calibration unit

Claims (8)

[Claims] 1. A gas concentration for determining the concentration of a predetermined substance in a sample gas based on a predetermined light transmission amount for the sample gas and a predetermined light transmission amount for a reference gas not containing the predetermined substance. In the meter, using the light corresponding to the transmitted light obtained by irradiating the gas containing the predetermined substance with the predetermined concentration with the predetermined light, the predetermined gas is irradiated with the predetermined light with respect to the sample gas of which the concentration of the predetermined substance is known. A state is generated in a pseudo manner, the concentration is obtained based on the amount of transmitted light obtained in the state, the concentration is compared with the predetermined concentration that defines the light amount of the light that generates the pseudo state, and the gas concentration meter Inspection method of gas densitometer to inspect the operation and accuracy of. 2. A gas concentration for determining a concentration of a predetermined substance in a sample gas based on a predetermined light transmission amount with respect to the sample gas and a predetermined light transmission amount with respect to a reference gas not containing the predetermined substance. A gas accommodating member capable of selectively filling the sample gas or the reference gas and transmitting light in at least one direction; a first light of a predetermined light amount at a predetermined wavelength; and the predetermined substance. A light source that generates a second light of a light amount corresponding to transmitted light obtained by irradiating the gas having a predetermined concentration with the first light, and irradiates the gas containing member with the light, A light amount detecting means for detecting a light amount of light transmitted through the gas containing member, and performing predetermined signal processing based on two transmitted light amounts obtained by transmitting the first light through the reference gas and the sample gas. , Find the concentration of the specified substance And a signal processing unit that uses, as the two transmitted light amounts, the transmitted light amounts of the first light and the second light, which are transmitted through a gas that does not contain the predetermined substance, based on the transmitted light amounts. A gas densitometer, comprising: a comparing unit that compares the concentration obtained by the signal processing unit with the predetermined concentration that defines the light amount of the second light; and an output unit that outputs the comparison result of the comparing unit. 3. The comparing means includes the first light and the second light.
Difference between the concentration obtained by the signal processing means based on the transmitted light amount of each light transmitted through the gas containing no predetermined substance and the predetermined concentration defining the light amount of the second light. The gas concentration meter according to claim 2, wherein the gas concentration is calculated and the output means outputs the difference calculated by the comparison means. 4. The comparing means includes a first light and a second light.
Difference between the concentration obtained by the signal processing means based on the transmitted light amount of each light transmitted through the gas containing no predetermined substance and the predetermined concentration defining the light amount of the second light. The gas concentration meter according to claim 2, wherein the gas concentration meter calculates and determines whether or not the difference is within a predetermined accuracy, and the output unit outputs the determination result determined by the comparison unit. 5. A gas concentration for determining a concentration of a predetermined substance in a sample gas based on a predetermined light transmission amount with respect to the sample gas and a predetermined light transmission amount with respect to a reference gas not containing the predetermined substance. A gas accommodating member capable of selectively filling the sample gas or the reference gas and transmitting light in at least one direction; a first light of a predetermined light amount at a predetermined wavelength; and the predetermined substance. A light source that generates a second light of a light amount corresponding to transmitted light obtained by irradiating the gas having a predetermined concentration with the first light, and irradiates the gas containing member with the light, A light amount detecting means for detecting a light amount of light transmitted through the gas containing member, and a predetermined parameter based on two transmitted light amounts obtained by transmitting the first light through the reference gas and the sample gas. Predetermined signal processing using Signal processing means for determining the concentration of the predetermined substance, and the transmitted light amount of each light obtained by transmitting the first light and the second light as the two transmitted light amounts through the gas not containing the predetermined substance. So that the density obtained by the signal processing means on the basis of each transmitted light quantity matches the predetermined density that defines the light quantity of the second light within a predetermined accuracy.
A gas densitometer having a calibration means for updating the parameters used in the signal processing means. 6. A plurality of light sources having different light amounts for different concentrations are used as the second light having a light amount corresponding to transmitted light obtained by irradiating the gas containing the predetermined substance with a predetermined concentration with the first light. Is capable of emitting light, and the calibration means obtains the density for each of the lights, and a plurality of means for matching the obtained density with the density defining the light amount of the light within a predetermined accuracy. The gas concentration meter according to claim 5, wherein the condition is extracted, and a plurality of parameters used in the signal processing means are updated based on the extracted condition. 7. The light amount detecting means has a photoelectric conversion element for receiving the light emitted from the light source and transmitted through the gas containing member, and converting the received light into an electric signal corresponding to the light amount. The signal processing means includes an amplification circuit for amplifying the electric signal output from the photoelectric conversion means, an A / D conversion circuit for converting the amplified electric signal into a digital signal, and the A / D conversion circuit.
The gas concentration meter according to any one of claims 2 to 6, further comprising an arithmetic circuit that performs an arithmetic operation using a digital signal that has been D / D converted. 8. The light source is capable of emitting different amounts of ultraviolet rays of a predetermined wavelength, and the ozone concentration in the sample gas is determined by the amount of ultraviolet rays transmitted to the sample gas and the amount of ultraviolet rays transmitted to a reference gas not containing ozone. The gas concentration meter according to any one of claims 2 to 7, which is obtained by comparing with.