JPH0921773A - Organoleptic amount measuring electric circuit by semiconductor gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to measure offensive odor by human smell value 'odor concentration' or 'odor index' by outputting the output of a semiconduc tor gas sensor by an electric circuit having a variable resistor and an amplifier. SOLUTION: The output of a semiconductor gas sensor 1 is output by an electric circuit having a variable resistor 2 and an amplifier 3a. Thus, an output measuring equation becomes VRL=Vcx VL/Rs (where VRL: the measured value of the sensor, Vcx , Rs : the measuring circuit voltage and resistance value Ωin odor subtance concentration x of the sensor). When it is plotted on logarithmic graph, it becomes a straight line. That is, Stevin's law can be reproduced by the circuit, and the odor concentration can be measured and the odor index for a logarithmic value display can be measured.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to instrumental measurement of sensory amount of pollution malodorous gas.

[Prior Art] [0002] Hitherto, the sensory quantity has been measured by the human sense of smell.

[Problems to be Solved by the Invention] Currently, semiconductor gas sensors or synthetic bilayer membrane sensors are commercially available as odor sensors. However, the "odor index" which is the human sensory quantity or the three-point odor bag method is used. No measuring instrument capable of measuring the measured "odor concentration" has been realized. In the past, a measuring instrument for measuring the "odor intensity", which is a human olfaction value, using a semiconductor gas sensor has been commercially available, but a correct measurement value cannot be obtained and it is not popular. That is, the odor intensity is a value obtained by the Weber-Fechner equation 1 while the measurement value of the semiconductor gas sensor is obtained by equation 2. Therefore, the odor intensity is measured by the semiconductor gas sensor. Is not theoretically measured directly. In other words, it is no exaggeration to say that measuring instruments that ignore olfactory theory have been commercially available.

[0004]

[Equation 1]

[0005]

[Equation 2]

Conventionally, "6 levels of odor intensity" has been adopted as the unit for measuring bad odor in the bad odor prevention law in Japan, but currently available sensors are Weber, Fechner (Web
The sensor capable of directly expressing the er-Fechner formula has not been put to practical use. However, in April 1995, the Odor Control Law was revised, and the unit of measurement was revised to the "odor index" based on the human sense of smell. The "odor index" is a value obtained by multiplying the logarithmic value of the "odor concentration" measured by the three-point odor bag method (dilution method) by 10 times, that is, the value obtained by Equation 3, and the basis of the measurement is the "odor concentration". It is to ask. Therefore,
If there is a sensor that can display the "odor concentration" and a measuring circuit for it can be developed, it will be possible to measure the device regardless of the human sense of smell. In particular, the human sense of smell is not only affected by the weather, body condition, etc., but it is virtually impossible for a human to carry out long-term continuous monitoring. Therefore, instrumental measurement of human sensory quantity is desired.

[0007]

(Equation 3)

[Means for Solving Problems] Due to the revision of the law, the current unit of measurement is the “odor index”, and as described above, the “odor index” is calculated from the “odor concentration” by its definition. It is a thing. Therefore, if a sensor and an electric circuit capable of measuring the "odor concentration" can be realized, the "odor index" can be naturally measured. In particular, when considering that the "odor concentration" is obtained by the dilution method, a sensor applying the adsorption theory can theoretically be measured by the sensor. That is, Weber-Fechner's law of Leipzig University, which was found in the 1800s as a measurement formula for human senses, entered the 1900s in the Stevens of Harvard University.
It is further developed by s), and Stevens's law expressed by the equation 4 is known. However, since the past odor display unit was generally "odor intensity", when "odor intensity" was taken as the scale of the horizontal axis and "logarithmic value of concentration ratio" was taken as the scale of the vertical axis, "Odor intensity" between 1 and 3 is not linear in the measured value by Stevens' equation,
Since the measured values by the Weber and Fechner formulas have high linearity, the Stevens formula has not been evaluated in the olfactory field as being extremely unreliable. However, this is due to the fact that the "odor intensity" was adopted as the scale of the horizontal axis, which is a clear result from the mathematical formulas of Formulas 1 and 4. When the new legal regulation value "odor index" is adopted on the horizontal axis, since the "odor index" is a logarithmic value, the measured values by the Weber and Fechner formulas have no linearity, as is clear from the equation 1. On the contrary, it can be understood from the equation 4 that the measured value by the Stevens equation shows linearity. As a result of our six years of research, Stevens' law is "odor index" and "odor concentration" in the olfactory field.
It was found that the result agrees well with the measurement result of Eq.
Since it is a general formula equivalent to the number of adsorption formulas of Eurich), it can be judged that the “odor concentration” and “odor index” can be measured by a sensor based on the adsorption theory. Equations 4 and 5 are characterized in that they are straight lines when plotted on a logarithmic graph, and the human sensory quantity represented by the "odor index" and "odor concentration" is an index with respect to the index of the olfactory stimulus amount. It can be said to react.

[0009]

(Equation 4)

[0010]

(Equation 5)

However, the circuit shown in FIG. 2 is given by the manufacturer as the measurement circuit design of the conventional semiconductor gas sensor, and the measured value is obtained by the equation (6). When the logarithm of both sides is taken, the variable resistance value R is _added to the variable sensor resistance value _RS.
Since it is the logarithm of the sum with _L added, it is clearly not a straight line when plotted on a bilogarithmic graph, and it is necessary to measure the "odor concentration" and "odor index" of human olfactory values in the conventional electric circuit diagram 2. I can't.

[0012]

(Equation 6)

By outputting the output of the semiconductor gas sensor by the electric circuit composed of the amplifier 3a and the variable resistor 2 shown in FIG. 1, the output measurement formula becomes Equation 7. As is clear from the equation, it becomes a straight line when plotted on a log-log graph. That is, the electric circuit according to the present invention makes it possible to reproduce the Stevens' law, and it becomes possible to measure the "odor concentration" and the "odor index" by the logarithmic value display. The logarithmic value can be obtained by inserting a log amplifier after the electric circuit of FIG. 1, and can be easily obtained by a log calculation program like the measuring instrument.

[0014]

(Equation 7)

The role of the variable resistor 2 in the electric circuit of the present invention is, for example, when three kinds of sensors having different sensitivities are used, as shown in FIG. 3, for a gas having the same "odor index" value in logarithmic display. Three different measurement lines are obtained. By adjusting the initial value of the sensor for odorless air to a constant value which is the same for all three types of sensors, the measurement straight line by logarithmic value display is unified into one straight line as shown in FIG. Further, changing the value R _L of the variable resistor 2 means that when plotted on a logarithmic log graph (“odor index” display), the dotted line in FIG. 5 is moved up and down in parallel. When set to, it is possible to display the "odor index", which is the human olfactory value, as the device measurement value. The initial value of 1 for odorless air is defined by the definition that the "odor concentration" of odorless air is 1, not 0.

[Embodiment] An embodiment in which the present invention is measured by using a measuring instrument having the electric circuit shown in FIG. 1 is shown in FIGS.
Shown in As the measurement system, in order to eliminate the influence of humidity, the measurement system shown in FIG. 7 incorporating an automatic temperature and humidity controller was used.

FIG. 5 shows an initial value of 150 for odorless air.
Adjust to mV (millivolt) and set a value of 150 mV as a starting point 1
Is a graph when the logarithmic value of the measured value is obtained by the built-in software program and 2.5 is added to each measured value, all are automatically calculated by the software program,
Is displayed. The target gas is a high-concentration malodorous gas sampled from an actual urban wastewater treatment plant or human waste treatment plant, and it is shown that it matches the "odor index" by the human sense of smell with a correlation coefficient of 0.96 or more. . It should be noted that the sludge gas of the sewage treatment plant and the malodorous gas collected from the aeration tank of the human waste treatment plant contain a large amount of NOx which is an oxidizing gas as a result of biological reaction, and therefore cannot be measured by the semiconductor gas sensor. There was a kind of malodorous gas.

FIG. 6 shows a measurement of low-concentration odor at the boundary line of the same sewage treatment plant and human waste treatment plant.
The initial value for odorless air is 500m with variable resistance 2.
This is a plot of logarithmic values of values measured by adjusting the value to V and using the value as a starting point 1. It indicates that the measured value is directly obtained as the "odor index" in the relationship of 1: 1.

[Operation] The circuit shown in FIG. 1 makes it possible to obtain a curve which is a basis of olfactory theory.

[Effect] It has become possible to measure the sensory amount of equipment, which is conventionally measured by the human sense of smell.

[0021]

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of the present invention.

FIG. 2 is a designated circuit diagram of a semiconductor gas sensor manufacturer.

FIG. 3 is a measurement straight line diagram when three types of sensors having different sensitivities are used. The horizontal axis shows the human olfactory measurement value (odor index), and the vertical axis shows the device measurement value (odor index).

FIG. 4 is a measurement line obtained by making the initial values equal to each other by adjusting the variable resistance 2 for three types of sensors.
The horizontal axis shows the human olfactory measurement value (odor index), and the vertical axis shows the device measurement value (odor index).

FIG. 5 shows a relationship between measurement of a device having an electric circuit according to the present invention and human olfactory value (measurement of high concentration malodorous gas). Adjust to an initial value of 150 mV for odorless air. Graph when 2.5 was added to each device measurement value (logarithmic value). The horizontal axis shows the human olfactory measurement value (odor index), and the vertical axis shows the device measurement value (odor index).

FIG. 6 shows a relationship between a device having an electric circuit according to the present invention and a human olfactory value (measurement of a site boundary line low-concentration malodorous gas). Adjust to an initial value of 500 mV for odorless air.
By adjusting the variable resistance 2, the human olfactory value and the device measurement value have a 1: 1 relationship. The horizontal axis shows the human olfactory measurement value (odor index), and the vertical axis shows the device measurement value (odor index).

FIG. 7 shows a measurement flow sheet for measuring the device.

[Explanation of symbols]

1 ... Semiconductor gas sensor 2 ... Variable resistance (resistance value R _L ) 2a ... Variable resistance for minute adjustment 2b ... Variable resistance for large adjustment and adjustment 3a ... Amplifier 3b ... Amplifier 4 ... Resistance 5 ... Resistance 6 ... Connector 7 ... Transformer 8 ... Measurement circuit voltage V _C 9 ... Measurement voltage of semiconductor sensor _VRL 10 ・ ・ ・ ・ Temperature and humidity automatic adjuster 11 ・ ・ ・ ・ Gas measurement piping line 12 ・ ・ ・ ・ Air measurement piping line 13 ・ ・ ・ ・ ・ ・ Activated carbon cylinder 14 ・ ・ ・ ・ ・ ・ Bubbling tank 15 ・ ・ ・ ・ ・ ・ Cooling Panel 16 ... Heating panel 17, 18, Drainbin 19 ... Measuring device 20, 21, Solenoid valve 22 ... Sensor housing (sensor 1 installation) 23 ... Measuring pump 24 ...・ Needle valve 25 ・... flow meter

Claims (3)

[Claims] 1. An amplifier 3 for outputting the output of the semiconductor gas sensor 1.
a, a functional amount by a semiconductor gas sensor characterized by measuring "human odor""odorconcentration"("odorconcentration" required by the three-point odor bag method in the dilution method) by an electric circuit composed of a variable resistor 2 Measuring electrical circuit. 2. The "odor index", which is a human olfactory value, obtained by multiplying the logarithmic value of "odor concentration" obtained in claim 1 by 10.
The electric circuit for measuring the functional quantity by the semiconductor gas sensor according to claim 1, wherein 3. The electric circuit according to claim 1, wherein the variable resistor 2 is adjusted to adjust the initial value of the sensor for odorless air to a constant value which is always the same, and then the initial value for odorless air is measured as 1. 2. A functional amount measuring electric circuit using the semiconductor gas sensor according to claim 1.