JPH09229841A - Smell measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure smell with a simple constitution using a general-purpose temp. sensor and a humidity sensor by outputting a warning signal when the generation of a drift is expected by fluctuations of temp. and humidity. SOLUTION: A measuring cell 9 is reduced in pressure by a pump 8 to suck zero point corrected air and this air is measured by a smell sensor 1, a temp. sensor 2 ad a humidity sensor 3 to calibrate a zero point. At the same time, a zero point calibration signal 103 is inputted to a counter circuit 13 and sample hold circuits 10a, 10b. The circuit 13 sets the count value at that time to zero and the circuits 10a, 10b hold temp. and humidity at that time. Air 100 to be measured is sucked to measure the smell, temp. and humidity of the air 100 by the respective sensors. A comparator 11a(11b) compares the output of the sensor 2(3) with the output of the circuit 10a(10b) and, when the comparison result exceeds a definite value, the outputs are set to a high level and a logical circuit 12 outputs a warning signal 104. Therefore, it is unnecessary to actually correct temp. and humidity and temp. and humidity drift simulators are dispensed with and the constitution becomes simple.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an odor measuring device for measuring an odor substance in a gas, and more particularly to an odor measuring device having a simple structure.

[0002]

2. Description of the Related Art A conventional odor measuring device detects the odor concentration by detecting a change in resonance frequency of an odor sensor using an AT-cut crystal oscillator or a surface acoustic wave device. However, since the odor sensor is easily affected by temperature and humidity, temperature compensation and humidity compensation were necessary.

FIG. 2 is a block diagram showing an example of such a conventional odor measuring device. In FIG. 2, 1 is an odor sensor using a crystal oscillator or the like, 2 is a humidity sensor, 3 is a temperature sensor, 4 is a humidity drift simulator, 5 is a temperature drift simulator, 6 and 7 are subtractors, 8 is a pump,
Reference numeral 9 is a measuring cell, 100 is a gas to be measured, 101 is an exhaust gas, and 102 is an output signal. Further, the pump 8 and the measuring cell 9 constitute a gas introducing means 50.

The odor sensor 1, the humidity sensor 2 and the temperature sensor 3 are arranged in the measuring cell 9, and a pump 8 is installed immediately before the exhaust port of the measuring cell 9.

The output of the odor sensor 1 is connected to the addition input terminal of the subtractor 6, the output of the humidity sensor 2 is connected to the humidity drift simulator 4, and the output of the temperature sensor 3 is connected to the temperature drift simulator 5.

The output of the humidity drift simulator 4 is connected to the subtraction input terminal of the subtractor 6, the output of the subtractor 6 is connected to the addition input terminal of the subtractor 7, and the output of the temperature drift simulator 5 is the subtraction of the subtractor 7. Connected to the input terminal.
The output of the subtractor 7 is output as the output signal 102.

The operation of the conventional example shown in FIG. 2 will be described. First, the pump 8 removes the gas in the measurement cell 9 from the exhaust gas 1
By exhausting outside the measuring cell 9 as 01, the inside of the measuring cell 9 becomes negative pressure. Therefore, the gas to be measured 100 is sucked into the measurement cell 9.

The odor sensor 1, the humidity sensor 2 and the temperature sensor 3 respectively measure the odor, humidity and temperature of the gas 100 to be measured.

The humidity drift simulator 4 calculates and outputs an output fluctuation component of the odor sensor 1 when the humidity changes when the odor component is "0" based on the output change of the humidity sensor 2.

Similarly, the temperature drift simulator 5 calculates and outputs the output fluctuation component of the odor sensor 1 when the temperature changes when the odor component is "0", based on the output change of the temperature sensor 3.

Finally, the output signals of the odor sensor 1 are subtracted by the subtracters 6 and 7 from the outputs of the humidity drift simulator 4 and the temperature drift simulator 5.

As a result, it is possible to perform temperature compensation and humidity compensation by subtracting the fluctuation component of the odor sensor 1 due to changes in humidity and temperature.

[0013]

However, the humidity drift simulator 4 and the temperature drift simulator 5 must accurately simulate the output fluctuation of the odor sensor 1 due to changes in humidity and temperature. Is difficult to approximate, and its characteristic itself is odor sensor 1
It will fluctuate due to variations and changes over time.

Therefore, the humidity drift simulator 4 and the temperature drift simulator 5 have a complicated structure, and there is a problem that the calibration work is required frequently. There is also a problem that a highly accurate humidity sensor and temperature sensor are required for accurate simulation of output fluctuation. Therefore, the problem to be solved by the present invention is to realize an odor measuring device capable of measuring an odor with a simple configuration using a general-purpose humidity and temperature sensor.

[0015]

In order to achieve such a problem, the present invention provides an odor measuring device for detecting an odor substance based on a change in resonance frequency due to adsorption of an odor substance on an odor sensor. Gas introducing means for introducing a measurement gas, the odor sensor installed in the gas introducing means, a humidity sensor installed in the gas introducing means for measuring the humidity of the gas to be measured, and in the gas introducing means Installed in the temperature sensor for measuring the temperature of the gas to be measured, a counter circuit for detecting a change in the resonance frequency based on the output of the odor sensor, each of the humidity sensor and the zero point calibration of the temperature sensor An alarm output means for outputting an alarm signal based on the output is provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of an odor measuring device according to the present invention.

Here, the numbers 1 to 3, 8, 9, 50, 100 and 101 are the same as those in FIG.

In FIG. 1, 10a and 10b are sample and hold circuits, 11a and 11b are comparators, 12 is a logical sum circuit (hereinafter referred to as an OR circuit), 13 is a counter circuit, 102a is an output signal, and 103 is a zero point. Calibration signal, 1
Reference numeral 04 is an alarm signal.

Further, 10a, 10b, 11a, 11b and 12 constitute alarm output means 51.

The odor sensor 1, the humidity sensor 2 and the temperature sensor 3 are arranged in the measuring cell 9, and a pump 8 is installed immediately before the exhaust port of the measuring cell 9.

The output of the odor sensor 1 is connected to the counter circuit 13, the output of the humidity sensor 2 is connected to one of the input terminals of the sample hold circuit 10a and the comparator 11a, and the output of the temperature sensor 3 is connected to the sample hold circuit 1.
0b and one input terminal of the comparator 11b, respectively.

The outputs of the sample hold circuits 10a and 10b are connected to the other input terminals of the comparators 11a and 11b, respectively, and the outputs of the comparators 11a and 11b are connected to the input terminal of the OR circuit 12, respectively.

The output of the counter circuit 13 is the output signal 102.
a, and the output of the OR circuit 12 is the alarm signal 10
4 is output. The zero point calibration signal 103 is input to the control terminals of the counter circuit 13 and the sample and hold circuits 10a and 10b, respectively.

The operation of the embodiment shown in FIG. 1 will be described here. Similarly to the conventional example, the pump 8 exhausts the gas in the measurement cell 9 as the exhaust gas 101 to the outside of the measurement cell 9 to negatively pressure the inside of the measurement cell 9.

First, as zero point calibration, instead of the measurement gas 100, a zero point calibration gas which is a gas containing no odor component is sucked, and the odor sensor 1, the humidity sensor 2 and the temperature sensor 3 are calibrated to zero point. Measure gas odor, humidity and temperature respectively.

At the same time, the zero point calibration signal 103 is input to the control terminals of the counter circuit 13 and the sample and hold circuits 10a and 10b, and the counter circuit 13 is set so as to output the count value at that time as "0", and the sample is sampled. The hold circuits 10a and 10b hold the humidity and temperature at that time.

On the other hand, in the normal measurement, the measurement gas 100 is sucked, and the odor sensor 1, the humidity sensor 2 and the temperature sensor 3 measure the odor, humidity and temperature of the measurement gas 100, respectively.

The comparator 11a compares the output of the humidity sensor 2 with the output of the sample hold circuit 10a, and when the output exceeds a certain value, the output is set to a high level. Further, the comparator 11
b is also the output of the temperature sensor 3 and the sample hold circuit 10b.
If it exceeds a certain value by comparing with the output of, the output is set to high level.

Since the outputs of the comparators 11a and 11b are connected to the OR circuit 12, the alarm signal 104 is output when the humidity or the temperature exceeds the predetermined value.

For example, the constant values of the humidity and the temperature are expressed as "±
5% RH "and" ± 5 ° C ", the humidity or temperature is" ± "compared to the humidity or temperature at the time of zero point calibration.
When there is a change of "5% RH" or "± 5 ° C" or more, the alarm signal 104 is output.

Here, in a normal use state of the portable type odor measuring device to which the present invention is applied, there is no significant temperature change or humidity change, and temperature correction and humidity correction are essentially unnecessary.

Therefore, in the present invention, the humidity correction and the temperature correction are not performed using the humidity drift simulator and the temperature drift simulator.

As a result, when the drift is expected to occur due to the temperature fluctuation and the humidity fluctuation, the warning signal 104 is output and the temperature correction and the humidity correction are not actually performed, so that the output fluctuation can be accurately simulated. Therefore, it is possible to use a general-purpose humidity and temperature sensor instead of the required highly accurate humidity sensor and temperature sensor.

Further, since the temperature correction and the humidity correction are not actually performed, the humidity drift simulator and the temperature drift simulator are not required, so that the structure is simplified.

Any method such as a buzzer, a lamp, or a display on the screen may be used to notify the operator of the alarm signal 104.

Although the zero point calibration signal 103 is used as the timing of sample and hold of humidity and temperature which are the reference of the alarm, it is not always necessary to use the same signal.

[0036]

As is apparent from the above description,
The present invention has the following effects. When a drift is expected to occur due to temperature fluctuations and humidity fluctuations, an alarm signal is output and temperature correction and humidity correction are not actually performed. An odor measuring device capable of measuring can be realized.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of an odor measuring device according to the present invention.

FIG. 2 is a configuration block diagram showing an example of a conventional odor measuring device.

[Explanation of Codes] 1 Odor sensor 2 Humidity sensor 3 Temperature sensor 4 Humidity drift simulator 5 Temperature drift simulator 6,7 Subtractor 9 Measuring cell 8 Pumps 10a, 10b Sample and hold circuit 11a, 11b Comparator 12 Logical sum circuit 13 Counter circuit 50 Gas Introducing Means 51 Alarm Output Means 100 Measured Gas 101 Exhaust Gas 102, 102a Output Signal 103 Zero Point Calibration Signal 104 Alarm Signal

Claims (1)

[Claims] 1. An odor measuring device for detecting an odor substance based on a change in resonance frequency due to adsorption of an odor substance to an odor sensor, wherein the gas introducing means introduces a gas to be measured, and the gas introducing means is installed in the gas introducing means. The odor sensor, a humidity sensor installed in the gas introducing unit for measuring the humidity of the measured gas, a temperature sensor installed in the gas introducing unit for measuring the temperature of the measured gas, and the odor A counter circuit that detects a change in the resonance frequency based on the output of the sensor, and an alarm output unit that outputs an alarm signal based on the outputs of the humidity sensor and the temperature sensor during zero-point calibration are provided. Odor measuring device.